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2023 | Buch

Testing and Experimentation in Civil Engineering

From Current to Smart Technologies

herausgegeben von: Carlos Chastre, José Neves, Diogo Ribeiro, Fernando F. S. Pinho, Hugo Biscaia, Maria Graça Neves, Paulina Faria, Rui Micaelo

Verlag: Springer Nature Switzerland

Buchreihe : RILEM Bookseries


Über dieses Buch

This book gathers the peer-reviewed selected papers presented at the 3rd International Conference on Testing and Experimentation in Civil Engineering (TEST&E 2022), held in Almada, Portugal, on June 21-23, 2022. It showcases the role of smart technologies in all civil engineering areas, such as structures and construction, geotechnics and natural resources, hydraulics and water resources, transportation and communication networks. The conference topics encompass big data and advanced data processing systems, AI applications, virtual and augmented reality, 3D modeling and printing, digital twins, automation, sensing and detection technologies, inspection, monitoring and automatic damage identification, destructive and non-destructive testing, bio, nano and new materials, disaster risk reduction and emergency management. As such the book represents an invaluable, up-to-the-minute tool, and offers an important platform to engineers and architects.



3D Modelling and Printing

Use of Automated Control Machining Tools for Design, Construction, and Testing with Hydraulic Physical Models

To the present day, hydraulic physical models are essential for hydraulic structures design validation and optimization. ‘Traditional’ modeling methods for hydraulic physical experimentation present some limitations and challenges. These have been overcome and dealt with at LNEC by adopting new constructive technologies and innovative automation methods, such as 3D printing, CNC cutting, and automatic measurement systems. These new technologies reduce the time needed to perform studies by increasing the ability for faster building, making easier any modifications of model components, and reducing construction waste upon model demolition. This work presents different studies performed at LNEC where 3D printed and CNC cut pieces were used: two 3D print pieces used in a spillway model; a large-scale 3D print of a scaled failing dam; a large head orifice spillway reproduced using CNC machining; and an entire physical model constructed fully based on new building technologies. These ‘Novel’ constructive technologies evidenced that they fulfill the needs of physical model studies, ensuring adequate structural behavior and appropriately reproducing the flow conditions.

António Muralha, Sílvia Amaral, Nuno Aido, Ricardo Jónatas, Solange Mendes, José F. Melo, Teresa Viseu
3D Modelling and Printing for the Design of the Wooden Structure of the Church of San Martín de Plasencia, Spain

This paper exposes the methodology with 3D modelling and 3D printing for the design of the wooden structure of the church of San Martín in Plasencia, which is rebuilt after a fire. This experimental method provides advantages both to document and to be able to recover the correct architectural form in wooden structures of the historical heritage, as well as for the structural check and construction of the wooden assemblies.

José-Carlos Salcedo

Biomaterials, Nanomaterials, and New Materials

Thermal Properties of Polymer Adhesive Modified with TiO2 Used for Structural Strengthening

The study presents the results of thermal analysis of epoxy resin coating modified with titanium dioxide obtained using differential scanning calorimetry. The analysis shows an improvement in the glass transition temperature of modified specimens.

Kamil Krzywiński, Carlos Chastre, Katarzyna Fedoruk, Adam Sieradzki, Łukasz Sadowski
Production and Characterization of Polymeric Capsules Containing Rejuvenators for Asphalt Mixtures Self-healing Purposes

