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2024 | Buch

Structural Analysis of Historical Constructions

SAHC 2023 - Volume 1


Über dieses Buch

This book gathers the peer-reviewed papers presented at the 13th International Conference on Structural Analysis of Historical Constructions (SAHC), held in Kyoto, Japan, on September 12-15, 2023. It highlights the latest advances and innovations in the field of conservation and restoration of historical and heritage structures. The conference topics encompass history of construction and building technology, theory and practice of conservation, inspection methods, non-destructive techniques and laboratory testing, numerical modeling and structural analysis, management of heritage structures and conservation strategies, structural health monitoring, repair and strengthening strategies and techniques, vernacular constructions, seismic analysis and retrofit, vulnerability and risk analysis, resilience of historic areas to climate change and hazard events, durability, and sustainability. As such the book represents an invaluable, up-to-the-minute tool, providing an essential overview of conservation of historical constructions, and offers an important platform to engineers, architects, archeologists, and geophysicists.

Chapter Guidelines for Seismic Retrofitting of Earthen Historic Buildings in Peru and Latin America is available open access under a Creative Commons Attribution 4.0 International License via



History of Construction and Building Technology

Interpretation of Construction Procedures and Material Characteristics for the Fifth Century Gaya Tomb (Durak-ri No. 36 in Namwon), Korea

This study investigated the mineralogical and geochemical characteristics regarding the soil layer of the burial mound constituting the Durak-ri No. 36 tomb though various material analysis, and archaeometric discussed their homogeneity and construction techniques. A material analysis of the soil of the southwestern and southern soil layers of the tomb revealed that the layered soil was embanked by acquiring the soil from nearby sources, which had the same origin and a similar weathering process. Despite lack of meticulous selection process for the soil utilized in constructing the burial mound, there were selection and mixture in some soil layers. The construction process of the target ancient tomb must have involved three civil engineering stages in the order of flattening the boundary of a grave, installing the principal agent facilities of the burial and alternately embanking the burial mound with arrangement of the boundary. In this respect, the sources of stone production and the development of soil layers, both necessary for the construction of the ancient tombs, are considered to have been sufficient in the Durak-ri area. Moreover, the group presence of engineers can be inferred, who could design stone chambers and burial mounds using these resources, simultaneously implemented civil engineering technology, and engaged in mutual exchange and propagation.

Hyeri Yang, Chan Hee Lee
Teaching of Constructive Engineering at the Gründerzeit in Vienna

The Habsburg monarchy Gründerzeit starts after the bourgeois revolution in 1848 and lasts to the end of the First World War. It restructured the country from an agricultural to a technological state, which has a significant impact on construction in the rapidly growing modern metropolis Vienna. Two types of residential building, the noble tenement house along Ringstrasse and a rental house type for the masses characterize the construction technology in specific. Vienna nowadays still holds the biggest ensemble of Gründerzeit tenement houses worldwide. - Their construction of the early days, which appears to be conservative at first glance, turns out to be extremely progressive in retrospect, in terms of safety and sustainability. Building and chimney care regulations guaranteed exceptional fire safety very early on. Staircases had to be obligatory in stone. The well-considered use of masonry made of burned bricks with plaster or stone facades in historicist style, high-quality wooden casement windows and wooden double doors, and a mix of vault and wooden floor construction characterize the engineering of the founder period residential house. - The Vienna World Exhibition in 1873 already made the building types, construction methods and building technology of the modern metropolis its exhibition object. The building construction portfolio of Riewel and Schmid contained for the first time the consolidated building construction knowledge of 1873. Until 1900, it underwent several modifications and extensions of knowledge, to serve as solid and up-to-date teaching material for the middle level education of master artisans, as well as for the high-quality training of architects and structural engineers at technical colleges and universities. The paper will present materials and the usual construction methods of the Gründerzeit residential building in Vienna. The final building construction portfolio from 1897, which survived at TU Wien, serves as knowledge base for the paper, which will also give some inside into the development of those series of template works.

Caroline Jaeger-Klein
Quality of the Traditional Timber Houses in Croatia Proven in the M6.2 2020-Year Petrinja Earthquake

Traditional timber houses are still preserved in almost all villages in Pokuplje, a region in the continental part of Croatia. Due to the high-quality oak wood, abundant in nearby forests, and due to the method of construction, with horizontal timber elements (logs or, in later period, planks), connected well with carpentry joints, traditional timber houses have very good durability. Some houses withstood weathering and earthquakes for more than 400 years of their existence. These old structures proved their seismic resistance also in the damaging to heavily damaging 2020-year Petrinja earthquake (Richter scale Magnitude 6.2). This earthquake caused serious damage to many improperly built buildings, on bridges, roads and some of levees around Petrinja. The old timber houses, on the other hand, suffered only from some minor plaster cracks. The seismic resistance of traditional timber buildings is due to the high-quality oak wood and to the proper structural design with carpentry joints that allow micro-displacement. The timber walls, made of horizontal timber elements, connected with carpentry joints, were constructed on a base frame, made of strong timber beams. These frames were placed on isolated stone foundations which allow sliding and thus dissipation of seismic energy. As the displacements in horizontal direction are not hindered, when the earthquake occurs, the upper structure moves, thus dissipating a lot of energy.

Marina Šimunić Buršić, Sonja Zlatović
Typological Evolution of Old Industrial Masonry Buildings in Eastern Canada for Holistic Seismic Assessment, Upgrading and Reuse

Old industrial unreinforced masonry (URM) constructions comprise a significant portion of the existing building stock in Eastern Canada. These complex yet still under-researched structural systems have been increasingly targeted for adaptive reuse projects in recent years. Although repurposing existing edifices is identified by provincial legislation as the way forward to preserve architectural heritage and maximize sustainability, the 2020 National Building Code of Canada requires old buildings undergoing major renovations to be seismically evaluated as modern ones. Despite the vulnerability of old industrial URM buildings to earthquakes, scarce knowledge and lack of ad-hoc seismic assessment and upgrading guidelines local practitioners have often translate in oversized retrofits or demolitions. Such invasive interventions pose a serious threat to Eastern Canada’s built environment. This research uncovers recurrent structural characteristics of Eastern Canada’s old industrial URM buildings, vital yet presently missing data for enabling their holistic seismic assessment, upgrading and reuse. To inform onsite research and testing in the framework of a larger research program at McGill University, a comprehensive archival study was conducted and herein presented that consolidates existing building inventories to identify recurrent construction techniques, materials and key architectural features in different historical periods. Produced outcomes enabled us to classify recurrent structural typologies from an earthquake engineering perspective, as well as to identify a critical buildings representative of Eastern Canada’s trends in Montréal, where most assets are located. Results from our pioneering research will constitute a solid foundation on which to inform local engineers and develop informed seismic evaluation and risk mitigation strategies.

Lucy Davis, Daniele Malomo
The Pombaline Cage (“Gaiola Pombalina”): An European Anti-seismic System Based on Enlightenment Era of Experimentation

On November 1st, 1755, the lower part of Lisbon, a city of medieval character, was badly destroyed by the action of a violent earthquake, followed by a tsunami and violent fires. At the time, the Marquis of Pombal, ruled Portugal, and took several measures to safeguard the inhabitants and rebuild the city. It was decided to rebuild the city on the same site, according to a new urban plan with orthogonal streets. The conception of the new urban mesh was an Enlightenment Era design. The buildings were endowed with a series of unique characteristics, including an anti-seismic wooden structure - the Pombaline cage. This solution sought to resist earthquakes, making the building structure less rigid, aiming at dissipating the seismic energy through the lower weight and elasticity of the wood, the flexibility of the connections between the elements and even the lightening of the massive elements. This way, the total ruin of the building was avoided, in the event of an earthquake, and an interior area was created that could remain intact, serving as a refuge for the inhabitants. This anti-seismic system had great importance and influence in the panorama of engineering history, considering it could be at the genesis of seismic engineering in Europe. The perception that 18th century engineers had of the system to resist earthquakes through flexibility, should be the object of in-depth study, as it could be adopted in the reinforcement of constructions against possible earthquakes, especially the oldest ones, avoiding the introduction of rigid reinforcements in buildings otherwise characterized by their ductility. The present study seeks to explore the performance of this system, and to better understand how the increase in seismic performance is processed through flexibility, instead of the increase of the buildings stiffness.

Jorge Mascarenhas, Lurdes Belgas, Fernando G. Branco, Eduarda Vieira
Fixed-Points Method in Robert Maillart’s Analysis of Rigid Frame Bridges

This paper explains Robert Maillart’s analysis approach – using the fixed-points method – for the Weissensteinstrasse Overpass that he designed in 1938. A brief history and a technical explanation of this method are also presented as background information.The structure of this reinforced-concrete bridge consists of two identical plane rigid frames, each possesses five degrees of static indeterminacy. This bridge was one of the few continuous bridges designed by Maillart. Its long-forgotten analysis method, the fixed-points method, is a geometrical method for the elastic analysis of continuous beams and frames, which addresses the static indeterminacy by means of geometric constraint of fixed points on bending moment diagrams. This method was invented by Christian Otto Mohr for analyzing continuous beams, which was based on the work of Carl Culmann, and then refined and extended by Karl Wilhelm Ritter for the analysis of frames. Ernst Suter then generalized and analytically formulated this method for complex cases. In view of the historical context, this method is of special significance for the history of graphic statics. The history and core techniques of this method, including fixed points, crossing-lines, distribution factor, and virtual lateral constraint, are all outlined. The techniques are illustrated with Maillart’s analysis of Weissensteinstrasse Overpass.

Shuyuan Han, Denis Zastavni
Past Restorations and Current Damages in a Building Affected by Seismic Events (2016): The Stronghold of Arquata Del Tronto (Italy)

The Stronghold of Arquata del Tronto was seriously damaged by the seismic events in 2016. Indeed, the stability of the curtain walls is threatened by cracks in the masonry, and even, in some places, disintegration. The latter is generally attributable to the low-level adhesiveness of ancient mortars but, in this case, it is evident that the washout effect is due to lack of maintenance and to the poor connective construction of walls rebuilt in 1992/93. The damage is generally located in the masonry that was extensively restored in the 20th century and, to a lesser extent, in earlier periods. Such repairs were carried out frequently in an area with strong seismic activity. An analysis of instability is an important key to understanding the stronghold’s construction history. It is also an essential tool to correctly interpreting the structure’s static instability. In order to identify and measure it by means of numerical models, a meticulous in-depth analysis of the stronghold’s construction phases is needed, and this can be carried out through the use of archaeological tools - the stratigraphy of the elevations - and the study of written sources. Only by studying these questions will it be possible to plan accurate measurements and adequate designs for future repairs.

Alberto Grimoldi, Angelo Giuseppe Landi, Martina Adami
Protective Analysis of the Wall Structure of the Evangelical Church of Peace in Jawor from the Mid-17th Century Located in Lower Silesia in Poland

The subject of the study is the Evangelical Church of Peace in Jawor dating from the mid-17th century, built following the Peace of Westphalia. The building was designed by Albrecht von Säbisch and is one of the largest religious buildings of timber-framed structure in Europe. The body of the church is a perfect reflection of its spatial layout. The basilica scheme is clearly emphasized by the elevation of the nave covered with a gable roof, while the side aisles have eaves. The division of the façade in the characteristic “fachwerk” form externalizes the course of the structural elements. The unique interior of the building is designed in the Baroque style. The basic material from which the church was built, and its formal appearance has remained unchanged since its construction. The Church of Peace was inscribed on the World Heritage List of UNESCO in 2001 as a unique testimony of architectural solutions. In this article, the authors present an analysis of the protection of the building's wall structure in connection with an improperly carried out repair of the roof truss.

Jerzy Szolomicki, Maciej Minch
The Mediaeval Cross-Braced Collar Beam Roof Structure Over the Vaulted Chancel of the Cathedral in Kamień Pomorski, Poland

Although there are numerous studies relating to the history of the construction of the cathedral in Kamień Pomorski or to the development of historical roof structures in general, none of them has yet included the roof structures of the cathedral in Kamień Pomorski. This situation has justified the pursuit of architectural and dendrochronological studies in order to learn its history, construction, and carpentry technique. The research on the existing material substance of the roof structure over the vaulted chancel of the cathedral was carried out under the following aspects: load-bearing structure, sides of timber framing, carpentry joints, system of carpentry assembly marks, building material and its processing. The results of these analyses were supplemented and compared with the results of the literature study and dendrochronological research. As a result of these studies, it was possible to establish that the chancel of the Kamień Pomorski cathedral is crowned with a cross-braced collar beam roof structure, which dates back to the first half of the 13th century. It was strengthened, in the modern period and in the 1930s. Despite its age and repairs, the original structure has survived to a great extent. The type of roof structure used above the chancel in Kamień Pomorski - a cross-braced collar beam roof structure without a tie beam - served in the Middle Ages for a specific construction task - the construction of a roof over a vault within its boundaries. A preliminary literature review has shown that examples of such solutions have survived in various parts of Europe to the present day, but only in a small number. In the territory of Poland, it is the only known example of this kind from the Middle Ages that has survived to date.

Ulrich Schaaf, Maciej Prarat, Tomasz Ważny
Exploring the Morphology of Tianjin’s Salt Settlement in the Mid-Qing Dynasty: A Study Based on the Iconography of “Painting of Luhe Duyun”

This study investigates the significant impact of the salt industry on the morphology of historical settlements in Tianjin, which has been underrepresented in previous scholarship. By utilizing the iconological method, the “Luhe Duyun Paiting” painting was analyzed as a valuable source of historical data depicting Tianjin during the Mid-Qing Dynasty. This research combined analysis of local chronicles, salt law chronicles, historical maps, and the painting to demonstrate the central role of salt transportation and salt officials in shaping the city's spatial structure. The salt transportation route served as the axis, and the official salt office was the nucleus of the settlement, leading to the distinctive landscape of the salt industry settlement. The official salt office was also the most prominent structure, and the salt industry had a significant influence on the construction of other buildings and the surrounding landscape. The study emphasizes the importance of the salt industry's impact on the historical settlement morphology of Tianjin and highlights the need for further research to explore its broader influence on the city's social, economic, and cultural development.

Kui Zhao, Zhenhong Luo, Xiuli Zhu, Te Wang
The Importance of Preserving the Structural Concept of Historic Monuments: The Case of the Quinta San José in Azogues, Ecuador

The processes of intervention in architectural heritage assets are preceded by research and technical approaches that, in themselves, are an important challenge for conservation and an essential part for their proper execution. This theme is reaffirmed in the case presented in this document. The Quinta San José in the city of Azogues is a monument of high value for the local community and recognized by the State as national heritage. However, its deteriorated condition, as a result of previous interventions, has caused a high degree of vulnerability and not a few damages to its construction system, with progressive degradation triggered not only by natural causes. In response, the Municipality of Azogues (capital of the Andean province of Cañar, located in south-central Ecuador) promoted the development of a comprehensive recovery proposal, combining wisdom and innovation, preserving its memory, but also characterizing it as a vehicle for sustainable development and applying good practices in heritage management. Quinta San José is the result of a complex conjunction of constructive moments with the use of materials, vernacular technologies and different qualities. Based on its understanding, the presented project proposes specific solutions from consolidations to more radical and complex actions of replacement or re-proposition of elements with better design and resistance qualities, which will be clearly shown as new additions or prostheses that can be read appropriately, without misleading, understanding the heritage itself as a source of creativity.

F. Cardoso, C. Rodas, L. Barrera

Structural Health Monitoring

Ambient Vibrations for the Dynamic Identification of Horizontal Diaphragms in Historic Buildings

The dynamic identification of horizontal diaphragms turns out to be one of the most difficult challenges in Civil Engineering and specifically in the field of Structural Health Monitoring (SHM). Characterising these macro-elements is important for the overall assessment of the building structural behaviour. This information is particularly valuable for unreinforced masonry constructions, often characterized by deformable diaphragms. Ambient vibration testing (AVT) could be very useful to obtain modal parameters without affecting the structure and describing the operating conditions of the entire system. The present work focuses on the AVT and Operational Modal Analysis (OMA) of a traditional Venetian slab, consisting of timber floor finishing with terrazzo flooring, in Ca’Tron, a significant noble palace overlooking on Canal Grande and valuable example of gothic architectural style. The slab was investigated at several acquisition points synchronously recording the response to ambient sources of vibration, through a passive seismic single station. A preliminary rapid processing of the data, through peak picking and Decò methodology allowed the identification of two modes, namely a transversal global mode and a vertical local mode of the floor. Their main modal parameters (i.e. natural frequencies, damping ratios and mode shapes) are presented and discussed.

G. Imposa, A. Barontini, S. Russo, P. B. Lourenco
Structural Assessment of a Masonry Quay Wall in Amsterdam Under Traffic Loading

Canals delimited by masonry quay walls are integral elements of many cities in the Netherlands. Historically built to enable the efficient transportation of goods, today such infrastructure also gives the cities their historical and monumental character. In recent years, many quay walls in the Netherlands have shown substantial deformation and damage, and in few cases even collapse. Historical quay walls, which are constructed in thick multi-wythe unreinforced brick masonry and are supported on a system of timber piles, nowadays sustain traffic loads larger than the one they were designed for. Instances of collapse and severe damage has given rise to a need for research assessing the safety of these structures, which are not appropriately covered by any normative or standardised guidelines. This paper presents a novel methodology to numerically assess the performance of masonry walls in historical quays under the dynamic effect of traffic loads. Application of the proposed methodology to a case study in Amsterdam, the Netherlands, is presented.

Satyadhrik Sharma, Michele Longo, Rita Esposito, Francesco Messali
Results from the Seismometric Continuous Monitoring of an Ancient Bell Tower: The Arnolfo Tower, Palazzo Della Signoria, Florence, Italy

Florence (Tuscany, Italy) is one of the most visited cities of art in the world. Monuments, buildings, masterpieces from Renaissance are distributed everywhere in the historical center and they constitute an important heritage that is both of cultural and economic interest. It is of great importance to preserve the historical and cultural heritage of the city which constitutes an enormous wealth for the community.The first action for the protection of cultural heritage buildings is to increase the knowledge of their elastic characteristics. This allows to compensate for the lack of information regarding materials, construction techniques, and the geometries of the walls. In this context, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Dept. of Architecture of the University of Florence (DIDA) in December 2021 undertook a long term seismometric monitoring experiment, still in progress, of the Arnolfo Tower, the bell tower of the Palazzo della Signoria, the historic building that houses the Municipality of Florence.Two seismic stations were installed at the base and on the top terrace recording free vibrations to estimate the modal parameters of the structure. During the monitoring period, a short seismic sequence occurred which produced about more than 200 earthquakes with a maximum magnitude of 3.7, located about ten kilometers from the city and strongly felt by the population.The analyses of free vibrations made it possible to identify the main modal frequencies which constituted the experimental constraints for the comparison with the numerical model of the Tower. Continuous monitoring allows to record also moderate earthquakes than can produce effect on the structure, the results of the analysis of the seismograms recorded is presented.