Pavement distresses are a result of loading and natural ageing, though asphalt mixtures have self-healing capacity because the asphalt binder is a self-healing material. It has been demonstrated before that the asphalt binder drains to the cracks, closing it, if sufficient time and adequate temperature conditions are given. In practice, this mechanism is highly inefficient because traffic is not interrupted, and in-service temperatures are not high enough. Self-healing can be accelerated with capsules containing rejuvenators. The released rejuvenator modifies locally the rheology of the binder to drain faster to the crack. This paper investigates the effect of fabrication conditions of polymeric capsules, containing sunflower oil, to the morphological, geometrical, thermal, and mechanical characteristics of capsules. Capsules were produced by ionotropic gelation of sodium alginate and calcium chloride, using extrusion and air-atomization methods. The effect of supplementary high temperature conditioning and cross-linking with glutaraldehyde were investigated. The results showed that the amount of oil encapsulated in capsules depends on the sodium alginate and calcium chloride concentrations. Thus, these concentration values affect the size and mechanical properties of capsules. The mechanical strength increases substantially with the supplementary treatment. Finally, the capsules showed to significantly improve the self-healing ability of bituminous mastic beams.

Rui Micaelo, Andreia Caeiro, Luís Baltazar, João P. Borges
A Review of Laboratory Tests to Evaluate Agro-Industrial Wastes Properties as Building Materials

The current research trend is finding out feasible solutions to guarantee sustainable building practices. Among the studied possibilities, the production of eco-friendly materials is widely investigated. To propose efficient building products the proper evaluation of their properties is extremely important. The present work considers some laboratory tests to analyse building materials, focusing on agro-industrial wastes (bio-wastes of floriculture and forest management, agricultural practices and agro-industrial processes). It considers hygrothermal performance and biological susceptibility of agro-industrial wastes both individually and in composites. Several past studies addressed this topic by using different laboratory tests and mainly considering composites. Although bio-susceptibility is one of the main drawbacks of bio-based building materials, it is not so commonly assessed. However, many laboratory tests can be carried out, due to the different bio agents and critical conditions. The present work aims at collecting this information to give a summarised list of methods that could be a simplified starting point to study agro-industrial wastes and agro-industrial waste-based composites for building practices.

Eleonora Cintura, Lina Nunes, Paulina Faria
Geotechnical Characterization of Vegetal Biomass Ashes Based Materials for Liner Production

This paper aims to evaluate geotechnically, chemically, mechanically, and hydraulically parameters of vegetal-based biomass ashes (VBA) and its soil incorporation with different ratios as potential liner material and soils strengthening. Composites were developed for testing with different ratios of VBA: soil, following 05:95, 10:90, 15:85, and 20:80%. All laboratorial testing program followed European standards. For geotechnical characterization, the following tests were performed for all mixtures, the soil and VBA: granulometric distribution, specific gravity and Atterberg limits. Chemical characterization was done by collecting pH values and energy-dispersive X-ray spectroscopy (EDS) parameters for elemental and oxides analysis. Also, x-ray diffraction (XRD) was done to evaluate all sample’s mineralogical description. In addition, mechanical analysis was conducted by analyzing expansibility, one-dimension consolidation through oedometer, and consolidated undrained (CU) triaxial test, along with falling head permeability for additional permeability analysis. Results have shown a finer granulometry and decrease of plasticity, 5% to non-plastic behavior, as higher amounts of VBA are introduced, exposing a filling-material behavior. EDS and XRD analysis indicate quartz, muscovite, orthoclase and calcite composition, and VBA could possibly have pozzolanic properties due to high silica-alum-ferric oxides amount. Mechanical parameters have shown a stabilization of VBA within the analyzed soil, exposing a slight reduction on settlements while increasing friction angle, 25–30º, and decreasing cohesion, 5–0 kPa. Permeability values have shown their feasibility for liners application, as found values characterizes all mixtures as low-permeability materials, especially introducing 5% of the residue into soil which values were below 10–9 m/s. Thus, the incorporation of VBA into soils paves a solid alternative for reusing this material in varied applications, as the analyzed soft soil has been geotechnically enhanced. Additional analysis, mainly pozzolanicity levels and leachability tests, can contribute for this on-going study to stablish VBA as a feasible material for the industry.

Leonardo Marchiori, Andre Studart, Maria Vitoria Morais, António Albuquerque, Victor Cavaleiro
An Input in the Asian Wasp Nest (AWN) Study

The Asian Wasp Nest (AWN) is an impressive and robust natural construction built by an insect. The building process occurs during spring and summer. This type of nest is not reused. The scale size between the Asian wasp and the AWN is substantial. In Portugal, we can find AWN on trees, roofs, balconies, chimneys, and other possibilities. When the AWN is built on trees, the tree's branches work as support. The complexity of this natural construction in terms of shape motivated this research work. Therefore, an AWN sample was used in order to obtain some information concerning this technical aspect. In this context, X-ray tests were performed to give guidance about the internal structure of the AWN without damaging it. The obtained experimental results show the richness of this type of construction. Understating the AWN may guide new building processes, different structural shapes, alternative natural building materials, and passive building technics, among other constructive fields.

Jorge Pinto, Mário Ginja, Miguel Nepomuceno, Sandra Pereira

Destructive and Non-destructive Testing

Moisture Buffering Value of Plasters: The Influence of Two Different Test Methods

The moisture buffering value (MBV) is considered nowadays an easy way to classify building materials when the purpose is assessing their potential passive contribution to indoor comfort and energy saving. In literature different test methods, and relative MBVs calculated on the basis of these, are found. Hence, a study was conducted to confirm the comparability of results. Eight different plastering mortars and finishing pastes underwent the two most common test methods—the ISO 24353 and the NORDTEST protocol—and the related MBVs were calculated. It was observed that the MBV is different when different test methods are followed, although results are proportional. The values obtained following the NORDTEST method are found always higher that the values obtained following the ISO 24353 and, therefore, it is concluded that MBV is affected by the test procedures and can only be directly compared when the same procedure is used.

Alessandra Ranesi, Paulina Faria, Rosário Veiga
Study on the Effect of the Bedding Mortar Composition on the Shear and Compression Behavior of Old Brick Masonry Walls

The aim of this study was to investigate the influence of the bedding mortar characteristics on the shear and compression behavior of brick masonry walls typical of old buildings. For this purpose, two different mortar compositions were considered, namely a cement mortar and a lime-cement mortar with composition ratios of 1:0:5 and 1:3:12 (ce-ment:hydrated lime:sand), respectively. The initial part of the study consisted of experimentally determining the main mortars’ characteristics. Then, their effect on the shear and compression behavior of solid clay brick masonry was experimentally assessed. For this purpose, di-agonal compression tests and axial compression tests were performed on masonry specimens made with both types of bedding mortars. The results show that the mortar characteristics have a significant influence both on the shear and compressive behavior. The average shear strength values of the cement mortar walls were six times higher than that of the cement-lime mortar walls. The average compressive strength values of the cement mortar walls were two times higher than that of the cement-lime mortar walls. This shows that the mortar characteristics have a greater influence on the shear behavior when com-pared to compressive behavior.

Armando Demaj, Ana I. Marques, João Gomes Ferreira, António Sousa Gago
New Methodology for Rocks’ Geomechanical Characterization with Schmidt Sclerometer

Hardness is a parameter that gives information about the behavior of rocks when subjected to certain deformations. Various non-destructive tests are available for hardness quantification, the use of the Schmidt Sclerometer is the most used due its expedition, among existing sclerometers, the Schmidt rebound hammer, type N-34, with an impact energy equal to 2,207 N.m (0.225 Kgm) was selected for experimental tests. Schmidt's hardness index (R) obtained were related to other physical parameters of the rock, namely uniaxial compressive strength (UCS), elasticity modulus (Ɛ), specific gravity and granularity. For comparison purpose, several literature’s methodologies are present focused on improving procedures and developing correlations for different rock types. In this sense, to assess the methodology that best suits granitic rocks’ characterization, several laboratorial and “in situ” tests from the literature were performed. Additionally, the paper proposes a new methodology based on the analysis of the results and a good relation between R and UCS parameters, concluding reliability on the methodology for values of non-porphyroid granitic rocks, predominantly biotitic and from medium to fine granularity, in a precise and consistent way.