R. M. Azzara, M. Tanganelli, F. Trovatelli, N. Vettori
Deep Learning-Based YOLO Network Model for Detecting Surface Cracks During Structural Health Monitoring

Detecting surface cracks and identifying their severity are crucial steps in the structural health monitoring of historic buildings. In the field of heritage preservation, crack formation and other related defects are substantial flaws because they significantly affect the long-term durability of historic structures. In this study, an automated method based on the deep learning (DL) object detection model, You Only Look Once (YOLOv5), was deployed. It captures and pinpoints cracks in masonry structures via bounding boxes. The developed DL model was trained using 4000 annotated images collected using a mobile camera from different historic sites in Bhubaneswar, Odisha, India. The training time of the model was relatively short, which led to low computational costs of numerical simulations. The developed YOLOv5 model achieved a mean average precision (mAP_0.5) of approximately 92% on the collected masonry crack database. Unlike other contemporary DL models, this model can be used for real-time health monitoring. The findings of this study provide insights for identifying structural problems that require immediate repair, enabling improved monitoring and inspection of historic buildings.

Kumari Pratibha, Mayank Mishra, G. V. Ramana, Paulo B. Lourenço
Research on Optimal Sensor Placement Method of Traditional Chinese Timber Dwellings Based on Multi-objective Monitoring

Traditional Chinese timber dwellings have high historical value, artistic value, and scientific value. The complex architectural form necessitates great challenge to the sensor placement. The case study of Number 21 Hall, a dwelling building located in Fujian Province (China), is investigated. An improved genetic algorithm is used for the multi-type and multi-objective optimal sensor placement of traditional Chinese timber dwellings. Firstly, the optimization objective function of multiple monitoring objectives is developed, considering the aim of the parameter identification, damage detection and information redundancy. Then, the improved genetic algorithm is used to search the optimal degree-of-freedom in the global space to determine the optimal sensor placement. Finally, the optimized sensor placement is determined. The results show that, the priority of acceleration sensors arranged on the roof beams of the main-room in Number 21 Hall is the highest, the priority of strain sensors placed at the foot of the column which located in junction area of the main-room and wing-room is the highest, and the tilt sensors should be placed at the beams near the top of columns. The research can provide scientific basis and valuable contributions to the optimal sensor placement in the structural monitoring of historical buildings.

Chengwen Zhang, Qing Chun, Yijie Lin, Yuchong Qian, Guang Cao, Qingchong Dong
Static and Dynamic Monitoring of Giovanni Pisano’s Pulpit in Pistoia (Italy)

Structural Health Monitoring (SHM) procedures are assuming increasing importance in the field of preservation of Cultural Heritage (CH) structures. These structures face the consequences of ageing and incorrect repairs operated in the past and their conservation remains of upmost importance to preserve their inherent cultural value. In particular, statues or other artifacts composed of an assembly of rigid blocks have invaluable historical and artistic significance, and the application of SHM systems can provide information on their structural state and detect the presence of anomalies.The present work discusses the static and dynamic monitoring system installed on the pulpit in the church of Sant’Andrea in Pistoia (Italy), a medieval masterwork by the Italian sculptor Giovanni Pisano. The monitoring system is aimed at providing real-time structural performance monitoring and trigger warnings. Minimal invasiveness and interference with operational conditions were essential aspects considered for its design, to obtain a balance between structural assessment needs and respect for architectural and cultural value of the structure. After specific information about the pulpit geometry, the damage state and the description of the monitoring system installed, the paper presents a summary of the results from data analysis carried out on environmental, static, and dynamic measurements on the first six months of monitoring.

Francesca Marafini, Michele Betti, Gianni Bartoli, Giacomo Zini, Filippo Casarin, Fabio Marchesini, Alberto Barontini, Nuno Mendes
Preliminary Interpretation of the Data from the Static Long-Term Monitoring System on the Asinelli Tower in Bologna, Italy

Structural Health Monitoring plays a very important role in the diagnostic process of existing structures, and especially for historical and cultural buildings, whose structural behaviour is generally affected by significant uncertainties that render each structure “unique”. If properly associated to an extensive knowledge of the materials and the structural layout, it represents an important tool to obtain precious information regarding the time-evolution of some significant response parameters and thus estimate the future behaviour of such buildings, also helping the owners in management and "decision making" activities for maintenance and interventions. The inherent complexity of historical buildings, together with the natural material decay and the effects of natural and anthropic hazards (extreme weather events, earthquakes, traffic vibrations, etc.), make the assessment of their “structural health” not only extremely challenging but also actually essential for their conservation. In this respect it is fundamental to monitor their conditions, to know the time evolution of their safety level, in order to implement economic and efficient retrofit interventions. In this paper, an example of the application of the Principal Component Analysis (PCA) on the data collected by the SHM system installed on the Asinelli Tower in Bologna (Italy) in the last decade is presented. This allows to assess the main information hidden in the recorded data, to identify the evolving trend of some response parameters, and to compensate the effects of the temperature. The methodology applied in this paper might be useful in the future monitoring activities in the development of threshold values for the assessment of sound and reliable safety levels of the Tower.

Matteo Marra, Emma Ghini, Michele Palermo, Stefano Silvestri, Giada Gasparini, Sérgio Bouça Pereira, Filipe Magalhães

Inspection Methods, Non-destructive Techniques and Laboratory Testing

The Use of New Ultrasonic Pulse Echo Tomography in Historic Structure Applications

Nondestructive evaluation methods involving ultrasonic pressure waves have been used in modern and historic masonry investigations for many years. However, these methods (impact-echo and ultrasonic pulse velocity) have generally been limited to gathering information along a single ray path at a time. Tomographic software has been available for many years to post-process ultrasonic data, but this process was generally not automated, and it did not provide immediate feedback. With the advent of inexpensive and accessible computer processing power, several companies have introduced ultrasonic pulse echo arrays that collect and process tomographic images of subsurface conditions instantaneously. These arrays are often advertised for use in the location of subsurface conditions such as plastic electrical conduit and prestressing tendon grout in modern concrete structures. However, due to the use of ultrasonic waves and the ability to perform testing with access to one side of a structure only, this tool provides several unique capabilities in the investigation of historic structures.This paper describes some of the distinctive types of investigation available with new ultrasonic pulse echo array technology for historic structures. Several case studies will be included that illustrate the advantages and limitations of this equipment in the context of historic structures. Case studies include investigation of stone roof elements, cracking due to anchor corrosion, mortar joint conditions, and stone delamination.

Donald W. Harvey, Gary D. Ogden
Evaluating the Energy Performance of Historic Buildings: Experimental Methodology for the Analysis of Heat Transfer in the Surface Boundary Layers of Wall Assemblies

Energy performance represents a major focus in building engineering, with an increasingly marked urgency arising over the last decades due to growing environmental concerns. The European Union nowadays stresses the importance of energy efficiency and decarbonisation of the existing building stock through the implementation of adequate mitigation strategies addressing climate changes and energy transition [1]. In this perspective, historical constructions, constituting a conspicuous percentage of the built environment, are very relevant and present indeed huge energy-saving potential. This study aims at evaluating the energy performance of buildings with particular insights on adequate optimisation of thermal insulating capabilities of historical constructions. More specifically, the paper focuses on ongoing experiments carried out in a climatic wind tunnel, based on past results [2, 3], where several types of building envelopes are tested monitoring their responses to realistic climatic scenarios. The experimental data obtained ensure describing the interrelationship among various parameters such as temperature, relative humidity, wind velocity and direction as well as heat fluxes in the building component and surface roughness. The main objective is to describe the heat transfer in the mixed velocity-thermal boundary layer near the envelope surfaces. For that purpose, convective heat transfer coefficients for various types of envelopes are determined under different environmental conditions using a combined experimental-computational method, as in e.g. [4]. The obtained outputs are exploited in energy simulation models and heat transfer simulations to achieve higher accuracy than standardized methods. Future work is also outlined in the perspective of bettering energy performance and its evaluation in historic buildings.

Arsenii Trush, Riccardo Cacciotti, Stanislav Pospíšil, Jan Kočí, Tomáš Navara
Modeling a Maintenance-Focused Conservation System

There are several intervention approaches that can be applied in heritage conservation; from reconstruction, restoration, repairs to a do-nothing approach. This paper examines whether maintenance is more than an option, but rather a necessity. The aim of the study described in the paper is to propose a framework which puts more emphasis on maintenance in conservation. This research was conducted in an Australian context, where many major buildings are categorized as being ‘modern heritage’. However, the main problem with modern heritage is that although it has become more eminent, maintenance is still on the backseat of most facility management operation, its importance has yet to become a potential solution that will tremendously aid in properly preserving a nation’s architectural legacy. Challenges were evaluated and opportunities were identified in order to highlight the necessity of including maintenance approach in preserving historical fabric in heritage conservation. This research examines the key strategies in order to develop a maintenance-focus conservation system.

Arturo Cruz, Vaughan Coffey, Tommy H. T. Chan
Case Analysis of Non-destructive Testing for Historical Timber Structures in Shanghai

Timber is one of the widely used construction materials in historical structures all over the world. After many years of use, defects such as decay, termite infestation, and cracking are quite common, and the strength is difficult to estimate. Non-destructive testing methods play an important role in the safety assessment and historic preservation. Several timber structural inspection projects of historical buildings in Shanghai are presented in this paper to demonstrate the application of non-destructive testing methods such as the drilling resistance method and the endoscopic method. The estimation of the timber strength grade is introduced and compared with the timber species. The feasibility of the detection methods is analysed based on the testing results. Analyses results indicate that the drilling resistance method can reasonably demonstrate the location and geometry of internal defects for timber structures of historical buildings. The resistance value of timber members after fire is measured by the drilling resistance method. The peak value of resistance curve of the slightly carbonized part decrease insignificantly, and the peak value of the severely carbonized part is significantly lower than that of the undamaged part. The amplitude of the resistance curve of the internal uncarbonized part was close to that of the undamaged part. The endoscopic method can reasonably characterize the internal damage of timber members and mortise and tenon joints, and the geometry details of mortise and tenon joints can be measured. The comprehensive ultrasonic-drilling resistance method is feasible in estimating the strength grade of timber. The research results can provide technical support for the non-destructive testing for historical timber structures.

Xi Chen, Zhuolin Wang, Mingqian Wang, Yubing Leng, Lingzhu Chen, Qingfeng Xu
A Mineralogical Study of 350-Year-Old Historical Mortars for Restoration Purposes: The Case of the Castle of Good Hope (Cape Town, South Africa)

The restoration and conservation process of structures of historical significance, specifically the mortar, is complex. This is mainly because historic structures symbolize many countries’ backgrounds and historical events. Hence, caution is always necessary to preserve their authenticity. For the ultimate results of historic restoration activities, there are several aspects to consider, such as compatibility, retreatability, reversibility, and durability. These are achieved through original mortar characterization beforehand. The original material analysis has been well received and explored worldwide; however, the African continent is yet to invest more research on this concept for sustainable restoration projects. To address the long-existing challenge and make informed decisions on suitable restoration mortars for future restorers, a reverse engineering approach, by means of physical and mineralogical analysis of original historic mortars from the Castle of Good Hope, a 350-year-old colonial structure located in Cape Town, South Africa was conducted. As part of the preliminary investigation on original mortar characterization for restoration interventions, this paper reports on the aesthetic, physical and mineralogical properties of samples collected from the oldest section of the Castle. A semi-quantitative analysis employing colorimetry, mercury intrusion porosimetry, powder x-ray diffraction and thermogravimetric-differential scanning calorimetry was carried out. The physical and mineralogical analysis show original mortars for this structure to be mainly whitish to cream lime-based with porosity ranging between 20–38%. The samples observed under XRD included, on average 64% of calcium carbonate (calcite) phases, 19% average peaks representing quartz, 3% gypsum and other minerals such as microcline, albite and biotite. The earth mortars showed prevalence of quarts (88%) and kaolinite in the range of 9%.

Maphole E. Loke, Giuseppe Cultrone, Kumar Pallav
Preliminary Experimental Investigation on Mechanical Properties of Historical Fibrous Plaster

Fibrous plaster (FP) is a natural fabric-reinforced composite material. It has been widely used to produce decorative suspended ceilings in high-profile historical buildings in the UK since the late 19th century. The constituent materials of FP are plaster of Paris (POP) and woven jute fabrics. Despite its prevalence, FP has been neglected in scientific research, which makes the associated structural assessments challenging. Recent collapses of several historical suspended FP ceilings highlight the need to characterise mechanical properties of FP and structural behaviours of historical FP suspended ceilings. However, the lack of research on historical FP’s constituent materials is a significant challenge, making material characterisation research necessary. This paper characterises physical and mechanical properties of historical and new POP and jute fabrics. Specimens were prepared from historical FP suspended ceilings of the Institution of Civil Engineers (ICE) building in London while commonly used modern repair materials were used for the new specimens. For POP, compression tests and impulse excitation of vibration (IEV) tests were performed to characterise mechanical properties. For jute fabrics, single yarn tensile tests were performed to characterise mechanical properties. Optical microscope, micro-X-ray computed tomography (µ-XCT), and moisture analyser were used to obtain physical properties including diameters of single fibres and yarns, fibre volume ratio of yarns, and the water content of yarns, respectively. By comparing the results from historical specimens with those obtained from new specimens, modern constituent materials that can be used for further investigations of FP are identified.

Jiaxu Zuo, Sarah Mayfield, Anil Ozdemir, T. James Marrow, Brian Sheil, Sinan Acikgoz
Experimental Assessment of Three Simple Techniques for the Seismic Retrofitting of Heritage Earthen Structures

An experimental program was conducted to evaluate simple retrofitting techniques that could preserve historical buildings in Colombia. This paper presents experimental results from 28 full-scale adobe and RE walls subjected to in-plane and out-of-plane lateral cyclic loading, overturning, and shake table excitations. Geometries included solid walls, wall piers, flanged/corner walls, and walls with openings. Specimen dimensions were 0.4m or 0.6 thick, 1.25 to 7.0m long, and 1.8 to 3.45m tall. It was found that retrofitting with steel meshes can enhance the lateral load capacity of earthen walls by as much as 190% and drift capacity by as much as 170% depending on the level axial load. Flanged/corner RE walls that failed under the design-level earthquake were able to sustain much larger levels of excitation when retrofitted with steel meshes although exhibiting excessive residual drifts. Retrofitting with steel plates increased the in-plane shear strength of adobe wall piers by 30% and enabled attaining drift ratios of up to 5% under out-of-plane cyclic loading. Steel plates also allowed corner RE walls to sustain base excitation well-above the design earthquake while maintaining residual drifts at tolerable levels. Using timber straps and vertical posttensioning was the most effective seismic retrofitting alternative evaluated in this research because the in-plane lateral resistance of earthen walls with openings increased by almost 80%, while the drift capacity increased by a factor of five, and the energy dissipation capacity increased by nearly an order of magnitude. Flanged RE walls retrofitted with timber sustained very large levels of base excitation with minimal permanent drifts .

Juan C. Reyes, J. Paul Smith-Pardo, Wael M. Hassan, Juan D. Sandoval, Cristian D. Gonzalez
A Strategy of Optimal Sensor Placement for Dynamic Identification in Cultural Heritage

The present study describes an approach to boost the cost-effectiveness of the Operational Modal Analysis (OMA) application to historic buildings, through the optimisation of the trade-off between the number of required sensors and the quality of the information provided by them. Such an approach, currently under development and testing, considers a limited level of knowledge and relies on extensive simulations to assess the effect of the sources of uncertainties on the dynamic behaviour of the structure. In particular, the work focuses on a specific building typology, namely the noble palace overlooking Canal Grande in Venice, dating back to Gothic period. To this end, a prototype is defined based on the most relevant typological and morphological features of this typology, and its Finite Element (FE) model is generated. A Monte Carlo simulation technique is employed to sample several different instances from pre-set probabilistic functions for each stochastic variable. An Optimal Sensor Placement (OSP) algorithm is used to rank different recommended locations for a reduced number of sensors under these parameters’ variation, producing an optimal overall topology for the network. These considerations open future developments in view of a possible protocol applied to this historical building typology.

G. Imposa, A. Barontini, P. B. Lourenco, S. Russo
Strength of Dvāravatī Fired-Clay Bricks Related to Mineral Components in Fa Daed Song Yang and U Thong Ancient City, Thailand

A comparative study on mineral components and strengths of ancient fired-clay bricks in Dvāravatī Period is conducted on Fa Daed Song Yang (FDSY) and U Thong (UT), Thailand. The FDSY ancient city is now located in Kalasin Province, northeast Thailand. The UT ancient city is currently situated in Suphan Buri Province, central Thailand. These ancient brick remnants were sampled for comparative analysis to obtain information on mineral components and mechanical characteristics. The primary conclusion of the FDSY ancient bricks is that their strengths are regulated by the quartz-tridymite-cristobalite phase transformation of 57–69% and also clays of biotite, clinochlore, kaolinite, and muscovite of 15%. They show apparent plastic deformation with a yield strength of 1.0–1.6 MPa and elastic modulus of 100–230 MPa. The uniaxial compressive strength of the UT ancient bricks depends on quartz group under quartz-tridymite-cristobalite and also coesite-stishovite phase of totally 81–91%. Clay components in the UT similar to the FDSY are found in the range of 1–4%. Yield strengths and elastic modulus of the UT are present at 1–3 MPa and 247–291 MPa, respectively, which are higher than the FDSY bricks. The compressive strengths and mineral components of both ancient bricks are related to the firing temperature at 1,000–1,200 ℃. Mineral characteristics in the FDSY bricks presented by low silica group and high clays indicate sediment trapped in placid lakes. Their contents are inversely proportional to the UT bricks which are referred to sediments in mighty rivers and deposited in delta/estuary with very fine sand accumulation.

Sarunya Promkotra, Kritika Trakoolngam, Thidarat Cotanont, Tawiwan Kangsadan
Innovative Application of Self-healing Technology to Masonry: A Proof of Concept

Cracks are one of the most common expressions of damage in masonry structures. Aside from aesthetic issues, they can compromise the overall behaviour of the structure; therefore, they are undesirable and need to be repaired. The repointing technique is traditionally implemented in this context, especially in historical masonry. Nevertheless, future damage is not prevented and may arise again, thus requiring renewed repointing interventions.The paper describes a preliminary study conducted at Delft University of Technology to investigate the applicability of the innovative self-healing technology to enable an automatic repair of masonry cracks. A bacteria-based self-healing mortar, developed to repair existing concrete structures, was implemented to explore the capacity of couplets to recover their original strength and aesthetic aspect after multiple damaging events. Specimens built with calcium-silicate and clay bricks were subjected to subsequent cracking cycles using a crack-mouth-opening-displacement controlled bond-wrench test.Experimental results showed that self-repair, in terms of strength restoration and aesthetic filling of cracks, occurs even after multiple cracking cycles when the self-healing mortar is used with both types of bricks, optimizing the autogenous healing of cement-based mortars. In this context, the healing effectiveness tended to decrease as the crack width and the number of cycles increased. The effectiveness varied also according to the types of brick and healing environment used, e.g. under humid conditions (RH ~ 95%), 50% vs 80% of the original capacity was regained in fully separated couplets made respectively with clay and calcium-silicate bricks. This outcome provides the ground to delineate the remaining testing campaign.

Maria B. Gaggero, Paul A. Korswagen, Rita Esposito, Jan G. Rots
Primum Non Nocere. Digital Radiography (X-Ray) of the Plafond (“Aurora”), by Jean Pierre Norblin De La Gourdaine, in Light of the Multifaceted Conservation Issues of the Temple of Diana in Arkadia

This article presents the reasons initiating the search for new X-ray imaging solutions for the recognition and prevention of the monument in the light of a retrospective of the ongoing conservation, renovation and construction activities at the world-class building of the Temple of Diana in Arkadia, including the priceless “Aurora” plafond by Jean Pierre Norblin de la Gourdaine. It shows how the state of preservation of wall paintings is inextricably linked to the state of preservation of the building and the environmental conditions within it.The issues presented point out to the benefits of the implementation of modern, non-invasive imaging techniques, even in such complex conditions of access to the examination site in the spatial layout of the architecture. After analyzing the architectural plans of the Temple of Diana, X-ray imaging of the plafond of selected parts of the composition was performed according to the developed examination methodology. A methodology for imaging the entire painting was also prepared, allowing the examination of any size part of the plafond, depending on the needs and possibilities for the implementation of the undertaking. High-end X-ray equipment with digital recording of the results, in fact, gave the possibility of very accurate recording of the state of preservation of the painting at the level of its carrier – the substrate made of various materials of plaster, wood and metal. Such records are used for comparative analysis of the condition assessment of the plafond after a repeated examination performed at the same site, which is a monitoring activity that influences the taking of preventive measures. The X-ray examination results proved to be helpful in light of emergency rescue works that allowed the dome to be decompressed and damaged beams to be replaced. The cooperation of specialists from a number of fields made it possible to develop a program and introduce measures to monitor the state of preservation of the painting's bearing structure necessary in connection with the roof replacement.

Dorota Ignatowicz-Woźniakowska, Maria Kurpik, Łukasz Kownacki
Experimental Understanding of the Technology of Sgraffito Decorated Renders

Sgraffito technique was used to decorate renders by scratching the top layer of lime coat in the Renaissance time. This technique required both artistic and craft skills and its quality and durability relied on the selected materials. This type of decoration typically consists of geometric ornamental patterns symbolizing masonry blocks and other architectural tectonic features as well as figural depictions of various religious and profane motives. The main conservation issues currently relate to delamination of the render layers from the substrates, surface weathering and loss of drawn details, and incompatible and insensitive previous repairs. All sgraffito facades that have been exposed are nowadays either deteriorated or restored. Sgraffiti preserved in their authentic form exist only when covered by later render layers or sheltered by adaptations. An experimental approach was employed to improve understanding of the original Renaissance sgraffito technique based on the creation of a technological replica of an authentic sgraffito from Slavonice. It aimed to guide the repair mortar formula and its application. It has shown that the raw materials used influenced the engraving method, troweling and shading, line thickness, color and texture. Practical trials brought important findings on the technique including verification of the shading method. The study of the technological aspects complements the compatibility and performance requirements of the repair materials.

Jan Válek, Zuzana Wichterlová, Jana Waisserová, Petr Kozlovcev, Olga Skružná
Influence of the Distance from the Pith in Resistance Drilling Tests on Timber Beams

Resistance drilling test is commonly employed to evaluate the state of preservation of historic timber. Results are mainly qualitative, owing to the heterogeneity of the material and the localized inspection. Notwithstanding, a quantitative parameter (RM) can be adopted, so that different tested areas can be compared. Many factors can modify the test results, e.g., wood species, drilling settings, defects, and degradation. In the paper, the results of an experimental campaign on timber beams, aimed at evaluating the influence of the test-to-pith distance on the outcomes of the resistance drilling test, both from qualitative and quantitative points of view, are discussed.Firstly, a spruce new sawn timber element was tested; 55 tests were carried out with constant settings of the drill and following a predefined grid. The specimen was then sliced along the rows of the grid. The drill needle tended to deviate from the orthogonal direction as it crossed the rings tangentially, and the distance from the pith increased. The highest values of RM were obtained for those tests closer to the pith. On average, the feed RMs for the central ward were 21% higher than those on the extreme wards of the cross-section, whereas the drilling RMs resulted 10.4% higher.This study was then extended on a sample of 24 old and new timber beams, for a total of 440 tests. Results were aggregated as a function of the distance to the pith. On average, tests carried out close to the pith yielded RM values 9% higher than those on the neighboring ward, and 22% higher than those on the outer wards.

Maria Rosa Valluzzi, Ylenia Saretta, Elvis Cescatti
Transformation of Hydraulic Binders Over Time: Analytical Insights

Thermogravimetric analysis, scanning electron microscopy and mechanical strength measurements were used to describe the changes in cementitious mortars caused by the action of liquid water and carbon dioxide over time. Model lime-cement mixtures were exposed to three different regimes of artificial ageing – (1) exposure to CO2 and humidity, (2) exposure to CO2 and (3) exposure to humidity. Although the effect of different ageing regimes showed similar trends (carbonation and subsequent decalcification of clinker residues), the combination of CO2 and humidity had the strongest impact on the samples. Total carbonation and the separation of the binder to newly formed CaCO3 crystals (including metastable vaterite or aragonite) and amorphous silica-rich structures were observed. Flexural strength decreased slightly for all samples. The most significant decrease was determined for mortar affected by both increased humidity and CO2.Apart from artificially aged model samples, the changes in two authentic 120-year-old mortars from the inner parts of Most Legií bridge, Prague, were studied. Their binder was identified as early Portland cement. The mortars showed a different degree of carbonation and the formation of metastable CaCO3 polymorphs (vaterite and aragonite) or imperfectly crystallised calcite. This can be explained by the low CO2 access within the inner structure of the bridge’s construction.

Dita Frankeová, Pavla Bauerová, Zuzana Slížková, Daniel Dobiáš, Milan Hrabánek
Rules of the Art and the Non-standard Behaviour of Masonry

The paper presents a series of tests made on simple block structures with a DIY shaking table. Details are first given about the rig and the experimental setup. Besides providing information useful to understand the purpose and condition of the experiments, the aim of this first section is to discuss changes introduced in hardware and software (since its first presentation) and to describe how footages taken during the experiments were processed using OpenCV. The section may be of interest to anyone interested in low-cost shaking tables. The second section presents two series of tests: a first one, static, during which the abutments of the block structures are subjected to differential displacements, and a second one, dynamic, during which the same block structures are subjected to short Morlet-type wavelets impulses. The structures were designed to be as elementary as possible to clarify the effects of limited friction, wedging, and bounds on the normal forces. These factors are important for masonry structures as they are related to their non-standard behaviour. The first series of static tests is compatible with previous analytical research, showing how bounds on the normal forces acting on joints can be used to build safe domains. The second series of dynamic tests led to a very different outcome. Both confirm the difficulty of mathematical modelling and the importance of the rules of Art used in masonry constructions. They contribute to safety and often justify the trust that analysts can have in simplifying assumptions (when they are followed).

Pierre Smars
A Modified Virtual Fields Approach to Identify the Mechanical Properties of Mortar in Existing Masonry Structures Without Loading Information

Identifying the mechanical properties of mortar in existing masonry structures is challenging. While units can be extracted and tested in the laboratory for identification purposes, sampling of mortar is often unfeasible. This paper develops a new in-situ identification procedure for mortar, using surface strain measurements and knowledge of the mechanical properties of the unit. It makes use of the Virtual Fields Method (VFM) algorithm, which enables the direct identification of material characteristics from strain and loading information. In this new application, the VFM is modified to identify the mechanical properties of mortar using unit properties only, without recourse to loading information. This treatment helps eliminate the significant loading uncertainties encountered during flat jack tests. To explore the feasibility of this approach, a three-dimensional finite element model with a microscale representation of a brick masonry wall is constructed. Bricks and mortar are assigned isotropic and linear elastic material properties. Overburden and in-situ flat jack loads are applied. The resulting surface strains due to jack loading are obtained; these simulate full-field measurements that can be obtained using Digital Image Correlation. The modified VFM approach is then applied, where an excellent agreement was obtained between the estimated and true Young's modulus of the mortar. The influence of errors in unit properties and measurement noise on identification results was quantified and indicate the robustness of the identification procedure.

Miles R. W. Judd, Marialuigia Sangirardi, Sinan Acikgoz
Determining the Young’s Modulus of Lime Mortar Using the Virtual Fields Method

Lime mortars are widely used to repair and retrofit historic masonry structures. There are well-established testing procedures to determine their compressive and tensile strengths. However, there is no consensus amongst practitioners and researchers on the appropriate method to determine their Young’s modulus. In current practice, this parameter is either derived from (i) dynamic response measurements conducted during impulsive excitation and ultrasonic wave transmission tests, or (ii) from limited strain and load measurements obtained during cube and cylinder compression tests. Both strategies have some drawbacks. Dynamic tests operate in the very small strain range and tend to overestimate Young’s modulus. On the other hand, conducting mechanical identification by interpreting limited strain and load measurements using uniform stress and strain assumptions may not yield reliable results. In this paper, we determine the Young’s modulus of lime mortar using an inverse method called the Virtual Fields Method (VFM). This method calculates elastic constitutive parameters directly from full-field surface strains (obtained using Digital Image Correlation) and total load measurements. Different from existing techniques, it enables rigorous consideration of the heterogenous strain fields that arise during testing. To compare methods, identification results obtained for cube shaped natural hydraulic lime samples are compared in this study. The preliminary results demonstrate how VFM provides more appropriate estimates for the Young’s modulus of lime mortar compared to existing methods. Results also highlight factors which contribute to errors in VFM identification results. A brief discussion presents possible methods to further improve identification results.

Marialuigia Sangirardi, Miles R. W. Judd, Anil Ozdemir, Sinan Acikgoz
A Method to Generate Realistic Synthetic Point Clouds of Damaged Single-Span Masonry Arch Bridges

Masonry bridges form an important component of the transport infrastructure in the UK and Europe. Structural issues in these bridges are often identified by the presence of visual surface defects, such as cracks. To automate this process, recent research efforts have focused on identifying defects from images, neglecting the potential information that can be gained from investigating accompanying geometric distortions. To explore the feasibility of using geometric distortions to identify cracks, a large synthetic point cloud dataset of single-span masonry arch bridges is developed in this study. For each bridge, a macro-scale nonlinear 3D finite element model is first created. Using the wide range of geometric and material parameters that characterize masonry arch bridges, finite element model generation process is randomized and automated. Batches of finite element calculations are subsequently performed to extract distorted bridge geometries arising from a range of commonly encountered differential settlement profiles. The distorted geometries are then imported into a 3D graphics environment, where they are converted into point clouds by considering realistic scanning geometries and measurement noise. This step closely simulates the laser scanning of bridges as a part of routine inspections and enables the generation of a large and high-fidelity point cloud dataset. With a simple example, it is demonstrated that by investigating geometric surface features, such as mean surface curvatures, cracks can be identified. Future work will utilize the dataset developed in this study to train neural networks to identify defect locations, quantify their magnitude and diagnose causes of structural damage, directly from point clouds.

Yixiong Jing, Brian Sheil, Sinan Acikgoz
The Rehabilitation and Extension of the Old Arad’s Casino – Case Study

The Arad Casino is a historical building, built in 1872, known as “The old Casino” and is listed as a monument of local importance. It has an architecture with neoclassical and neobaroque elements and, since its inauguration, has become an attraction of the city. In the twentieth century, people frequented the casino to play roulette or blackjack. But they did not just come here to play at the casino, there were all kinds of events and exhibitions were organised inside the building. In 1910, the first restoration took place, the extension of the building, and the construction of the first outdoor skating rink around the casino. During the summer, people also preferred to sit in the garden near the casino. Unfortunately, however, the Arad casino has deteriorated considerably in recent decades. After 1990, it became privately owned, and in 2007 a restaurant and a club operated here. Subsequently, the building was abandoned and under these circumstances many objects were destroyed over time and required massive repairs. Since 2017, the casino owner has become a private company, and restoration works have started with the main purpose of reusing the casino as an event space for private and public events, bringing the previous luxurious interiors back to life. The project had to deal with urban constraints, the site being specific defined through the urban planning zone of the central protected area of Arad. Other constraints came from structural, finish, or paint damage (even graffiti). Even the need of the owner to maximize the space to amplify its potential was also a specific requirement.This paper presents the final solution of interventions from both architectural and structural point of view, considering the monumental character of this construction, all kinds of constraints, according to the authorities’ requirements (Ministry of Culture, Arad City Hall) and the demands of the owner. The paper’s methodology consists of presenting existing data, historical and contemporary, followed by the architectural and structural interventions on the monumental building.The research objectives on this case study were achieved demonstrating the positive impact of a good intervention for the whole community.

Catalina M. Bocan, Dragos P. Bocan, Mihnea H. Truta
Experimental Investigation on Size-Effect of Rubble Stone Masonry Walls Under In-Plane Horizontal Loading: Overview and Preliminary Results

Rubble stone masonry is a common construction typology of historical city centres and vernacular architecture. While past earthquakes have shown that it is one of the most vulnerable masonry construction typologies, there are few experimental campaigns giving quantitative information on the strength and displacement capacity, as well as on the damage pattern under in-plane horizontal loading. Additionally, there is a lack of experimental studies looking into the role of the size of the structural element on the structural response of rubble stone masonry walls.This paper presents an experimental campaign for testing the in-plane seismic response of rubble stone masonry walls and developing digital twins for their numerical simulation. Nine rectangular walls of three different sizes were constructed by experienced masonry using irregular limestone units and lime mortar. The mechanical properties on the unit and wall level were obtained through mechanical characterization tests on mortar samples and wallets. The walls were tested at the laboratory of EPFL (Switzerland) under quasi-static loading using the same load and boundary conditions. All walls were tested up to axial load failure (i.e. up to the point where the walls cannot bear any vertical load), providing information on the drift levels at collapse of the wall. Digital image correlation measurements were used to obtain displacement fields and extract crack patterns during the load history. The results of this experimental campaign offer a first insight on the size effect on the in-plane response of rubble stone masonry walls.For the purpose of validating numerical modelling techniques for stone masonry structures, we developed the geometrical digital twins of three of the tested walls. Each geometrical digital twin represents a numerical replica of the physical specimen, generated with a pipeline based on laser scanning. In this way, the experimental and numerical datasets are valuable for the calibration of numerical models for rubble stone masonry and for further numerical investigations of the size effect.

Savvas Saloustros, Katrin Beyer
Non-destructive Testing on Old Masonry Wall of Non-pareille Manor House, South Africa

This research investigates the mechanical properties of the old masonry gable wall of the 196-year-old Non-Pareille Manor House, an excellent example of Cape Dutch architecture. The manor house is classified as a Grade 1 heritage resource by SAHRA, the highest level of significance in South African heritage. The mechanical properties of the front gable wall of the Non-Pareille manor house have been determined through non-destructive testing. The testing methods used in this research are rebound hammer testing and ultrasonic pulse velocity testing. The surface level compressive strength has been determined through rebound hammer testing, following calibration through site sample crushing in a laboratory. Poisson’s ratio and Young’s Modulus for the masonry have been calculated from ultrasonic pulse velocity test results. From visual inspection, severe cracking above the door opening has been noted and remediation is recommended to avoid further crack opening. The compressive strength distribution indicates a higher strength at the center wall panel, with a higher Young's modulus and a lower Poisson's ratio. Increased cracking has been noted on the right wall panel, corresponding with a lower compressive strength, Young's modulus, and a higher Poisson ratio. The study achieves results through the development of a testing methodology that is unique in the field of the conservation of heritage structures in South Africa. The method can be further incorporated into other heritage structures in South Africa to sufficiently describe the mechanical properties and aid in the development of suitable conservation plans.

R. J. Victor, K. Pallav
Experimental Investigation of One-Sided Strengthening Interventions on Historic Brick Masonry Walls

The conservation and restoration of historic buildings is a complex problem that requires an interdisciplinary approach in order to increase the bearing capacity of the structure while preserving the authenticity and aesthetics of the building.Despite its high diversity of built heritage, the city of Timisoara, located in the western part of Romania, presents heritage buildings in a bad state of conservation, with significant decays of the exterior render. In order to preserve the identity of the historic part of the city, measures have to be taken soon. Since commonly used strengthening solutions can alter the aesthetics of buildings and insulating materials can cause multiple problems, other solutions had to be taken into consideration.One particularity of Timisoara and Romania, in general, is that almost all apartments in historic buildings are privately owned, with each apartment having a different owner. This makes interventions that affect both sides of the external walls difficult. Therefore, a decision was made to investigate the effect of strengthening solutions applied only outside, as the owners rarely agree to move out of the building while interventions are made. To investigate the effect of the considered solutions, several experimental tests have been performed. The focus was decided to be on structural behavior under in-plane loads, of 1.2 × 1.2 × 0.45 m historic masonry brick wall samples with lime-based mortar, with and without different strengthening interventions. Since the main objective of the study is to identify appropriate strengthening solutions that would lead to aesthetical rehabilitation of buildings while not ignoring their social context, the following interventions were considered: steel mesh reinforcement with standard lime-based matrix applied on one or two sides. Unreinforced specimens were also produced as a baseline for comparison. All strengthening interventions were placed on wall samples without structural damage in order to better understand the effect of the materials used. To validate the results, three different samples of each scenario were tested during the campaign. The tests are based on ASTM E519/E519M – 15.The results obtained for all the samples were subsequently evaluated and compared to understand their strengths and weaknesses, both from both structural and aesthetic point of view.

Dragos P. Bocan, Alexandra I. Keller, Marius Mosoarca, Catalina M. Bocan
Analysis of Lime Capping Mortars After Two Decades of Carbonating in Ambient Conditions or Exposed to Natural Weathering at Corfe Castle

In 1993, 13 lime-based mortar mixes were produced for trials at Corfe Castle, Dorset, UK [1, 2]. The trials aimed to evaluate mortars used for consolidating a section of the wall head at Corfe Castle. These mortars had to be resilient to weathering at the exposed location of the castle but remain sacrificial to the underlying historic stone. A sample of each binder and each mortar mix was also placed in sealed polythene bags and stored indoors under ambient conditions (unweathered). In 2019 (weathered) samples of each mortar mix were extracted from the mortar surface and 50 mm below the surface. This paper compares the unweathered and weathered samples for five mortar mixes that used Blue Lias lime putties with different hydraulicities, Unilit B Fluid X (Unilit) hydraulic lime, or Unilit and Chards non-hydraulic lime putty blends. Physical and chemical characterisation was conducted using thermogravimetric analysis (TGA), powder X-ray diffraction, optical imaging, and scanning electron microscopy (SEM) imaging with energy dispersive X-ray (EDX) analysis.These tests enabled a comparison between the hydraulicity and chemical composition of these mixes. TGA results demonstrated that binder choice and weathering conditions had no noticeable impact on carbonation after 26 years. Optical microscopy showed lichen growth on the weathered surface samples but not on the unweathered samples. SEM and EDX identified self-healing of cracks in weathered samples only. Moisture transfer, the ability to self-heal and acting as a barrier between lichen and stone are key features that enabled the mortars to protect the historic material.