Victor Cavaleiro, Leonardo Marchiori, Maria Vitoria Morais, Gabriel Marchi, Marcela Cocchiarale
Experimental Analysis of Traditional Stone Masonry Walls Under Blast Loadings

This paper presents results obtained in a MSc thesis (1st author) developed in NOVA School of Science and Technology (FCT NOVA) (Joaquim, in Behaviour of traditional stone masonry walls subjected to blast loading. Master Thesis, Civil Engineering. FCT NOVA, Lisbon, 2021) regarding the blast behavior of traditional stone masonry walls. In order to understand this phenomenon, two types of tests were performed, using two traditional stone masonry specimens (M1 and M2) with dimensions 1.20 m × 1.20 m × 0.40 m (length × width × thickness), produced by Pinho (Ordinary masonry walls—Experimental study with unstrengthened and strengthened specimens. Ph.D Thesis, Civil Engineering. FCT NOVA, Lisbon, 17/out/07, 2007). Firstly, the specimens (walls) were subjected to unconfined explosions—without physical barriers between the explosion and the target/wall. Secondly, after the explosions, the axial compressive strengths of the two walls were evaluated. In this paper, the results and discussion of the first kind of tests are presented.

Bruno Joaquim, João Conceição, Fernando F. S. Pinho
Dynamic Behavior of a Two-Storey Cross Laminated Timber Mockup

Timber constructions have gained an increasing attention in the last years, due to the limited installation time and the reduced expertise in manpower required, since panels assemblage is mainly based on dry mounting techniques. Among these, Cross Laminated Timber (CLT) products are extensively used in constructions, as they allow to overcome the main weaknesses of hardwood artifacts. Moreover, CLT components are also being tested within the restoration and re-use of existing buildings. Since these timber products are relatively new in the construction market, experimental data and site investigations are still limited and some aspects still unknown. Among the many, dynamic characterization of CLT structures, and related model updating, is rare in literature. In such a context, an experimental campaign aimed at assessing the linear dynamic behavior of CLT structures was carried out. A building-scale specimen (mockup) was constructed; it was made of C24 CLT walls and diaphragms (floor and roof) with 10- and 14-cm thick panels, respectively, connected through steel brackets and screws. The mockup was investigated via dynamic identification tests, by implementing 12 piezoelectric accelerometers, i.e., 4 on the first floor and 8 on the roof. The experimental characterization was aimed at: (i) assessing the structural dynamic behavior and identifying the role of structural details on it; (ii) evaluating the experimental stiffness, compared to analytical predictions. At last, a finite element (FE) model was implemented and updated based on the experimental outcomes.

Matteo Salvalaggio, Filippo Lorenzoni, Maria Rosa Valluzzi
Shear Capacity Assessment of Steel-To-CLT Connectors

In modern prefabricated wooden buildings, CLT elements (Cross Laminated Timber, also known as Xlam, CrossLam or BSP) are assembled into macro elements (e.g., walls and slabs) and anchored by means of steel brackets and fasteners. A wide variety of such elements, in the shape of nails, screws and bolts, has been used in the construction market in recent years. Both the novelty of the construction technique and the wide number of fastener types imply that the knowledge about timber (CLT) joints is still limited. Under seismic shocks, steel-to-timber joints can prevent timber panels from overturning but, due to their high stiffness and low ductility, seismic energy dissipation occurs by damaging the timber elements over the fastening area. Hence, the sizing of such joints is a key factor in the design of a timber building. To improve the knowledge on the behavior of fastened steel-to-timber joints an experimental campaign was carried out. The paper discusses the testing of steel-to-CLT specimens, at changing of fasteners (i) type (i.e., 60 mm-length Anker nails and screws) and (ii) number (i.e., 2, 10, 18). The research aimed at characterizing the strength and stiffness of the compound element and at estimating the potential redistribution of loads at increasing number of fasteners (i.e., group effect).