Grace A. Morris, Kevin Briggs, Alison Henry, Richard J. Ball
Shear-Compression Test on Masonry Walls with an Innovative Experimental Setup

The behavior and failure mechanism of a masonry wall subject to in-plane shear depends on several factors, such as the wall geometry, the boundary conditions, the acting stresses, and the masonry mechanical parameters. The objective of this research was the study of the in-plane shear behavior of full-scale masonry panels through an innovative experimental setup, purposely designed to reproduce a double fixed boundary condition in order to induce a diagonal cracking failure mode. Such a boundary condition was ensured by the presence of an upper horizontal rigid steel beam, combined with the possibility of modulating the compressive load applied to the masonry panel, while increasing the horizontal displacement. Nonlinear numerical simulations were carried out to analyze the capability of the experimental setup of reproducing the desired loading and restraint conditions and to predict the shear behavior of a clay brick masonry panel. A finite element model was realized, in which all the components of the experimental setup were included to account for all possible failure modes, and the masonry panel was modelled according to a macro-modelling approach. The results of the numerical predictions were compared with the results of a shear-compression test on a masonry panel, which will be presented in the paper. The good agreement obtained between the numerical and the experimental results, both in terms of load vs displacement curve and development of the cracking process, confirmed the suitability of the setup in reproducing the assumed boundary conditions and shear failure mode.

Francesca Ferretti, Luca Pozza, Claudio Mazzotti
Mechanical Characterisation of Multi-Wythe Masonry Bridge in the City of Amsterdam

This paper presents the results of an experimental campaign carried out to characterise the mechanical properties of multi-wythe masonry infrastructure in the city of Amsterdam. Samples were extracted from a 1.2 m thick bridge’s pillar constructed in 1882. For the characterisation of shear and compressive properties of masonry, tests on cores with a 100 mm diameter were performed at the Stevinlaboratorium of Delft University of Technology. Samples were extracted along different locations in the wall thickness to evaluate the effect of exposure to environment conditions. Overall, the study provides a first insight on the mechanical properties of multi-wythe masonry city infrastructure and knowledge regarding the sampling and testing strategy for these structures. In turn, this will increase the knowledge on multi-wythe masonry, which is limited in literature, and will support the assessment of many infrastructures in typical Dutch canal cities.

Xi Li, Francesco Messali, Rita Esposito
NDT for Structural Diagnosis for Marble Columns. The Case of San Marco Basilica in Venice, Italy

Sonic tests are well-known non-destructive analysis technique (NDT). Independently or in combination with other examination techniques, they are widely used to understand and qualify structural elements and their mechanical properties, detect the presence of inner voids and flaws, and control the effectiveness of the structural consolidation.This paper presents the results of the combined analysis method, merging different NDTs such as visual inspection and sonic tomography mapping for columns in San Marco Basilica in Venice, Italy. The aim of the study was to assess the structural properties of these elements and to understand and locate the potential ongoing mechanical deterioration. Tomography maps were constructed in selected horizontal and vertical sections, for more profound study with three-dimensional analysis approach.The performed analysis confirmed the suspected mechanical deterioration in all studied stone elements. Most of the areas that exhibit low sound velocity, overlap with the highly deteriorated exterior zones previously identified though the visual surveys. The NDT approach allowed the identification of the types of structural deterioration, and their profound study in three-dimensional space.

Mila Cvetković, Salvatore Russo
Model Crystallization of Salts and Their Migration in Opuka Stone – The Local Historic Building Material of Prague Castle Area, Czech Republic

Processes associated with crystallization and salt migration in building materials are important factors contributing to material degradation and subsequent damage. Archaeological structures located in the area of Prague Castle, for which the presence of salts and frequent climatic fluctuations are typical, are particularly vulnerable to salt-related deterioration.As part of the monitoring and closer research of the archaeological excavations of Prague Castle, long-term measurements of temperature and humidity were carried out in locations across the site. This data collection provided information on the effect of climatic cycles, including temperature and relative humidity changes, in the building materials. It was confirmed that the local opuka stone is highly susceptible to salt contamination and damage. The climate fluctuations cause critical conditions for dissolution and subsequent crystallization thresholds of the salts are regularly exceeded. This confirmed the significant impact of these cyclic changes in this archaeological area.In conjunction with data obtained from measurements of climatic cycles and opuka stone properties from the Third Courtyard of Prague Castle, a laboratory-based experiment was designed. The aim was to observe the crystallization and migration of salt in specimens of opuka stone. Stone specimens were immersed in sodium sulphate solution and exposed to specific climatic conditions (20 ℃ and 80, 70, 50 and 40% RH) that led to salt crystallization. The behaviour of salt was also studied under conditions where water vapor passes through the specimens. This experiment enabled the determination of the risk of damage as a function of salt crystallization in the opuka stone.

Petr Kozlovcev, Emily C. Painter, Kristýna Kotková, Jan Válek, Jana Maříková-Kubková
Commentary on the Flat-Jack Test – Factors Influencing the Measurements

The paper presents the results of several flat-jack tests conducted on large sections of brick walls prepared in a laboratory. The influence of two basic factors was studied – the shape of the flat-jacks and distance between them – on the magnitude of the recorded strains. The three most common flat-jack shapes (semi-circle, rounded-rectangle and rectangle) were used for that purpose. The aforementioned spacing adopted for the purpose of the test was 3, 5 and 7 layers of bricks forming the analyzed brick wall specimen. Both of these factors have a significant impact on the boundary conditions of the test and the recorded results. For the purpose of comparison, brick prisms of a height corresponding to the spacing of the flat-jacks were cut out of the tested walls. The entire walls and then the cut out prisms were subjected to a load with a compressive force in order to estimate the modulus of elasticity E of the brick wall. Comparison of the values obtained shows that the semi-circle flat-jacks widely used in engineering practice might overestimate the rigidity of the wall tested. The reason seems to be the small surface area of this type of flat-jack and insufficient depth of its placement inside the wall bed joint. Only rounded-rectangle and rectangle flat-jacks allowed for estimating results that were more similar to those recorded in the other tests on masonry. Double flat-jacks testing allows for a minor-destructive assessment of the deformation parameters of the outer layer of brick wall. The recorded values were comparable with the results obtained by other authors.

Dawid Łątka
First Step Toward Preservation of Ancient Toprak Qala in Uzbekistan: Estimation of Erosion and Deterioration Rates by Laser Scanning

There are a few castles in Northern Uzbekistan that are constructed from untreated earth material. One of the most famous ones is the Toprak Qala near Urgench, Uzbekistan. It is dated to be from the 2nd – 3rd centuries and used to be one of the forts on the northern branch of the Great Silk Road, a trading route between Europe and China. It is located right at the edge of the Kyzyl-Kum Desert. Since it is constructed from untreated earth material, it has deteriorated over time. This process was accelerated by the failure of the original drainage system, which caused rainwater to remain trapped inside the monument. The main objective of this paper is to evaluate its current condition and identify the “hot” spots of the monument which require immediate attention. The objective is achieved by conducting a laser scanning expedition to capture the monument’s current condition by means of a terrestrial laser scanner. The monument was scanned from more than 20 different stations. All of them were stitched into a single point cloud that reflects its current condition in a 3D rendering with a few millimeters accuracy. Essentially, a digital twin of the current state of the monument was created. The laser scanning was conducted in the summer of 2022. A follow-up expedition is scheduled for the summer of 2023 to quantify the rate of deterioration over one year. This paper provides examples of detailed analysis of the current condition, the results of which will be utilized in future comparative studies of two laser scans separated by a year. A summary of the major findings of the project is provided.

Shakhzod Takhirov, Bakhodir S. Rakhmonov, Ravshanbek Nafasov, Abbos Samandarov, Sevara Sultanova, Mirzokhid M. Akhmedov, Ravshan A. Shamansurov
Measurement of Solid Brick Compressive Strength and Anisotropy on Non-standard Small Cubic Specimens

An experimental research has been carried out on the possibility of measuring the compressive strength of ceramic solid bricks by testing in laboratory non-standardized cubic samples measuring 40 × 40 × 40 mm3. The viability of such approach has been confirmed through a systematic comparison, for a variety of brick types, with compression strength values obtained for the standard prismatic 100 × 100 × 40 mm3 specimen. The comparison has allowed the derivation of a reliable correlation to estimate an equivalent compressive strength based on the 40 × 40 × 40 mm3 specimen. The proposed cubic specimen is largely advantageous in the characterization of the compressive strength of existing masonries built with moderately thin bricks (with thickness in the order or 4 or 5 cm). It can be also used to accurately characterize the anisotropy that the manufacturing process can induce in the bricks and its influence on the strength. Taking advantage of this possibility, the paper also presents a detailed investigation on the anisotropy of different brick types.

Albert Cabané, Luca Pelà, Pere Roca
Reinforced Interfaces Between Drums in Ancient Columns

The current paper presents part of the content of a research program, aiming at investigating the effect of interfaces, reinforced using vertical connectors (gomfoi) on the seismic behaviour of ancient monuments, and more precisely on the seismic behaviour of columns and colonnades, where the interfaces between drums are crossed by shear connectors.The ancient Monuments are constructed following the dry construction system, i.e., structural members (of porous stones or marble) with large dimensions are positioned without mortar. This is typical for columns as well. In addition to the perfect contact along the interfaces of consecutive stones, iron or timber connectors of various geometries are frequently used both in horizontal and vertical members.Two distinct types of vertical connectors are identified in ancient constructions, namely, the system of “poloi-empolia” (of cylindrical shape) and the “gomfoi” (of orthogonal parallelepiped shape). Even though gomfoi are known to connect mainly stone blocks composing horizontal members (beams and wall blocks), in case of monuments constructed in the Hellenistic Era, vertical connectors are used also between the drums of columns, in an arrangement suggesting that it was intended to improve the behaviour of the columns against seismic actions in any direction.In this paper, the documentation of the characteristics of vertical connectors-gomfoi in ancient columns is presented, together with a literature review of the available experimental and analytical works. The data, together with preliminary analysis, are necessary for decisions to be made related to the shake table tests that will follow.

Vasiliki Palieraki, Eleni Tavouktsi, Constantinos Arvanitis, Eleni Karakike
Documentation and Experimental Behaviour of Vertical Connectors in Ancient Monuments Under Cyclic Actions

Ancient monuments are constructed following the dry construction system. Large dimension structural members (stones) are placed without mortar, while perfect contact along their interfaces is ensured. In addition, iron or timber connectors of various geometries are used both in horizontal and vertical members.Three types of connections are identified, namely, the system of “polos-empolion”, placed (vertically) in columns, the horizontal connectors (clamps), and the vertical connectors (gomfoi), used in structural parts such as cella walls. The connectors do not contribute to the transfer of static loads, but they are activated when relative displacements are imposed to the structural components, e.g., in case of earthquakes.The paper focuses on vertical connectors, crossing the interfaces between successive courses of stones, and investigates their behaviour under seismic conditions. Vertical connectors are usually made of iron, and they are positioned in grooves chiselled in the structural members. The space between the walls of the groove and the connector is filled with melted lead.Documentation of vertical connections in ancient Greek monuments is presented, namely, their topology, and dimensions, and the typical pathology of both connectors and connected members. Several monuments are studied through literature survey and in situ observation.This documentation has assisted the design of the experimental campaign. Its purpose is to investigate connections between marble members, simulating the typical original ones, crossed by iron connectors. The testing of full-scale specimens has confirmed the pathology surveyed in situ, thus, proving the function of the vertical connectors in ancient monuments.

Eleni Tavouktsi, Vasiliki Palieraki, Elizabeth Vintzileou
Assessment of Wood Degradation Produced by Insects in Order to Quantify the Loss of Mechanical Strength of Load-Bearing Elements

Biological degradation due to insects is very frequent on load-bearing wooden elements in historic buildings. Degraded areas are usually excluded from the resistant section, although they may still make a mechanical contribution to the structure. An assessment of the depth and degradation level of the insect attack is therefore crucial for a better knowledge of the residual strength of the wooden elements.Specimens degraded by insect were evaluated in terms of percentage of surface occupied by bores, a procedure that an expert operator could apply easily during the on-site assessment. Following, resistance drilling measurements and destructive mechanical tests were performed to determine density, compression, shear and bending strength and bending modulus of elasticity.The results showed moderate but strongly significant negative correlations between the degradation level and the mechanical properties. On the contrary, density was unrelated, as well as drilling resistance. The latter, however, correlated strongly with density and mechanical properties, and, combined with the visual assessment of degradation, made the mechanical property prediction as effective as for sound wood.

Michele Brunetti, Giovanni Aminti, Benedetto Pizzo, Michela Nocetti
Digital Techniques for the Documentation, Diagnosis, and Safety Assessment of Architectural Heritage

Heritage conservation strongly relies on in-depth knowledge of the cultural asset to preserve its values. In this regard, the survey-based phase of documentation is needed for a complete understanding of the morphological characteristics of the construction and its context, in order both to reveal situations that possibly affect the structural safety, and to implement the actual deformed geometry into a FE model. In the last decades, researchers have devoted great attention to the application of architectural heritage safeguarding methodologies that involve new forms of digital products resulting from the progress of advanced survey techniques in the field of digital representation of heritage structures. 3D models by themselves have the great advantage of providing a complete and metrically correct representation of the building. Besides, when informed by applying computer-based cognitive and interactive tools, they become useful digital products for investigations related to shape and damage phenomena. This work explores the capability of traditional survey techniques, and innovative, cost-effective ones for the documentation, diagnosis, and monitoring of heritage structures. The presentation of case studies introduces the application of adequate knowledge practices aimed at triggering a process of safeguarding cultural heritage structures.

Giada Bartolini, Anna De Falco, Francesca Giuliani, Massimiliano Martino
An Update of Sonic Pulse Velocity Tests on Heritage Buildings: Correlation with Masonry Types

The preservation of the architectural heritage passes through a ‘knowledge process’, based on inspections and diagnostic procedures. In this context, the Sonic Pulse Velocity Test (SPVT) is a viable option among non-destructive tests as it aims at evaluating the quality of masonry walls through the transmission of elastic waves. Wave velocity qualifies the density of the tested material: the more compact it is, the faster the waves propagate, although the acquired data cannot be considered as an estimate of mechanical parameters.In this paper, a database of 286 direct SPVTs is presented; the tests were conducted in the last twelve years on 50 buildings (mainly cultural heritage buildings). The direct configuration was adopted for the tests, thus evaluating the consistency of a wall cross-section. The average sonic velocity was calculated for each test; the results were grouped as a function of the masonry type, as described by the Italian building code, to define a range of velocities which qualify a type. A total of 5 masonry textures were recognized.The data were also grouped according to the building type, to explore the quality of construction, and the geographic area to evaluate a possible correlation between the SPVT results and local building traditions. Finally, for 37 masonry panels, the effectiveness of grout injections was evaluated by defining the velocity improvement after the intervention.At last, to validate the masonry qualification obtained from the SPVTs, a correlation between sonic velocities and the mechanical parameters obtained from flat jack tests carried out on the same sampling area for 51 panels was explored.

Ylenia Saretta, Filippo Casarin, Maria Rosa Valluzzi
In-Situ Vibration Tests of Timber Frame Structures with Knee Braces

Although the natural period of vibration is a key parameter in wind and seismic engineering, it can be challenging to determine the period of vibration for traditional timber frames because there is a lack of guidance in design standards compared to other structural systems, and because it can be difficult to employ conventional measuring techniques. In this paper, a non-destructive in-situ vibration test method is presented to better understand the natural period of vibration of traditional timber frames with knee braces. A low-cost measuring technique was developed by installing an app on a smartphone to measure accelerations, placing the smartphone on the spandrel beams of the timber frame in the field, and then vibrating the frame in the principal directions using a hammer or mallet. The single-sided amplitude Fourier spectrum of the data was used to determine the period of vibration. Twelve free-standing traditional timber frames with knee braces were tested at various sites in the United States. The results indicate that the in-situ period of vibration was lower compared to an empirical estimate of the period of vibration based on ASCE 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures that is commonly used in the United States for other structural systems. The findings also suggest that the test method developed in this study may be an efficient approach for structural analysis of smaller-sized historical timber frame structures.

Zachary Halisky, Johnn Judd
Dynamic Identification and Damage Detection for a Greco-roman Monument

Dynamic identification is the process of the development of mathematical models for a system based on the vibration response. We considered a complex monumental building damaged by the 2015 Gorkha earthquake for system identification using ambient vibration records taken after the earthquake. The operational modal analysis technique implemented was carried out using Numerical Algorithm for Subspace State Space System Identification (N4SID). Ambient vibration records were taken in seven locations of the 113.26 × 85.27 m and 16.7 m tall monument initially constructed in 1910. The results of system identification highlighted that the first mode natural frequencies varied between 1.63–4.37 Hz for the seven setups, whereas the dominant vibration always occurred parallel to the short wall direction. The variation within a wing likely indicates the localized damage that was not morphologically identified. For a complex construction system such as Greco-Roman monuments without construction details, several sets of measurements are found to be more informative in terms of preliminary damage detection. We compared the results of system identification with the codal provisions to estimate vibration frequencies and found that the codal formulas give rise to a highly unrepresentative first mode frequency.

Dipendra Gautam, Rabindra Adhikari, Ashim Niraula, Simon Olafsson, Rajesh Rupakhety
Structural Behaviour of Masonry Newly Concept Vault Through Tilting Table Testing on a Scaled Model

Masonry vaults represent one of the most recurrent types of horizontal structural elements in architecture in European countries, even in areas characterized by a high level of seismicity. Therefore, the evaluation of their structural safety and their mechanical behaviour remains of primary importance. This paper proposes to apply already consolidated structural analysis methodologies on a contemporary vaulted space. The aim, therefore, is to investigate the dynamic behaviour of a newly concept vault generated starting from the “Flat vault of Abeille” patented in 1699. The reinterpretation of this vault and its use would allow both to enhance the existing Architectural Heritage and to characterize the realization of new buildings using traditional construction materials and techniques, without going against the canons and guidelines of architectural restoration. It follows that the identification of this “new type” of vault is essential to design it correctly and to optimize the geometry for structural purposes.The present paper describes the results of an experimental campaign about tilting table tests on a 1:8 small scaled vault and and the numerical simulation of the model through the Distinct Element Method (DEM). The physical model is coherent with the numerical one because it has been realized with 3D printed blocks assembled with dry joints. The seismic behaviour of the vault was experimentally studied through quasi-static tests by means of a tilting table to evaluate the collapse angle and the Horizontal load Multipliers for different in-plane angles in order to define a resistance domain of the vault.

M. F. Sabbà, G. Frappa, G. Fallacara, D. Foti
Concrete Durability Tests to Evaluate the State of Heritage Buildings and Existing Constructions in a Semi-arid and Highly Seismic Region of Argentina

Nowadays there are various durability tests for concrete to evaluating the state of conservation of heritage structures and other important existing constructions. Non-destructive tests can be applied directly in situ, and others are carried out in the laboratory through the extracted samples. In this work, concretes made from the beginning of the 20th century to the present with local materials are evaluated.The Mendoza City and the surroundings area (Greater Mendoza) is considered the urban conglomerate with the highest seismic risk in Argentina due to the geological phenomenon of near-fault. Local seismic history has shown the fragility of adobe masonry constructions, considered as an unlawful material in the region. Due to, the use of concrete has been promoted in the confined masonry, obtained with very poor technology and the quality that does not exceed 20 MPa of compressive strength, except in some industrial constructions.The tests carried out in situ correspond to the measurement of air permeability, impact resistance by means of a sclerometer and carbonation, and the laboratory tests on concrete cores for determining compressive strength. The interpretation of the results allows us to guide about of the quality of studied concrete and to correlate it with the damage found due to the effect of earthquakes and reinforcement corrosion in the case of reinforced concrete from the beginning of the 20th century and iron reinforced masonry found in different historical constructions of the Greater Mendoza.

Domizio María, Maldonado Noemí, Fernández Luco Luis, Martín Pablo, González del Solar Gerardo
Comparison Between the Mechanical Properties Obtained from Constructed Masonry Prisms and Masonry Prisms Extracted Directly from Structures

The comparison of the values of mechanical properties of stone masonry obtained through experimental tests of two types of the masonry prisms with aspect ratio 1:2 is presented. The first ones were built using materials similar to those used in the construction of a 1:8 scale model of a typical colonial temple, trying to reproduce the same stone-mortar ratio used; while the second ones were directly extracted from this model with a diamond chain saw keeping the same aspect ratio. The specimens were tested following the same test methods. According to the results, the values of the masonry density were similar in both cases, but the compressive strength of the extracted masonry prism was two times greater than the values obtained from built masonry prism. The variation of the Young´s module of the built masonry prism was between 9 to 33% of the value obtained from the extracted masonry prism.

Marcos M. Chávez, Fernando Peña
The Determination of Compressive Strength of Masonry Elements of Monuments by the NDT Methods

Nowadays, the compressive strength of masonry elements is usually determined non-destructively using a rebound hammer Schmidt LB. However, the production of Schmid LB is going to be discontinued soon. The determination of the compressive strength of the masonry elements will become very challenging discipline. Therefore, this work aims to improve the way of assessing the compressive strength of masonry elements with minimal damage to the historic structures. In this paper, the application of alternative methods of determining the compressive strength of masonry elements are verified. This strength is determined by two ways. The rebound hammer Silver Schmidt in versions L, N and L with mushroom plunger, which is designed for control of strength of concrete for formwork removal, were used. The second way is the modified drill, which TZÚS Prague presented in 2020 in a new modification KV-3. The regression (calibration) curves are deduced for both methods in this paper. The regression (calibration) curves were determined on a large set of historic solid fired bricks so that the full spectrum of strengths was represented. The masonry elements were firstly tested non-destructively and then the elements were subjected to destructive measurements.

Vojtěch Bartoň, Petr Cikrle, Jaroslav Šnédar
Research on the Effects of Structural Characteristics on the Mechanical Performance of Zhutou Puzuo in Yingxian Wooden Pagoda

The Zhutou Puzuo joint is an important component of the Yingxian wooden Pagoda. Study on Puzuo’s seismic performance for the protection of the Yingxian wooden pagoda is of considerable practical importance. The impact of structural characteristics on the seismic performance of the Zhutou Puzuo is the focus of this paper. The Zhutou Puzuo models at 3rd to 5th storey open-layer outer floor are tested by quasi-static cyclic test. Results show that the more the number of Pu of the models with varied structural characteristics are, the stronger the energy dissipation capacity and the greater the horizontal bearing capacity are. In positive loading, rotational deformation is the predominated deformation in the Zhutou Puzuo, while both rotational and slip deformation predominate in negative direction. The proportion of slip deformation of components decrease with the increasing the number of Pu. In the negative loading, the proportion of slip deformation increases when the number of Pu decreases. However, negative slip deformation increases dramatically when the ears of Sandou or Qixindou between two adjacent layers are sheared. The maximum proportions of slip deformation of DG-1, DG-2 and DG-3 accounts for 51%, 47% and 87% respectively. The sliding components of the Zhutou Puzuos at 3rd to 5th story are primarily located in the middle and upper portions of the model. The research can give a solid basis for the safety and rehabilitation of the Yingxian wooden pagodas.

Lin-lin Xie, Wen-yi Yang, Jun-xiao He, Yong-hui Jiang, Xiang-jin Wang
Experimental Study of Seismic Performance of Zhutou Puzuo with ‘Ang’ Under Different Vertical Loads

Study of seismic behavior of Zhutou Puzuo with ‘Ang’ lays critical foundations for understanding the seismic performance of Yingxian Wood Pagoda. To explore deforming behavior and seismic performance of Puzuo with ‘Ang’, two scaled models derived from Yingxian Wood Pagoda at 1:3.7 were designed and manufactured. Low cyclic-reversed loading experiments under different vertical loads were carried out. Based on the analysis of hysteretic curve, skeleton curve and equivalent viscous damping coefficient, it was found out that the effects on the above relevant index and deforming behaviors of different loads as following: Increasing vertical load hardly changed deformation features of this kind of Puzuo, but it resulted in much more asymmetric performance in hysteretic curve and remarkable improvement on all of Puzuo’s relative properties. In detail, the increasement of 3.7 times of vertical load enlarged load-carrying capacity under both of positive and negative direction, initial stiffness and consumption of energy at times of 2.2, 2.9, 2.4 and 3.0 respectively. In addition, raising vertical load changed the position where the initial slip occurred at early stage of test. But it changed neither mode of accumulating slip nor the weaken positions. However, the Puzuo’s finial slip pattern remained similar, which it mainly performed as slipping between the First Huagong and Second Huagong. The relevant research results offered reference about studying on seismic performance of Yingxian Wood Pagoda.

Jun-xiao He, Wen-yi Yang, Lin-lin Xie, Yong-hui Jiang, Xiang-jin Wang
Experimental and Numerical Studies on the Bell Tower of the Transfiguration Basilica on Mount Tabor, Israel

The Church of the Transfiguration is a Catholic Basilica located on top of Mount Tabor in Galilee, Israel. It was built in 1924 following the design of the Italian architect Antonio Barluzzi on the ruins of an ancient Byzantine church (4th-6th century) and of a Crusader church (12th century).The façade of the church is characterised by two twin towers, connected by an arch supported by two columns. Bells are located only inside the South Tower. An extended crack pattern affected the Bell Tower, caused by the dynamic actions of the bells, transferred through the existing steel bellframe rigidly connected to stone masonry walls.A Finite Element Model of the Bell Tower has been implemented in order to evaluate its structural behaviour and dynamic response to static and dynamic loading. The model has been calibrated using a dynamic identification test, to identify the main frequencies of the tower, considering its particular external restraint conditions, due to the presence of the church in the North-East corner and of the arch in the North-West corner.The study allowed the design of the new steel bell frame, which has been equipped with damped support, in order to reduce the forces transferred to the masonry walls by the bells’ movement. The stiffness of the damped supports has been carefully investigated to avoid resonance phenomena with the natural frequencies of the tower.After the completion of the restoration works and of the mounting of the new bell frame, a new dynamic test has been carried out in order to confirm the numerical model design results.

Sonia Bellin, Marco Mocellini, Filippo Casarin, Fabio P. Marchesini, Vincenzo Zuppardo, Leonardo Di Marco
Dynamic Identification of Large Thin Shell Structures in Concrete

The paper presents the results of a recent testing campaign carried out on the vaulted structures built by Pier Luigi Nervi in Torino Esposizioni. Nervi’s halls are a spatial structure masterpiece, admired for their daring and innovative conception. The technological achievements of the 20th century have allowed conceiving unprecedented large scale and complex structures. However, the experimental nature of numerous innovative structural and spatial configurations adopted by the designers of the time have revealed over time intrinsic fragilities that, when neglected, have threatened their long-term structural integrity.In addition, 20th century’s structures were usually conceived without accounting for seismic actions, but only for static configurations, in accordance with the technical standards of the time. Therefore, it is of crucial importance to assess the dynamic behavior of these structures to understand their vulnerability and plan their correct preservation measures.Due to its complex configuration, the setup of dynamic testing campaign for Hall B built by Nervi presented many challenges, including: i) the complex optimization problems due to the spatial characters of the vaulted structure; ii) the possible effects of damage degradation or anomalies.The aims of this investigation were to investigate the behavior of historical spatial structures to seismic actions; and to detect the presence of possible structural anomalies.

Erica Lenticchia, Gaetano Miraglia, Rosario Ceravolo
Experimental Durability Analysis of Historical Ferrocement

The paper presents the results of a recent testing campaign carried out on the ferrocement elements built by Pier Luigi Nervi in the structures of Torino Esposizioni. These pavilions, built between 1947–1953, allowed Nervi to apply for the first time in a large structure his advances in the use of ferrocement in civil construction that he had pioneered during the war. The results obtained by Nervi were patented immediately after the end of the construction site and would have characterized Nervi’s technique for his whole career. Before Nervi’s civil applications, ferrocement was mainly used to build boats. The material is characterized by the multiple layers of mesh or fine rods completely impregnated with cement mortar, which Nervi noted could be applied to build slabs and roofing elements by using a very low amount of material. Considering the historical value of the structures and since the ferrocement elements are extremely thin, to investigate the durability of this material, small-scale ferrocement mockups were built in the laboratory, starting from a small sample collected on-site.A detailed testing program was developed, which included applying different treatments to the specimens before subjecting the samples to an accelerated weathering procedure to test the effects of each (mixed-in corrosion inhibitor, surface-applied inhibitor, etc.). The analysis of the ferrocement developed by Nervi in his constructions is a mandatory step for evaluating the health state of these elements and will help define the guidelines for their conservation. Moreover, it will help to expand the knowledge of Nervi’s system.

R. Ceravolo, E. Lenticchia, I. Matteini, G. Sorrentino, F. Tondolo
Large-Scale Experimental Investigation of Sustainable, Low-Cost Seismic Isolators Based on Rolling Rubber Spheres

This study presents the results of a large-scale experimental investigation of sustainable and low-cost seismic isolators based on deformable rubber spheres rolling on concrete surfaces. A potential application of the isolators could be in low-rise masonry structures in the developing world. Parameters of investigation were the type of rolling spheres, the geometry of the concrete surfaces, and the weight that each isolator supports.Initially, the compressive response of the isolators was examined. Subsequently, lateral cyclic tests were performed. Finally, 1170 shake-table tests were performed in 1:2 scale, with various different isolators subjected to a large number of ground motion excitations.Results showed that the compressive strength of the spheres was substantially higher than the design load. The non-negligible deformability of the spheres leads to a lateral cyclic response that is different from the one of a rigid body model. The rolling friction coefficient ranged between 3.7% and 7.1%. During the shake table tests, the isolators reduced the acceleration transmitted to the superstructure (to 0.15 g) while maintaining reasonable peak and zero residual displacements. The shake table tests were repeatable, and the isolators did not deteriorate even after subjected to 65 ground motion excitations.

Antonios A. Katsamakas, Michalis F. Vassiliou
Vibration Isolation Capabilities of a Low-Cost Seismic Isolation System Based on Elastomeric Rolling Spheres for Masonry Structures

In recent years, seismic isolation has been used as an effective retrofit technique to protect historical buildings and structures against earthquakes. However, for some isolation devices, man-induced low-amplitude vibrations (e.g., construction activities, vehicle, and rail traffic) can still be directly transmitted to the structure. These vibrations can cause damage and deteriorate structural elements if they persist during extended periods of time, especially on masonry or unreinforced structures. This paper explores the horizontal low-amplitude vibration isolation capabilities of a low-cost seismic isolation system based on elastomeric rolling spheres for low-rise structures. The isolation system consists of elastomeric spheres placed underneath the structure, providing lateral isolation through rolling and still providing vertical flexibility and damping through the deformability of the spheres. Experimental tests were performed to characterize the sphere’s rolling mechanical behavior under relatively small deformation amplitudes, calibrating a simple yet effective nonlinear model to perform further numerical analyses under other inputs that the shake table could not reproduce. The vibration isolation performance of the spheres was addressed through its transfer function. The results showed that the proposed isolation system based on rolling elastomeric spheres has the potential to serve as a dual isolation system, i.e., protect the structure against earthquake events and long-term ambient vibrations. Further experimental tests need to be performed to validate the conclusions presented herein and extend the applicability of such isolation system to industrial machinery or sensitive equipment where traditional vibration isolators are required but do not protect against earthquakes.

Sergio I. Reyes, Antonios A. Katsamakas, Michalis F. Vassiliou
Mechanical Behavior of Brickwork Multi-ring Masonry Arch Bridges Constructed with Different Bond Types

The aim of this paper is to assess the mechanical behavior of brickwork multi-ring masonry arch bridges constructed with different bond types. Based on the Discrete Element Method (DEM), a series of two-dimensional numerical models of masonry arch bridges were developed and validated against experimental results obtained from the literature. A parametric analysis was then performed to investigate the effect of: (a) multi-ring arch barrel; (b) backfill properties; and (c) bond properties of mortar joints on the failure mechanism and load-carrying capacity (Ul) of masonry arch bridges. The results demonstrated that an increase in the elastic modulus of the backfill material decreased the deformability of the soil, which further limited the deformation of the arch barrel and led to a reduced Ul. Nevertheless, the effect of Poisson’s ratio of backfill material was found to be insignificant. However, the thickness of the arch barrel considerably affected the Ul of the masonry arch bridge. In particular, an increase of the arch thickness led to an exponential increase of the Ul. Among the parameters investigated in the parametric analysis, the bond strength of the unit-to-mortar interface had the most significant influence on the ultimate strength of masonry arch bridges. Moreover, both the four-hinge and ring-separation failure mechanisms were captured by the numerical model. The results presented in the study can be used towards assisting the understanding of the soil-structure interaction and failure mechanisms that occur in brickwork masonry arch bridges.

Bowen Liu, Vasilis Sarhosis, Zhenyi Yan
Reducing Uncertainties in Response Predictions of Earthquake-Damaged Masonry Buildings Using Data from Image-Based Inspection

Image information about the state of a building after an earthquake, which can be collected without endangering the post-earthquake reconnaissance activities, can be used to reduce uncertainties in response predictions for future seismic events. This paper investigates the impact of using data from image-based inspection of building facades on reducing the uncertainty in predictions of demand parameters that are useful for seismic assessment and retrofitting. Data consist of observable cracks in masonry walls. Experimental data from shear-compression tests conducted on masonry walls is used to define a criterion that associates the demands on the walls to the onset of observable shear cracking to use it then during the analysis of a complete building. The procedure is validated using experimental data from a shake-table test conducted on a half-scale building with unreinforced masonry elements for which, based on an equivalent frame model approach, nonlinear dynamic simulations are performed on a set of model instances of the building. A model falsification methodology is used to discard models for which the simulated response does not match the observed behavior, thus leading to a reduced model set with which the uncertainties in response predictions are reduced. Compared to when no data related to the damaged state of the building is used, the number of models is significantly lowered when the damage recognized in the building is used as a criterion for falsification. Furthermore, models that are not falsified provide accurate predictions for maximum roof displacements, maximum base shear, and the ability to predict the activation of several failure mechanisms, such as out-of-plane failure and toe crushing in the masonry walls, showing that detection of shear crack patterns is a powerful falsification criterion.

Mathias Haindl, Bryan Pantoja-Rosero, Katrin Beyer, Ian F. C. Smith
Peak Displacement Response Induced by Bell-Swinging on the Masonry Tower in Castel San Pietro Terme, Bologna

The dynamic identification of masonry bell towers has been deeply investigated in the literature, mainly targeting the effect of seismic actions on the structures. However, new research horizons are still to be widened in terms of the interaction between the bell-swinging system and the structure itself, and specifically in terms of simplified experimentally-based methods that can be adopted by practitioners for the structural assessment and possible strengthening interventions on such towers. Indeed, the motion and the excitation forces, generated by the activation of the tower carillon, are often responsible for resonance phenomena causing high amplitude dynamic vibrations in slender structures which may trigger the development of structural vulnerabilities. This paper analyses the data collected during an experimental campaign investigating the effect of different bell-loading conditions on the historical masonry bell tower in Castel San Pietro (Bologna, Italy). The research proposes an original simplified method to take into account the dynamic response of the structure by extracting, from the displacement time histories, equivalent static displacement fields to be implemented inside a manually calibrated finite element model. The results show useful indications for the design of strengthening interventions.

Emma Ghini, Matteo Marra, Michele Palermo, Giada Gasparini, Stefano Silvestri, Riccardo Mario Azzara
Degradation of Historical Façades Exposed to Wind-Driven Rain: Laboratory Simulation and Protective Measures

Wind-driven rain constitutes one of the most significant sources of moisture in buildings [1, 2]. Specific research evidence concerning the influence of wind-driven rain penetration on the durability of historic materials and on the degradation of decorated surfaces, still needs to be comprehensively investigated and fully evaluated. This paper outlines the results from an experimental investigation carried in the climatic wind tunnel. It is composed of three main parts: (1) field-work consisting in a detailed survey of damage to decorated, historical façades; (2) laboratory work concerning the simulation of wind-driven rain, its assessment and validation through comparison to natural weather data; (3) experimental evaluation of protective panels as a temporary protective measure for façades with heritage values. The rain simulation data show good correlation with the Dingle and Lee model [3] while slightly diverging from the raindrop size distribution provided by Best [4] due to the inability of the sprinkler system to generate larger drop sizes for high pressures and the side walls effect in the tunnel. The experimental analysis shows that protective panels consisting of single-ply plastic net with 1x1cm grid fixed to a timber frame, provide a simple and cheap solution for the partial protection of the façades from wind-driven rain. Such panels provide good visibility, water permeability (avoiding wind blocking effects) and at the same time adequate catching of raindrops in order to reduce degradation of the historical façades beneath them. Future work is suggested in order to deepen experimental validation of rain simulation and to evaluate the protective panels in re-al life applications.

Riccardo Cacciotti, Arsenii Trush, Stanislav Pospíšil, Karel Pitaš, Ondřej Fišer
The Inspection by Minor Destructive Testing in Projects of Adaptive Reuse of Historical Masonry Buildings and Design of Green Rooftops in Barcelona

The mechanical characterisation of existing masonry in historical structures encounters several technical difficulties due to the complexity and heterogeneity of this traditional material, as well as to the need for respectful inspection activities able to preserve the cultural heritage value of the building. This paper presents and discusses different Minor Destructive Testing (MDT) techniques oriented at estimating, either in-situ or in the laboratory, the mechanical properties of masonry at the level of components, such as units, tiles, and mortar joints, and at the level of the composite material. The research addresses different issues related to the execution of laboratory tests on sampled historical materials, such as selection of the size and shape of specimens, different types of treatments for the sample, testing protocols, and experimental setup. The complementary use of Finite Element Method (FEM) models represents a valuable activity to provide a good understanding of the experimental behaviour exhibited by the specimens, and especially concerning the execution of non-standard laboratory tests. The possibility of in-situ MDT is explored considering techniques based on different portable instruments, previously calibrated through ad-hoc experimental programs under controlled laboratory conditions. The research is based on a high number of tests executed at the UPC within the context of several experimental programs linked to projects of adaptive reuse of existing masonry buildings and design of green rooftops in Barcelona.