Matteo Salvalaggio, Enrico Garbin, Maria Rosa Valluzzi
Test Procedures for the Characterization of Earth Plastering Mortars: Necessary Adaptations

Earth mortars present advantages, especially when applied to plasters. To evaluate the behavior of earth plastering mortars, some adaptations can be made to the test procedures defined for current mortars—capillary absorption and drying—or earth blocks—water erosion by dripping action. However, specific tests for earth mortars—linear shrinkage and cracking, dry abrasion resistance, adsorption and desorption by hygroscopicity—can also be applied to evaluate the behavior of current mortars. It is considered important to assess the surface cohesion of earth plasters, as to current mortar plasters. In this way, it is possible to complement the characterization and, thus, be able to make a more efficient comparison between current and earth plastering mortars, depending on the intended applications. The type of specimens—with or without the influence of the substrate—as well as their dimensions, may also influence the correct analysis of the characteristics of the mortar samples produced in the laboratory, exposed in situ or extracted from case studies.

Tânia Santos, Paulina Faria
Large Static Testing Equipment: Design and Testing of a Settlement Facility

Masonry structures are highly vulnerable to climate change effects. In particular, over the last few decades, the effects of global warming have caused wetter winters and drier summers. Such phenomenon has produced variations in soil saturation that, in the long term, may trigger consolidation-induced differential settlements. Therefore, the experimental replication of settlement actions is essential for developing appropriate numerical tools and understanding their consequences on masonry structures. This paper describes the installation of a 1.5 × 1m2 settlement table at the University of Minho. Practical issues and first tests on masonry shear walls are also discussed.

Nathanaël Savalle, Marco Francesco Funari, Luciano Fernandes, Carla Colombo, Simon Szabó, Sajad Hussaini, Shaghayegh Karimzadeh, Paulo B. Lourenço
A Discussion on the Determination of Permeability and Absorption in Concrete

Periodic and non-routine inspections on buildings, infrastructures, and sites of historical or architectural interest frequently involve a necessary deepening of the knowledge of natural or artificial stone materials. The quality and functional performance, the state of conservation, and possible pathologies of stone materials of structures and building envelopes, as a norm, have to be evaluated by performing tests and samplings with a minimal degree of invasiveness. This last requirement, aiming at the limit of nondestructive testing, stems from the necessity to find a balance among preservation of structural, historical, and artistic integrity of the inspected stone materials, an acceptable level of gained knowledge on the built element, and sufficient reliability of the deployed diagnostic activities. While the requirement of least invasiveness is common to many inspective and diagnostic practices belonging to different technical sciences, such as structural engineering, architecture, and restoration, as well known, however, the conditions of minimum knowledge gain and minimum acceptable reliability can be seldom granted by methods of testing that are completely nondestructive. The last century of investigations has shown the pivotal role of permeability for durability assessment of building stones and concrete, with the possibility of reducing invasiveness by using smaller stone samples in uniaxial water-permeation tests. This contribution presents a review on past and present experimental methods for determining permeability in concrete, some of which are also applicable to other porous building materials, with a discussion on optimality criteria for testing and sampling which is carried out in the light of an historical perspective and of a view towards the Life Cycle Assessment of interventions on the built heritage.

Michela Monaco, Roberto Serpieri, Mariateresa Guadagnuolo, Giorgio Frunzio
Physical Methods and Scanning Electron Microscopy for Evaluation of Bioclogging in Geotextiles

Wastewater induced biological clogging (or bioclogging) is a common mechanism in geotextiles used in several applications in environmental sanitation and environmental geotechnics works, such as earth-based wastewater treatment plants, earth ponds for mining residues and sanitary landfills. Permeability tests or weighing experiments are currently used for detecting physical clogging but are unable to detect the evolution of clogging caused by microbiological activity (bioclogging). The association of tracer tests, complemented with scanning electron microscopy (SEM) and weighting experiments would be an advance for the understanding and evaluation of bioclogging. Understanding how the biological parameters behave in a restricted way, without interference from physical and chemical parameters, could help in the definition of measures to avoid the problem and increase geotextiles lifespan. Preliminary experiments carried out in Petri dishes with non-woven geotextile and domestic wastewater showed a quick adhesion and growth of biofilm in this material, allowing the development of a laboratory setup for bioclogging tests in porous materials.