Luca Pelà, Albert Cabané, Emerson Cuadros, Larisa García-Ramonda, Pere Roca

Seismic Analysis and Retrofit

Retrofitting of Historic Watchtower in Abu Dhabi, UAE

The historic fort of Qasr Al Hosn is a landmark at the heart of the modern city of Abu Dhabi, UAE. It includes the city’s oldest permanent structure, a coral and sea stone watchtower built to protect the settlement of Abu Dhabi first established on the island in the 1760s. The tower forms the only surviving part of a square fort, constructed around 1800 CE as the stronghold and seat of government of the ruling Āl Nahayyān family. Qasr Al Hosn was enlarged by Shaikh Shakhbūt Bin Sultān Āl Nahayyān in the 1940s and extensively restored in the 1980s. In light of its historic importance, Qasr Al Hosn underwent an extensive conservation and retrofitting campaign, starting in 2013, which concluded with the reopening to the public in December 2018.This paper deals with the development of the conservation strategy for the Old Watchtower: the intervention aimed both to remedy damage and to improve the structural performance of the tower without further affecting the original materials.The inner r.c. lining that had been built in the 1980s and that was deemed the main culprit for the damage to the historic stonework was removed in stages; careful repair and strengthening of the masonry fabric was carried out, using traditional materials and techniques. Additionally, basalt fibres were bonded in the outer plaster layers so as to enhance the seismic response of the structure and comply with current code prescriptions regarding structural safety.The paper details the survey, design process and implementation of the strengthening measures as well as a recent maintenance intervention, which targeted the detachment of the plaster and fibre strips. This latest intervention prompts a number of considerations on improvements and changes that should be considered in future interventions.

S. Paganoni, F. Othman, A. Chabbi, A. Aqeel, P. Sheehan, C. Ziegert, M. Khalifa
Modelling of Damage in Historical Masonry Façades Subjected to a Combination of Ground Settlement and Vibrations

Historical masonry façades are sensitive to various damaging processes. A recent study, looking at the initiation and progression of cracks in masonry, in the range of 0.1 to 5 mm in width and thus corresponding to light damage [1], has allowed for the calibration of finite-element models that include a material model capable of accurately replicating this damage and which is populated with material properties corresponding to existing structures [6]. The models, which also include a soil-structure interaction boundary designed to account for the effect of the soil during earthquake vibrations [7], have been used to determine the fragility of masonry buildings via the proxy of 2D walls [2]. In the study presented herein, the finite element models are employed to replicate the geometry of (historical) masonry facades to determine their sensitivity to light damage as a consequence of the two damaging processes observed to be most common for this type of façade, namely (differential) settlements and (earthquake) vibrations [3].The masonry façades were first pre-damaged via settlement distortions which generate just-visible cracks in the order of 0.1 mm to 1 mm in width. Then, an acceleration time history corresponding to two different Dutch earthquake events and two recordings of traffic-induced building vibrations [9] were separately applied at the base of the models. In this manner, the effect of existing damage could be assessed in regards to the aggravation generated by vibrations. The settlement part of the study revealed that long façades were more vulnerable to applied soil distortions, for instance. Then, subsequent vibrations further increased damage for intensities measured with a peak ground velocity (PGV) larger than 2 mm/s while the control set of virgin or uncracked façades remained undamaged at this PGV. At 32 mm/s, many pre-damaged façades also exceeded the light damage range. At equal PGV, the traffic vibrations, with a larger number of effective cycles, resulted in increased damage aggravation in comparison to the earthquake recordings.

Paul A. Korswagen, Michele Longo, Alfonso Prosperi, Jan G. Rots, Karel C. Terwel
Seismic Analysis of Zagreb Cathedral - Current State

The neo-Gothic cathedral in Zagreb, the largest Croatian sacral building, was severely damaged by the 5.4 magnitude earthquake on March 22, 2020. Three years after the main seismic event, aftershocks are still causing displacements on the stone blocks of the towers. The assessment of the current condition of the Cathedral has just been completed by the authors. The distinct element method was chosen for the static and dynamic analysis of the Cathedral since it can better describe the behavior of the structure, a clearly discontinuous medium. The numerical model consists of deformable blocks and their contacts (a series of nonlinear springs). With such a model, discretized and connected blocks can deform and move (slip, separate, break, rotate, fall) practically without restrictions. The paper discusses the choice of input data for modelling materials and load-bearing elements. The basic principle is to adjust the input parameters of the elements and springs so that the characteristic points on the response curve (forces with associated displacements) correspond to those obtained from numerous well-documented experiments. The problem of the size of the elements with respect to the size of the model is addressed. Three benchmarks are made: block on block, and a shear cyclic wall test for a very wide wall (squat) and a wide wall.

Damir Lazarević, Petra Gidak, Elizabeta Šamec, Antonia Jaguljnjak Lazarević, Krešimir Fresl
Seismic Performance and Retrofit of a Mid-Rise Post-second World War Residential Building Made of Unreinforced Masonry

The housing and economic crisis in Central and Eastern Europe after the Second World War led to construction based on functionalist architectural patterns, which was reflected in the emergence of the first major urban residential agglomerations. Many examples of such buildings have been built also in Slovenia, mostly between 1945 and 1964, when the new building code after the 1963 Skopje earthquake has been issued. The rationale of this paper is to examine the seismic performance and retrofitting possibilities of such residential multi-story buildings, which mostly have regular geometry and are from three to six stories high. The vertical load-bearing structure is usually made of unreinforced masonry (URM) load-bearing walls, and the floor slabs are made of prefabricated reinforced concrete joists with hollow clay brick infills. Such structural systems often do not contain wall ties, and the connection of the walls with the floor slab is often not ensured. This significantly reduces the seismic resistance of such buildings. In the first part of the paper the URM buildings from this era are described based on their architectural, geometrical, and structural features. A general structural resistance to horizontal loads of the buildings has been questioned by comparison with the requirements of modern seismic codes (Eurocode 8). The second part presents numerical simulations carried out on by non-linear static (pushover) analyses. The seismic demand of several analyzed variants has been analyzed by the N2 method with the aid of TREMURI computer program. Various variants with different positions of seismic retrofitting interventions with Fiber Reinforced Cementitious Matrix (FRCM) were analyzed and compared in terms of their strengthening efficiency. Preliminary results show that a combination FRCM and other more invasive retrofitting techniques would be necessary for the examined building to reach the code-based compliance criteria.

Simon Petrovčič, Petra Prašnikar, Vojko Kilar
Seismic Vulnerability Study of Historical Building with Artistic Assets Considering PBA Approach

For historical structures in seismic regions, earthquake often presents one of the highest risks for their damage or, in extreme events, even collapse [1]. In historic structures, artistic assets attached to the structural elements are often of great importance and value but are however commonly even more vulnerable to earthquakes since they exhibit more damage already in less strong, more frequent seismic events. Seismic performance-based assessment (PBA) with nonlinear analysis methods offers a possibility to evaluate the earthquake hazard levels in correspondence to appointed performance limits associated with structural and non-structural damage of interest [2, 3]. To conduct such analyses, high level of knowledge of the analysed building is required as well as in-depth, experimentally supported knowledge of the seismic behavior of the built-in materials and structural and non-structural elements.Since very few experimental tests on the seismic performance of artistic assets attached to the walls exist [4], the paper presents detail results of experimental study where damage of plasters attached to stone masonry walls under in-plane lateral loading was studied. The results served to conduct a deterministic PBA of an actual historical heritage building, a renaissance mansion, where besides structural damage also damage on frescoes attached to the walls is considered.The analysis shows that the analysed building would sustain a 177 years return period earthquake. It also shows that the maximum ground accelerations for performance levels considering significant damage of frescoes are rather high compared to performance levels related to structural elements and that the frescoes would not be destroyed prior collapse of the building due to flexural damage mechanism of the walls to which they are attached.

M. Kržan, V. Bosiljkov
Nonlinear 2D and 3D Finite Element Static and Dynamic Analyses of the Main Pyramid of Huaca de la Luna, Peru

Huaca de la Luna is a monumental earthen complex near Trujillo in north coastal Peru built from 200 AD to 850 AD by the Moche civilization. Its principal structure – a stepped pyramid built with millions of adobe bricks on sloping bedrock and soft soil – presents severe structural damage at the NW corner. The static and dynamic response of the pyramid is systematically analyzed using 2D and 3D nonlinear FE models derived from a detailed evaluation of archaeological, material, and geotechnical data. The analyses are performed in Abaqus/CAE Explicit using concrete-damaged plasticity and Mohr-Coulomb formulation for adobe construction and soft soils, respectively. The time-evolution of elastic strain and dissipative plastic energy is used to follow the development of local damage conditions up to structural collapse. A critical cross-sectional configuration is identified through 2D FE plane strain sensitivity analysis of the static and lateral capacity to (a) pyramid stepped west side profile, (b) underlying bedrock configuration, and (c) adobe tensile strength. 3D models derived from the 2D critical configuration are then evaluated in terms of static stability, lateral capacity, and failure mechanisms. Results indicate that horizontal accelerations produce large structural failure at the pyramid northwest corner similar in extent and location to the present damage.

Selman Tezcan, Miguel A. Pando, Rafael Aguilar, Renato Perucchio
Effect of Eastern Architecture and Sloping Foundation Conditions on the Static and Dynamic Response of the Adobe Pyramid Huaca De La Luna (Perú)

The Moche civilization constructed the monumental adobe complex Huaca de la Luna in phases from 100–650 CE. Its main stepped pyramid is the focus of this study. Located at the foot of Cerro Blanco, near coastal Trujillo, Perú, the structure is subject to Pacific Ring of Fire seismic activity. Damage to the northwest corner and looting on the north and west façades have motivated structural analysis using nonlinear FE models that treat the base of the pyramid as directly attached to the underlying sloping bedrock and soft soil. The present work introduces the following factors to a 2D cross-section model: (a) an interposing sand layer of varying thickness between the adobe construction and the sloping bedrock of Cerro Blanco, (b) a frictional interaction at this interface, and (c) architectural additions to the main pyramid’s east side. Using a Design of Experiments (DOE) methodology, this study investigates how these factors affect the monument’s lateral capacity, measured through the time-evolution of strain and plastic dissipation energy. Results indicate that the interposing sand layer and construction on the east side influence the results the most. Consequently, further on-site survey should focus on a more accurate definition of these features. Simulations are performed in Abaqus/CAE Explicit using the concrete damaged plasticity and the Mohr-Coulomb formulations for modeling adobe and sand, respectively. Statistical analysis is performed in the statistical software JMP version 16, primarily focusing on Analysis of Variance (ANOVA).

Anna M. Remus, Lale Yılmaz, Selman Tezcan, Renato Perucchio
Analysis and Design of Strengthening for Two Facades of Movie Theaters in Gomez Palacio and Piedras Negras, México

This paper contains the analysis and design of the strengthening structure to preserve two facades of mid-twentieth century movie theaters in two cities located in the north region of México. In the two cases, the new owner recycled the buildings to use them as a home appliance and furniture store, with some adaptations. However, in recent years, it was decided to demolish the existing buildings to build new structures. Municipality regulations required in both cases, to include the preservation of the facades in the new project. The purpose of this paper is, firstly, to present the considerations made for the analysis of the existing structures and the design of the strengthening scheme, and secondly, to document the importance of the preservation of these two facades.Both facades, different in geometry, but similar in the conceptional solution, were strengthened by leaving part of the lateral walls, resembling buttresses at each side of the main plain of the façade, and by incorporating steel trusses that mimic the stiffness provided by the roof of the original structure. Connections were made with steel anchors in concrete members, and steel rods in masonry walls. Wind forces rather than seismic actions controlled the design. Both projects were finished by the second semester of 2022.

Oscar Minor-Garcia, Hector Mendoza-Olivares, Alavez-Perez Gerardo
Seismic Performance Assessment of a Stone Masonry Building in the Historic Core of Dubrovnik

The city of Dubrovnik is located in a seismically very active region, with the reference peak ground accelerations exceeding 0.3g for 475 years return period earthquakes. Therefore, it is essential to perform seismic assessment of the existing buildings and retrofit them accordingly. This paper presents the results of the seismic performance assessment of a typical residential stone masonry building in the historic core of the city. The building is about 400 years old and of very high cultural value as the Old City of Dubrovnik has been under the protection of UNESCO since 1979. The vulnerability of this type of buildings is high which has been demonstrated in the earthquakes that have struck the city throughout history. The seismic assessment of a stone masonry building is a very challenging task. Therefore, a complex numerical model was created in Abaqus software to perform a detailed seismic performance evaluation. Used material model considers the complex stress state and yielding of the material with degradation of mechanical parameters under cyclic loading. Nonlinear dynamic analyses were performed using time-histories that were carefully selected for the site. To process the results and conduct verification with parameters commonly quantified in seismic standards, a Python script was created so relevant response quantities are determined. Finally, some conclusions regarding critical elements of the structure are highlighted.

Mario Uroš, Marija Demšić, Maja Baniček, Petra Gidak, Marta Šavor Novak, Jakov Oreb, Josip Atalić, Ivan Duvnjak
Quantitative Evaluation Method of Structural Safety Status of Ancient Chinese Nine-Hole Stone Arch Bridges—A Case Study of Putang Bridge

Ancient Chinese stone arch bridges are different from ancient Western stone arch bridges in terms of bridge form, bridge structure, bridge material and construction technique. In order to clarify the structural safety status of this type of stone arch bridge and provide a scientific basis for subsequent conservation, an appropriate quantitative evaluation method of structural safety status is proposed for the ancient nine-hole stone arch bridges. Taking the typical nine-hole stone arch bridge, Putang Bridge, as an example, first, a structural safety evaluation system for the bridge was built up according to the bridge form and bridge structure. Then, an improved analytic hierarchy process method based on component importance analysis was proposed to obtain the weight coefficients of the main structural components of the bridge. Finally, the structural safety status of this bridge was quantitatively evaluated with the proposed method. The results can provide a reference for the quantitative evaluation of the structural safety status of ancient nine-hole stone arch bridges.

Qing Chun, Bei Peng, Huan Song, Yidan Han

Open Access

Guidelines for Seismic Retrofitting of Earthen Historic Buildings in Peru and Latin America

The development of guidelines for seismic retrofitting of earthen architectural heritage has been part of the intended outputs of the Seismic Retrofitting Project – a partnership between Getty Conservation Institute and the Ministry of Culture of Peru – since its inception. The results of the Seismic Retrofitting Project are currently being reframed to become part of a document written by the Ministry of Culture of Peru, with the support of Getty Conservation Institute staff and consultants, that will guide in the structural analysis, diagnosis, and design of effective structural interventions to conserve earthen constructions and transmit their significance. The document will advise local practitioners, ease their collaboration with the Ministry of Culture of Peru, and possibly become part of the Peruvian regulatory framework, with a broader impact in Latin America. This contribution describes the methodology to collaboratively create the guidelines, ensure their dissemination in the region, and the results obtained to date.

Elena Macchioni, Claudia Cancino
Distinct Element Method Analyses for Damage Assessment: The Case of the Valverde Bulwark in the Venetian Fortress of Bergamo

The 16th-century Venetian Fortress of Bergamo is a complex defensive system over 5 km long with more than 70,000 m2 of masonry wall facing, inscribed to the UNESCO world heritage list in 2017. Today, the first causes of its deterioration are the vegetation growth and the lack of maintenance that have led to instabilities and local failures, particularly in the north-west portion. Thus, in 2019 and 2020, survey campaigns were carried out to assess the safety of one of the most damaged sections, the Valverde bulwark. The survey combines on-site observations, laboratory tests, and photogrammetric and laser scanner surveys to describe the state of the bulwark.Some numerical simulations have been performed within a Distinct Element Approach (DEM). DEM has been conceived for geo-mechanical analysis, such as caves or mines; however, several researchers have widely proven its application to masonry structures. It assimilates the masonry to a system of discrete bodies consisting of blocks (usually rigid) interacting on their interfaces. DEM analyses are usually executed on simplified models, rarely considering the actual geometry of the masonry structure due to the extremely time-consuming and the usual lack of information. Within the research, a routine dedicated to defining a real-like geometrical model has been developed. The numerical analyses were run to understand the condition of the Valverde bulwark in the actual state, analysing the conditions under self-weight and earth pressure and the behaviour under seismic loading. Through the detailed survey and its automatic digitisation, it is possible to fully recognise and analyse the state of health of these historical structures as well as their mechanical behaviour.

F. Gobbin, V. Paris, V. M. Nannei, G. Mirabella Roberti
Seismic Testing of Adjacent Interacting Masonry Structures – Analysis of a Blind Prediction

Masonry aggregates, which emerged as layouts of cities and villages became denser, make up historical centres all over the world. In these aggregates, neighbouring structures may share structural walls that are joined at the interfaces by mortar or interlocking stones. For instance, observations following the recent earthquakes in Italy and Croatia frequently revealed symptoms of separation and pounding at interfaces because of the out-of-phase behaviour of the units.The analysis of such building aggregates is complicated by the missing guidelines, as the scarce experimental data prevented the advances. Therefore, the objective of the project SERA AIMS (Adjacent Interacting Masonry Structures), included in the H2020 project SERA, was to create such data by testing an aggregate of two buildings under bidirectional dynamic excitation. The test unit was built at half-scale, with a two-storey building and a one-storey building. The buildings shared one common wall with the façade walls connected only by a layer of mortar, without interlocking stones. The floors were at different heights and had different beam orientations to facilitate the out-of-phase response. First, the shake-table test and main findings are briefly discussed. Second, blind-predictions coming from a dozen of research groups and consultancies are reported and compared with the experimental results. The comparison of blind-predictions and experimental results was based on quantitative comparison of reported displacements and base shear-values, and qualitative comparison of observed damage mechanisms. Submissions were grouped according to modelling approaches and key modelling assumptions to derive conclusions on their impact on the results.The work presented in this paper confirmed that even when the material parameters are known, and all the participants start from the same starting point – uncertainties related to modelling unreinforced masonry aggregates are such that predicted results vary greatly both in terms in reported displacement, interface opening, and damage mechanisms. Additionally, when compared to experimental results, correct predictions were rare – leading to the conclusion that there are many remaining uncertainties that have to be addressed when modelling this widespread building typology.

Igor Tomić, Andrea Penna, Matthew DeJong, Christoph Butenweg, A. A. Correia, P. X. Candeias, Ilaria Senaldi, Gabriele Guerrini, Daniele Malomo, Katrin Beyer
Damage Classification of Sacral Architecture After the Earthquakes in Croatia

Croatia was hit by two devastating earthquakes in 2020. Almost 80,000 buildings were damaged, several thousand of them severely. The total number of affected buildings in the cultural heritage sector includes 192 cultural institutions, 13 state cultural heritage buildings and 159 religious’ buildings after the March 2020 earthquake. Following the Petrinja earthquake in December 2020, 442 immovable cultural properties were damaged, including 124 cultural heritage buildings (28%) that suffered severe structural damage. The largest number of damaged cultural heritage buildings concerns sacred buildings, mainly churches and chapels. In this paper, a brief overview of the damage in the cultural sector after the earthquakes in Croatia is presented. A classification of the damage to both individual cultural properties and buildings in heritage zones in the affected cities is provided. In addition, special emphasis is placed on sacred architecture and damage to churches and chapels in earthquake-affected regions. The damage patterns are presented through several case studies. The condition assessment after an earthquake and the definition of the mechanical properties of masonry elements are briefly explained using several case studies.

David Anđić, Mislav Stepinac, Juraj Pojatina
Seismic Risk Mitigation of a Long-Span Historical Building Through a Wooden Roof-Box Structure

Seismic risk mitigation measures for historic buildings often encompass the introduction of perimeter ties, or floor and roof diaphragms to prevent the onset of local mechanisms, particularly the out-of-plane mechanisms. Among the retrofit strategies, roof diaphragms, first adopted for the seismic retrofit of churches, are nowadays commonly used for all building types. More recently, the solution has been even more appreciated because, unless static problems exist, it does not require the building downtime, nor the relocation of the building inhabitants/functions, which are acknowledged as the major obstacles to any retrofit initiative. Roof diaphragms are designed to adsorb the seismic action of both the roof and the out-of-plane loaded walls and transfer it to the seismic-resistant walls. A proportioning approach was introduced by Giuriani and Marini; the approach considers the lateral load-resisting system (the box structure) as composed of the roof pitch diaphragms and the headwalls, while the longitudinal walls are modeled as trusses, only transferring their inertia forces to the pitch diaphragm. Such a simplified model was effective in the design practice for proportioning roof diaphragm components in regular buildings. In the case of oblong buildings, however, an enhancement of the analytical model was recently proposed, to account for the interaction of the roof diaphragm with the longitudinal masonry walls, which are therefore introduced in the lateral resisting system. Such an upgrade allows for a more accurate representation of the global 3D behavior of the lateral load-resisting box structure, leading to a more realistic prediction of the internal actions, with the advantage of significantly reducing the axial forces in the compressed longitudinal eaves chords of the roof diaphragm. In this paper, the enhanced simplified analytical model is applied in the context of the seismic retrofit of an oblong historical reference building operated with a wooden roof diaphragm. The effectiveness and drawbacks of the enhanced approach are critically commented on.

Simone Labò, Alessandra Marini, Ezio Pilar Giuriani, Jacopo Zanni, Paolo Riva
Seismic Retrofitting of Heritage Structures, Actual Techniques and Future Challenges for Earth and Masonry Constructions

While rammed earth structures are a sustainable design alternative, they are particularly vulnerable to horizontal forces such as seismic loads. Traditional seismic design techniques follow four main principles. (i) Improving connections and forming closed contours. (ii) Stabilizing structural elements by providing resistance and deformation capacity, and by improving the diaphragm action of floors. (iii) Allowing partial collapse through redundancy of structural elements. (iv) Counteracting horizontal loads by providing additional resistance with new structural elements. In this work, special attention has been given to external reinforcements such as TRM (Textile Reinforced Mortars), which have given good results in masonry walls. The references of the use of TRM in earthen walls are scarce, but TRM has been found to increase the compressive and shear strength and ductility of rammed earth. In this paper, special attention is given to the bonding phenomena based on experimental results with TRM reinforced masonry elements. Even in cases with severe damage due to fire exposure, TRM could improve the mechanical response of masonry walls under combined gravity loads and in-plane cyclic shear forces. Carbon fibers showed the best performance after high-temperature exposure, but debonding failure can occur when the TRM-masonry interface is damaged. In the case of TRM applied to rammed earth walls, the bonding between the two materials is expected to be poor; therefore, special connectors would be required to ensure anchorage of the TRM to the earth surface.

F. Javier Baeza, Luis Estevan, Salvador Ivorra
Evaluation of the Seismic Behaviour of an Inca Stone Wall Using Rigid Body Dynamic Methods

Peru has around 7 360 prehispanic archaeological monuments [1] according to the Ministry of Culture of Peru. These structures, built with irregular shapes and variable configurations, are very complex to evaluate. Unfortunately, some of these constructions are in poor conservation state due to external factors such as earthquakes, soil settlements or human activity [2]. For example, some Inca culture stone walls from archaeological sites such as Puka Pukara, Sacsayhuaman, Huchuy Qosqo and Chinchero present visible damage directly associated with previous earthquakes [3]. In this research, the dynamic response of an Inca stone wall from Sacsayhuaman is evaluated using rigid body dynamics in Abaqus [4]. Sacsayhuaman archaeological site is made up of enormous retaining walls with large carved stones and dry joints. The stones were modelled with their irregular shapes as rigid bodies and their interactions by means of interfaces with normal and shear stiffness. All mechanical properties were adequately calibrated based on experimental tests and literature review. The results confirm that the use of rigid body dynamic methods can help to evaluate the seismic performance of stone structures and to identify the most probable collapse mechanisms during a seismic event.

Leonel Lipa, Nicola Tarque, Luca Pelà, José María Goicolea
Seismic Performance and Vulnerability Analysis of Traditional Chinese Timber Architecture Considering Initial Damage

An actual structure was selected for seismic vulnerability analysis (SVA) to study the seismic performance and damage probability of the traditional Chinese hall-style timber architecture under different earthquake intensities. The structural modal parameters and seismic response characteristics were obtained. A finite element model (FEM) of Dacheng Hall in Pingyao Confucian Temple, Shanxi Province, was established based on field measurement data, considering column inclination and material degradation, and was verified by field dynamic characteristic test. The seismic probability demand analysis of FEM was carried out after incremental dynamic analysis (IDA) and the SVA of Dacheng Hall was studied, taking the ground peak acceleration (PGA) and the maximum inter-story displacement angel as the ground motion intensity index (IM) and response parameters (DM), respectively. The probability of suffering minor damage for damaged structure under the minor earthquake (PGA 0.07 g) is about 61%. The most likely damage state of Dacheng Hall under moderate earthquake (PGA 0.2 g) is moderate damage and the occurrence probability is 75%. The probabilities of severe damage and collapse of the damaged structure under the major earthquake are about 72% and 12%, respectively. The collapse probability of damaged structure under the major earthquake is low, which reflected the excellent seismic performance of ancient timber buildings.

Qingshan Yang, Meng Zhou, Ke Liu
Research on Seismic Performance of Traditional Chinese Ganlan Timber Structure: A Case Study of Tujia Village in Western Hubei Province

The traditional Ganlan timber frame (pile-built timber construction) is a typical construction widely used in the vernacular architectural heritage in Southeast Asia. It is built to adapt to the warm and humid climate and complex mountain terrains. The traditional Chinese Ganlan buildings are primarily distributed in the region with high seismic hazards, and the complex construction system makes accurate seismic performance evaluation a difficult task. Taking Ganlan building of Tujia village in southwest Hubei Province as an example, an efficient and scientific performance-based seismic evaluation method is proposed. First, the geometric information of Ganlan buildings is obtained from three-dimensional scanning and on-site investigation. The established finite element models are modified through low-cycle cyclic loading tests of mortise and tenon joints. Then, to quantify the global seismic performance levels of the structures, the nonlinear static pushover method is used to analyse the seismic performance of the Ganlan building, and the dynamic characteristics and story drift ratios of the structure under three working conditions are obtained. Finally, the local failure modes of the structure are determined by order of modified plasticity hinges generation. The research results can provide a scientific basis for the structural performance research and subsequent reinforcement research of Ganlan buildings.

Yijie Lin, Qing Chun, Chengwen Zhang
Preliminary Assessment of a Historic Masonry Church Strengthened by Reinforced Concrete Elements During 1927–1930. The Case of Recoleta Dominica Basilica in Santiago, Chile

One of the main issues of heritage preservation in highly seismic areas is the compliance between structural safety requirements and conservation criteria. In Chile, from the beginning of the 20th century to the present time, 17 megathrust earthquakes have shocked the country around the Chilean central valley. The most recent and destructive of them, the 2010 (8.8 Mw) Maule earthquake, damaged 52% of Historic Monuments and Pinteresque Zones around the Central Valley, where 60% of them were URM churches.In this context, the paper focuses on the analysis of the efficient seismic performance of a representative example of a neoclassical Basilica, the Recoleta Dominica in Santiago (1853–1883), and an unusual case in the country that has shown a satisfactory seismic response along history. The investigation suggests that its efficient seismic performance can be explained mainly by avant-garde retrofit work carried out early in the 1930s, based on a strengthening system composed of reinforced concrete (RC) beams and columns, which has avoided its collapse and thus, its cultural loss.A preliminary assessment of the seismic behavior before and after the retrofitting interventions, through the Linear Cinematic Analyses of the main mechanisms observed following the 1985 and 2010 earthquakes was carried out. In opposition, the current structural interventions criterion on architectural heritage suggests non-destructive methods and techniques. Further investigations in this field may provide inputs to establish a more comprehensive analysis of this issue, as defining appropriate interventions criterion on this architectural and RC strengthening typologies.

Marco Barrientos, Nuria Chiara Palazzi, Rolando Alvarado, Cristián Sandoval
Preventive Retrofitting Strategies for Archetype Buildings Representative of the Abruzzo Region

The present paper addresses the development of large-scale vulnerability models for masonry buildings with seismic retrofitting interventions in the Abruzzo region, Italy. The proposed work is the result of an Italian Research Project developed within a cooperative agreement between the Italian Network of University Laboratories of Seismic and Structural Engineering (ReLuis) and the Department of Civil Protection (DPC). The goal is to assess the seismic vulnerability at the urban scale through analytical models accounting for the out-of-plane behavior of masonry structures and to evaluate the vulnerability variation between the “as-built” and “retrofitted” configurations. Thanks to an automated procedure developed by the Authors, archetype masonry buildings are first identified to limit the number of buildings object of analyses. These archetypes are defined according to specific parameters selected from the Cartis form, an Italian tool that collects typological-structural information of the buildings present throughout the national territory. Afterwards, based on information retrieved from the literature and on the effectiveness shown during earthquakes, an exemplary seismic intervention is selected and applied to representative buildings with the aim of quantifying their improved seismic behavior. The results obtained from this investigation are shown by means of fragility curves and can be of great support in the definition of cost-effective risk mitigation strategies, allowing to quantify benefits and costs of possible interventions at the territorial scale.

Giorgia Cianchino, Maria Giovanna Masciotta, Giulia Cocco, Giuseppe Brando
Seismic Analysis of a Single-Nave Church Standing on Moderate Sloping Ground: A Church Severely Damaged By the 2009 L’Aquila Earthquake

The present paper discusses the seismic analysis of a structure standing on moderate sloping ground. The case study is San Giovanni Evangelista church in Casentino, Italy. The façade faces the southwest and slope goes down towards the north and east. It was severely damaged by the 2009 L’Aquila earthquake and is under reconstruction. Collapse mechanisms and damage patterns were considered relevant to sloping ground. In this study, the seismic behaviour of the church is examined with a focus on interaction with the sloping ground. A numerical model was prepared based on in-situ and laboratory tests. The single- and double-flat jack tests of a wall and the chemical analysis of mortar were performed. A three-dimensional spring model and plane interface model were used to discretise contact between the superstructure and sloping ground. Pushover and nonlinear dynamic analysis (NDA) are conducted. NDA considers an accelerogram generated from the L’Aquila earthquake. The paper discusses the seismic behaviour of a church standing on sloping ground and suggests an effective approach to the analysis of such structures.

Yohei Endo, Jacopo Magi, Manuel Marotto, Yasutoshi Sakai
Application of Multi-Directional Pushover Analysis to a Multi-Storey Structure Built of Tuff and Welded Tuff Masonry

The seismic assessment of masonry structures has been a major research topic. Although a variety of studies have been conducted, still further investigation is necessary to improve the accuracy of seismic assessment approaches. Earthquakes act on structures in two horizontal axes at the same time. To this am, multi-directional pushover analysis (MDPA) is considered effective to evaluate the behaviour of plan irregular structures under seismic loadings. The case study is a three-storey tuff masonry structure. It is positioned in Hokkaido, Japan. The façade is composed of welded tuff while the other walls are built of tuff. This case study shows irregularity in plan due to the use of different materials despite of simple geometry. A numerical model is prepared based on an in-situ microtremor test and laboratory material characterisation test. Nonlinear dynamic analysis (NDA) was also performed to compare results obtained from MDPA. NDA considered three accelerograms including one generated from the 2018 Iburi earthquake (6.6 Mw). It was one of the most intense earthquakes in Japan in the last 100 years. Comparison between NDA and MDPA examines the applicability of MDPA to plan-irregular masonry structures.

Yohei Endo, Kosuke Kanakubo
The Effect of the Vertical Component of Ground Motion on a Masonry Cross Vault Model

Recent earthquakes have emphasized the high vulnerability of vaulted structures. Their collapse may entail only local damage or can affect the surrounding building because of its heavy mass and the significant horizontal thrust on supporting elements. In this paper, the influence of the vertical component of ground motion on the performance of a numerical model of an unreinforced masonry cross vault is investigated using sets of one-component and two-component ground motions to perform nonlinear dynamic analyses. The set of motions represents the actual seismicity of L’Aquila, Italy, while the investigated vault mimics a reference brickwork specimen. The numerical model falls within the mixed finite–discrete element method and accounts for crack formation, complete separation and new contact formation. The modelling strategy is capable to evaluate the ultimate displacement and load-bearing capacity of the vault under seismic loading and the progressive deformation of the vault up to collapse. The vault is excited by a horizontal component alone or by both horizontal and vertical components. Although without a systematic trend, adding the vertical component worsens the response in about 10% of cases.

O. AlShawa, D. Liberatore, L. Sorrentino
Improving the Seismic Response of Masonry Piers with Single-Sided FRCM Coating Using Clamping Details – Numerical Modelling

As a building material, masonry is one of the most used materials in the world. According to various literature, approximately 70% of the world’s building stock is built in masonry. Even though there are many advantages of masonry, the greatest disadvantage is the seismic vulnerability that masonry structures display, especially those considered cultural and historical heritage. The tensile strength of masonry is very poor, leaving masonry structures vulnerable to horizontal actions [1]. This fact is not surprising since most of these buildings were designed and built before the development of adequate seismic provisions. Therefore, the retrofitting and strengthening of such buildings is critically needed.Nowadays, besides the traditional retrofitting methods, modern strengthening technologies are emerging. One of the most used ones is the Fabric-Reinforced Cementitious Matrix (FRCM) method. There are numerous advantages to FRCM, one of which is that FRCMs can be installed under unfavorable conditions, such as cold and damp masonry surfaces and under high temperatures. Besides that, this method can be used in brick [2] and stone masonry [3].This paper will explain the numerical modelling of FRCM-strengthened masonry piers in the DIANA FEA software. A micro-modelling approach is chosen for the most detailed analysis of the pier’s behavior. The paper’s primary goal is to introduce an improved FRCM layout and to explain all the problems that occurred during the numerical modelling of the strengthened masonry piers. Furthermore, all advantages and disadvantages of micro-modelling of strengthened masonry piers will be examined.

Ivan Hafnerq, Tomislav Kišiček, Matija Gams
Static and Seismic Assessment of a 20th Century Architectural Masterpiece: Artemio Franchi Stadium in Florence

A static and seismic assessment study of “Artemio Franchi” Stadium in Florence is presented in this paper. The study is based on the documentation collected on the original design of Pier Luigi Nervi and the refurbishment works carried out for the World Football Championship of 1990, as well as on extensive on-site experimental campaigns aimed at attaining an adequate knowledge level of the reinforced concrete structure. These campaigns included tests concerning the mechanical properties of the materials and checks on local reinforcement details, and dynamic characterization tests on the bleacher blocks constituting the structure and Maratona Tower. The results of the diagnostic investigations prompted the generation of a complete and detailed finite element model of the Stadium, by which its static conditions and seismic performance were evaluated. A synthesis of the architectural and structural survey, the testing campaigns and the computational analyses is reported herein.

Gloria Terenzi, Elena Fuso, Stefano Sorace
Seismic Behaviour and Strengthening of Rammed Earth Constructions

The widespread use of earthen buildings can be accredited to the local availability of the raw material, sustainability of the building process, and low cost. Earthen structures suffer from high seismic vulnerability, resulting from the low strength of the material, high mass, and lack of engineering approaches in design and building. Despite the extensive use of rammed earth structures, the structural behaviour of such buildings is still not well known, particularly concerning the in-plane and out-of-plane response under cyclic loads. Moreover, proper strengthening solutions are still required to reduce seismic vulnerability. In this context, an experimental program was conducted on the in-plane and out-of-plane cyclic performance of rammed earth structural sub-assemblies. The prototypes, after being damaged, were strengthened by employing a TRM-based solution and subjected to further testing. The experimental results are reported and discussed in terms of cracking pattern and peak base shear coefficient. Finally, the effectiveness of the proposed strengthening solution was evaluated against the performance of the unstrengthened mockups. The outcomes highlighted the effectiveness of the TRM solution in improving the ductility and the in-plane shear capacity of the mockups.

D. V. Oliveira, A. Romanazzi, R. A. Silva, A. Barontini, N. Mendes
Seismic Retrofit of a URM Building with Timber-Based Coating: A Numeric Study

This work investigates the effectiveness of timber-based coatings in improving the seismic behaviour of unreinforced masonry buildings. The present study focuses on the seismic behaviour of a full-scale building retrofitted with the aforementioned technique and investigated numerically. The retrofit strategy consists of connecting timber-based panels to the surface of the building walls using mechanical or adhesive point-to-point connections spread over the wall surface. The retrofit allows a considerable increase in both the in-plane and the out-of-plane capacity of the masonry walls. The timber panels can be fixed on the internal or external side of the building walls. Membranes, insulation layers and finishing layers can be added to the retrofit to ensure the durability of the timber products and improve the thermo-physical performance of the building. A detailed modelling approach was developed, building on previous analyses performed by the authors on retrofitted masonry piers and walls with openings, to assess both the global and the local behaviour of a retrofitted masonry building and to provide data that could be used as reference for the calibration of less refined, yet computationally more efficient, macro-element models. Various retrofit configurations were analysed, considering the timber panels applied to the entire perimeter walls of the building or to selected elements (e.g., retrofit applied to masonry piers alone or both piers and spandrels) and involving different geometries influenced by the maximum panel transportable size. The effectiveness of the retrofit configurations was evaluated in terms of increased lateral load and displacement capacity through non-linear simulations.

Davide Cassol, Edoardo Nagliati, Ivan Giongo

Management of Heritage Structures and Conservation Strategies

Past Reconstruction and Future Forecast of Stone Durability: The Case Study of the Trondheim Cathedral

The study of climate change impact on the built environment using historical weather data, and forecasts, and climate scenarios, is an important mean to understand both the modification occurred on materials over past decades and those expected over the future.The aim of the present contribution is to investigate how the stone durability in the built environment has been affected by temperature modification since 1951 at high latitudes.To achieve this objective air temperature retrieved by weather stations and satellite remote sensing instruments have been analysed using the Global Land Data Assimilation System (GLDAS) product over the 1950–2020-time span. This product has then been compared with the COSMO-CCL COnsortium for Small-scale Modelling [1] data for climate predictions in the far future (i.e., FF = 2071–2100). The Representative Concentration Pathway scenario selected was the RCP4.5 - stabilization scenario [2]. Both the datasets have been retrieved over the location of the Nidaros Cathedral (NC) in Trondheim (Norwegian: Nidaros domkirke), Norway that represents the high latitude case study of this contribution. Data processed through Fast Fourier Transform and percentile analysis show how the climate change impact is manifested at NC. Over the years, temperature shows a most pronounced variance modification rather than a marked increasing trend that in turn affects the number of freezing-thawing cycles process with consequences on cracks and spalling of stones [3].The average stone durability assessed in this study is of support to conservators, architects, and restorers to effectively and timely plan restoration intervention of NCT stones.

S. Cavazzani, M.-L. Anker, C. Bertolin
Restoration Study and Re-use of the Listed ‘Olympios Tower’ and Its Accompanying Buildings in Ano Lechonia, Western Pelion, Magnesia Prefecture, Greece

This project concerns the restoration of the listed monument known as the ‘Olympios Tower’ and its accompanying buildings at Ano Lechonia, a lowland fertile village in Magnesia Prefecture in Greece. The original core of the Tower dates back to the 17th -18th centuries and consists of an almost rectangular plan of 6,91 × 7,05 m, with a fortified base. In 1860, there was an addition made to the Tower’s north face, thereby creating a final L-shape plan and causing major alterations to the original building. Next to the Tower, there are two, two-storey accompanying buildings with auxiliary uses related to the storage and pre-industrial processing of agricultural products. The complex has suffered from lack of repair and maintenance and needs immediate restoration in order to be saved as a noteworthy architectural ensemble.The purpose of this study is the restoration and re-use of the ‘Olympios Tower’ complex in order for it to be re-used and maintained as a traditional guest house and restaurant with emphasis on local gastronomy and wine tasting. The restoration is based on respect for authenticity with an interdisciplinary approach. This paper aims to present not only the structural interventions, but also the challenges that derive from such a re-use, where the experts involved are consulted, on the one hand, to design all necessary interventions with care by minimising the impact on the original canvas, while, on the other hand, adding another layer to the complex that is contemporary and yet corresponds to its values.

Fotini Chalvantzi, Ifigenia Dimitriou, Konstantinos Toumpakaris, Maria Mageirou
Connectivity and Conservation: A Critical Examination of the Relationship Between Infrastructure Development and Cultural Heritage Perception in Chiang Mai, Thailand

Chiang Mai, capital of the Lanna Kingdom (1292–1775), is poised to submit a final dossier to UNESCO (United Nations Educational, Scientific and Cultural Organization) by 2025 to become a World Heritage Site. Chiang Mai’s application reveals complexities related to Lanna-ism, or the city’s “northern identity” that is different from central-Thai-based identity, and evokes tensions between local, national, and global imaginations of a heritage city. This paper aims to contextualize as well as contribute to the ongoing debates about Chiang Mai’s potential world heritage status and its Lanna identity by examining the relationship between the development of infrastructure and its influences on the perception of cultural heritage from the 19th to the 20th century. Built environments are historical constructions defined by the connectivity and accessibility of a city. Specifically, infrastructure at diverse scales potentially influences the function, narration, and interpretation of a heritage city. This paper focuses particularly on two detailed case studies at distinct yet inter-related scales. The first case study investigates the conservation of the Phra That Doi Suthep temple which infrastructure of different scales challenge the heritage agency and raise a question toward the practices of neglecting and keeping the significance value of heritage. The second case study at urban scale focuses on the transformation of the Thapae Gate located on the east side of Chiang Mai city wall, which was deconstructed and then reconstructed in the late 20th century in response to the enlarging roadway construction that leaves no space for urban citizen to interact with their historic city. Both railway and roadway developments trigger tensions between embracing the city’s identity and labeling the city as a tourism destination which later ultimately raise questions about who has the right to access and enjoy the cultural heritage of Chiang Mai.

Kanisa Sattayanurak
The Dialectic Between Heritage Value and Seismic Safety: How to Achieve a Better Balance

Proper treatment of patrimonial structures requires laser-like focus on preserving the heritage value of the structures, while accounting for their inherent seismic resistance and resolving critical vulnerabilities. This is a balancing act – a give and take – that is not for the faint of heart and is one about which there is limited, sometimes conflicting, direction set forth in published engineering guidance documents. Seismic goals ought not always dictate the outcomes of projects that involve patrimonial structures. Acknowledging the dialectic between preservation and seismic safety means accepting that the need to safeguard heritage value might sometimes limit the possibility of meeting certain seismic performance targets. Strategies for rising to the challenges that the dialectic presents are the subject of the paper.

Terrence F. Paret
Structural Design of the New Roof for the Aztec Temple Casa De Las Águilas

This paper contains the considerations, structural analysis, and design of a new roof for the Casa de las Águilas temple, on the Templo Mayor archaeological site in Mexico City. Built around 1982, with the aim to protect the remains of the Aztec temple from sunlight and weather conditions, the previous tridimensional steel truss roof protected the site until April 28th, 2021, when a massive hailstorm caused its collapse. Fortunately, no significant damage was made to the archaeological remains. Forensic analysis was made to determine the cause of the collapse, resulting that the steel elements of this structure did not have the sufficient strength to resist the design loads, and failed in the tension elements due to overload. A new structure was projected,. On the evening of April 28th, 2021, the tridimensional steel truss roof that covered the Casa de las Águilas collapsed due to the accumulation of ice during a hailstorm. The structure, rectangular in a floor plan, and with supports on the north and on the south, behaved like a simply supported beam, with a uniformly distributed load. The maximum forces were presented at the midspan. The structure fractured on the tension members in the lower chords, creating an additional hinge that made the structure unstable. The structure collapsed like an open book, with two planes divided at the center. Forensic analysis was initially made to determine the cause of the collapse of the original roof, aimed to prevent this to happen in the new structure. With the results and the specifications created by the National Institute of Anthropology and History (INAH), the design of the new structure was made. Seismic, wind and hailstorm loads were considered. Tests were made to verify the strength of the connections.

Oscar Minor-Garcia, Miguel Gallardo-Contreras
Urban Ruins in Inhabited Historic Settlements. A Preliminary Study for Safety Improvement of the Public Spaces of the Granfonte District in Leonforte (Sicily)

This article presents a segment of an ongoing research project on the Granfonte district, the oldest area in the town of Leonforte, located in the heart of inner Sicily. The neighbourhood lies on a steep rocky slope, which has influenced the local architecture and constructive solutions. Traditional houses are examples of essential dwellings, where farm and domestic life are often combined due to the limited space in the urban sites, and today they remain as rare witnesses of vernacular architectures. However, depopulation and city expansion policies since the 1960s have caused the district to become increasingly abandoned, leading to decay in the built fabric. Unfortunately, the local administration has been demolishing dilapidated buildings with no regard for urban quality, thus jeopardizing safety and conservation objectives. In this framework, a part of the research work on the Granfonte quarter focuses on developing a project to revitalize public spaces and urban ruins to regenerate the built environment and ensure safety. The intervention criteria are designed to delay the demolition of ruined buildings by integrating them into public spaces and preserving their architectural integrity with minimal demolitions. The paper outlines the preliminary results of the study, focusing on knowledge of local construction techniques, mapping of unstable elements and situations, and providing general observations regarding guidelines for interventions.

C. Circo, I. Cacciatore, M. Massimino, D. Sanzaro
Emergency Response to Damaged Architectural Heritage: Time, Safety and Conservation

The balance between conservation and safety is always a tough issue when dealing with built heritage. Especially in emergency conditions – after an earthquake or a war – an effective balance between cultural and structural issues is difficult to reach because of the urgency of securing a huge number of damaged buildings and monuments. In these cases, several first aid interventions turned out to be harmful or ineffective for the conservation of historic buildings, as they were realized looking only for short term stability requirements.However, Italian Guidelines suggest the possible use of first aid techniques as definitive interventions because of their reversibility, feature highly recommended in restoration interventions. Therefore, emergency techniques were studied in order to define a methodological approach for securing the built cultural heritage in consideration of both structural and preservative issues. In the specific, the most widespread techniques used as provisional reinforcement in the 2012 Emilia earthquake were analyzed, considering their structural efficiency and their compliance with the conservation principles. To this purpose, some examples are presented, underlying criticalities and potentialities.This analysis highlights that the design of urgent interventions cannot address only to the emergency phase, but it must be considered as a part of the overall conservation process, that goes from the survey of damages to the final restoration. In this regard, the management system and response plans deeply influence the effectiveness of first aid on architectural heritage. Some consideration about effective methods to balance structural and conservative issues in emergency conditions are presented, as a hint to improve awareness and emergency preparedness.

Eva Coïsson, Lia Ferrari
Conservation, Consolidation and Restoration of Holy Annunciation Church of Vătășești Village, Region of Oltenia, Romania

The present article discusses the process of structural consolidation and architectural restoration of a late 18th century, brick masonry built, orthodox church located in Vătășești village, Vâlcea county, Romania, presenting the complete process of diagnosis, the edited structural and architectural projects, also the completed conservation and restauration works. The church is dedicated to Saint John the Baptist and The Holy Annunciation and it is listed under the LMI code (List of historical monuments of Romania) VL-II-m-B-09968. Its registration in the list of historical monuments inscribed in the National Cultural Heritage of Romania was realized especially thanks to its original byzantine style mural paintings (frescoes) still left almost intact on the interior walls, the only serious damage made to it being found on the paintings once found on the outside walls. The purpose of this article is to show the steps of the restoration process applied in this example, starting with the methods of diagnosis, such as the drawn survey, photographic documentation, 3D scanning using laser scan technology, topographic report, geological report, archeological report, structural analysis using 3D modelling and the Etabs software, the report of mural paintings conservation and restoration experts, chemical analysis of the painted surface and humidity reports. The materials and techniques used for the consolidation and restoration works are non-ivasive, ecological and reversible, using steel nets and hydraulic lime for the consolidation of the brick masonry. The architectural interventions on the drainage system, facades, roof, interior floors, lighting system, and all the interventions that the article describes were subordinated by the need to preserve and highlight the Romanian orthodox frescoes that give great value to the monument.

Marius Moșoarcă, Traianus Popovici, Tamara Roseti
Renovation Planning Strategy to Prevent Building - A Case Study

Failure to carry out repair work is an extremely important factor in causing further damage to buildings. A damaged element can cause a threat to the structural stability of the building, a threat to the lives of the occupants, further damage to the building by damaging subsequent elements. The aim of this article is to analyse the consequences of abandoning repair work and to present a repair strategy resulting from these consequences. The article presents the problems associated with the abandonment of renovation works of damaged elements. A classification of the consequences of the abandonment of renovation for historic buildings is developed. Buildings that have not been used for a long time are degraded, the lack of preservation very often resulting in their partial or even complete destruction. The progressive degradation of buildings is mainly due to human negligence, the lack of effective and continuous renovation. A method has been developed to determine the order in which the necessary renovation work to save the building should be carried out. The problem of neglected renovation was presented using the example of the palace building in Studzieniec. The building was constructed in the 16th century, at that time it served a defensive function and, after reconstruction in 1786, a representative and residential function. During the Second World War and the liberation in 1945, the manor house survived intact, although the interiors were looted. No renovation was carried out after the Second World War and this is the main reason for the degradation of the building.

Beata Nowogońska
Education in Assessment and Retrofitting of Historical Timber Structures: Integration of Teaching and Practice

The paper deals with the specific approach to teach the subject of assessment and retrofitting of historical timber structures to students of various colleges in an integrated and multidisciplinary course. Timber structures belong to the oldest structures in the world and because of their specific susceptibility to ageing, often require a profound analysis with respect to their current state and functionality. Especially in Europe, city centres are full of historical buildings that present an important cultural heritage, and as a consequence have a protected status. This status entails that these structures need to be assessed, maintained and monitored carefully, to keep the state of these structures at a level that they can perform. These tasks are often complicated and require interdisciplinary work. In education, this interdisciplinarity is often difficult to incorporate in the curriculum, as various expertises needed for cultural heritage assessment are separately and often fragmentary present at various colleges or faculties of universities, if present at all. Also, different teaching approaches may hinder course development. This paper deals with educational activities that have been developed and experienced at TU Munich and TU Delft, along with the cooperation with the University of Zagreb, dealing with the most important aspects of the assessment and analysis of historical timber structures.

J. W. G. van de Kuilen, W. F. Gard, H. Turkulin
Historical Wooden Pile Foundations in Amsterdam: An Integrated Approach for the Estimation of Structural Performance and Residual Service Life

Timber pile foundations are widespread in many areas around Europe and North-America. Especially in areas with weak soils, timber pile foundations have been a very good and economic solution. That foundations can be up to 500 years in service in cities like Venice, Amsterdam, Boston and many others. Degradation of the piles may occur over time which may influence considerably the residual service life. Residual service life is depending both on the time-to-failure behavior of wood, as well as the dead and live loads on the piles below buildings, quay walls and bridges. A good assessment method is required, as closing down infrastructure (bridges, quays) or buildings because of failing foundations causes considerable economical damage. In recent years in the cities of Rotterdam and Amsterdam failures occurs on such foundations. A comprehensive research program has been set up, that includes the development of underwater microdrilling equipment, so that an indication of the wood quality can be done in situ, without the need of bringing samples to the laboratory. The development of this microdrilling has been paired with a large scale campaign to determine the strength of new and recovered piles. In a next step, by applying a non-linear damage accumulation model, the remaining service life is estimated as a function of the decay level and decay rate, as well as the expected mechanical loads.

Wolfgang Gard, Geert Ravenshorst, Jan-Willem van de Kuilen
Bait Mohammed Bin Khalifa, the Challenging Consolidation of an Emirati “Transition Period” Building

Built in 1958 in Al Ain, the house of Sheikh Mohammed bin Khalifa is a significant building in the context of the UAE’s recent history, as it represents tangible evidence of a period of economic, social and cultural transition between the pre-oil and post-oil eras. A conservation project was initiated in 2013 by the Department of Culture and Tourism – Abu Dhabi, which envisioned reinstating the site as a cultural and social hub for the Al Ain community, commemorating the memory of the late Sheikh Mohammed bin Khalifa who was a significant local figure as well as celebrating the house as one of the few surviving examples of a “transitional” architectural style where traditional and modern building materials, techniques and design were experimented with. The conservation of the building aimed to strike a balance between preserving the tangible and intangible significant values of the house while adapting the site to create a vibrant community center. The project was completed in 2021.The following article will present the character-defining construction characteristics of this mid-20th century architectural heritage, the building’s pathologies as a result of the experimental use and hybridisation of materials and techniques characteristic of the ‘transitional style’. Finally, the article will also present the repair and reinforcement strategies and techniques implemented to preserve a tangible testimony to the complexity of this historical period.

P. Barucco, A. Chabbi, A. Mordanova
San Fermo Monastery in Verona, Italy: Studies and Vulnerability Analysis of a Post 2ndWW Reconstruction

The complex of the former San Fermo Maggiore in Verona is a system of contiguous cloisters.The first monastic nucleus on the banks of the Adige River is linked to the Benedictine presence probably from 996. With the transformations made by the Franciscan Minors starting from 1261, the monastic settlement expanded. The transformation of the Convent for the inclusion of government offices begins in 1807 and it lasted in several phases until 1937.During the II World War the complex was heavily damaged by bombing. The reconstruction took place in many lots and lasted until the 1970s. After that, other modifications occurred to adapt to the needs of the new use as Verona Superintendency headquarters.The article presents a study campaign on post-war interventions, carried out on the site documentation available in the city archives. At least 13 lots were realized: all the accounting documents were analyzed. After that, the information obtained from the documents had been verified on the building with on-site inspections and small assays. Geometrical laser scanner survey and structural surveys were carried on. All the results were used to define the structures diagnostic campaign. Particular attention was paid to the study of the insertion of reinforced concrete frames inside the original stone masonry structure.The study revealed that traditional construction techniques have remained in common practice during the 30-year reconstruction, and they have adapted to the introduction of new cement-based materials.Finally, structural analysis was carried on with results obtained from the above studies.

Elena Manzoni, Silvia Dandria, Massimo Donisi, Emilio Costanzo
Management of Information Workflows in HBIM Processes for Structural Analysis: Interoperability and Open Exchange Formats

The current AECO sector is heavily reliant on the adoption of proprietary software that limits the sharing and use of information among the various players in the supply chain. But interoperability is one of the pillars on which the new BIM methodology is based and is also one of the cornerstones from the international buildingSMART association, which promotes the use of a standard language that can increase efficiency and information exchange throughout the building process. The present study aims to investigate the issue of interoperability between software in the context of openBIM methodologies applied to the structural analysis of historic architecture built using traditional constructive techniques. The experimentation was conducted using the open-source software Code_Aster, based on the finite element method (FEM) of calculation, to which must be added the graphical interface Salome-Meca, offering together an integrated working platform. The reported case study is related to the Romanesque Church of Santa Giusta, in the Campidano region of Simaxis in Sardinia. The historic building was modeled through a Scan-to-BIM process using Autodesk’s proprietary software, ReCap and Revit, then through Rhinoceros software and finally into the numerical solver via interoperable exchange formats. The research involved at first only some of the main elements of the structure such as the cross vaults, and then moved on to more complex “compound” elements, which required both ad hoc modeling-side simplification strategies and reworkings within the analysis software.

Carlo Biagini, Andrea Bongini, Ettore Di Costanzo
Gaps Between Principles and Practices in Heritage Strengthening: Assessment of a Conservation Project of a Japanese Monument

The paper discusses a recent conservation project of a heritage building in Japan. It was a brick masonry church. It has been designated as a Japanese important tangible cultural property. The project focused on seismic retrofitting. Taking this project as the case study, the present research is composed of three tasks. The first task outlines the principles of the conservation of monuments, referring to international charters and guidelines. Discussion is also made on approaches to the strengthening of heritage structures. Second, the case study was introduced with a focus on the seismic retrofitting. Third, the efficacy of the strengthening is evaluated by performing pushover analysis and nonlinear dynamic analysis (NDA). Numerical models were prepared by taking into account dynamic identification tests performed on the structures before and after strengthening. For the application of NDA, an accelerogram was generated from the 2016 Kumamoto earthquake (7.0 Mw) that occurred close to the church. The paper critically reviews a recent seismic retrofitting project and sheds the light on the issues of heritage strengthening for future successful conservation practices in seismic-prone regions.

Yohei Endo, Munetaka Uemoto
Digital Twins of Stone Masonry Buildings for Damage Assessment

Digital twins are virtual models of physical objects or systems that enable real-time monitoring and analysis. In the field of stone masonry buildings, digital twins can be used to assess damage, predict maintenance needs, and optimize building performance. However, creating and analyzing digital twins of stone masonry buildings can be a complex and time-consuming process that requires specialized skills and equipment. In this paper, we present various methodologies for the generation of damage augmented digital twins (DADTs) of stone masonry buildings that involve the use of machine learning and computer vision techniques to automate the process. These methodologies include crack segmentation using convolutional neural networks, crack characterization using machine learning, automatic generation of simplified geometries of buildings, generation of DADTs containing geometrical and damage information, generation of finite element models for stone masonry buildings, and geometrical digital twins for stone masonry elements for numerical modeling. We demonstrate the effectiveness of these methodologies using a variety of datasets and show that they can significantly improve the accuracy and speed of damage assessment compared to traditional methods. Our work contributes to the development of a framework for real-time damage assessment of stone masonry buildings and lays the foundation for future research in this area.

Bryan German Pantoja-Rosero, Radhakrishna Achanta, Katrin Beyer
Structural Analysis of Historical Constructions
herausgegeben von
Yohei Endo
Toshikazu Hanazato
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