Maria Vitoria Morais, Leonardo Marchiori, António Albuquerque, Victor Cavaleiro
A Comparative Experimental Campaign to Estimate the Normal Interface Stiffness of Dry-Joint Masonry Structures

Dry-joint masonry structures are particularly vulnerable to earthquakes and their dynamic response strongly depends on the interaction between units. Therefore, the precise characterisation of their behaviour is of paramount importance. This study performs an experimental campaign to estimate the normal interface stiffness of dry-joint masonry specimens. Owing to the lack of standardised experimental procedures, two experimental methods are herein presented, namely deformation-based and vibration-based. Despite their fundamental differences, the results reveal very good agreement between the methods, which, in turn, capture well the marked non-linear dependency between the normal stress and the normal interface stiffness. Importantly, the outcomes of the present study also serve as a validation framework between the two methods, providing confidence for their independent or concurrent use.

Carla Colombo, Georgios Vlachakis, Nathanaёl Savalle, Anastasios I. Giouvanidis, Luciano Fernandes, Christiam C. Angel, Federica Vadalà, Paulo B. Lourenço
Thermal Properties of Polymer Floor Coating with Alternative Granite Powder Filler

The study presents the results of the thermal analysis of epoxy resin coating and waste granite powder as an alternative filler to quartz sand. For thermal analysis, differential scanning calorimetry and dilatometry method was used. The results show that adding granite powder to epoxy resin does not change glass transition temperature. It only reduces the specific heat capacity of the composite.

Kamil Krzywiński, Łukasz Sadowski, Katarzyna Fedoruk, Adam Sieradzki
Absorption Tests of Binary and Ternary Mortar Mixtures and Their Relationship with Compressive Strength

As the environmental and circular economy issues have become one of the most important worldwide matters, the researchers have focused on reducing the carbon footprint of all kinds of cementitious materials. One of the most effective ways to reduce CO2 emissions is the partial substitution of cement with mineral admixtures in concrete and mortars without jeopardizing their mechanical and durability properties. The positive impact on the environment is especially relevant when those mineral admixtures come from industrial byproducts. However, international standards do not offer sufficient guidelines to characterize mortar mixtures that incorporate byproducts as mineral admixtures. Nonetheless, some of those waste mineral admixtures allow for improving properties, such as capillary absorption and mechanical performance in mixtures. The method proposed in this research allows establishing the absorption capacity of the mortar through an experimental setup based on the porosity of the specimens. This research found a relationship between absorption and compressive strength, validating the inverse relationship between both properties and preparing the path for new standardizations for the mineral admixtures used.

Nemesio Daza, Yoleimy Ávila, Andrés Guzmán, Joaquín Abellán-Garcia
Precision of Test Methods for Hot Mix Asphalt

The paper presents the Portuguese experience in the precision evaluation of test methods for hot mix asphalt (AC 14 surf and AC 20 base). The repeatability and reproducibility values were determined based on Proficiency Test Schemes involving several laboratories. The tests were performed from 2007 until 2021. The paper analyses the soluble binder content, maximum density (Method A), bulk density (Procedure B), and Marshall properties (stability and flow). The results were compared with the European standards’ precision data. The analysis confirmed a wide variation of the precision data. Precision was not always constant, but, in some cases, it did seem to be influenced by the characteristics of the bituminous mixture, contrary to the variation presented in the test standards. In general, a lower reproducibility was observed.

José Neves, Cláudia Silva, Ana Duarte
Assessment of Mechanical and Physical Behaviour of Sandstones Through Quasi Non-destructive Tests

An experimental programme was carried out in order to assess physical properties, such as porosity and mechanical behaviour, through compression and drilling strength of sandstones, classified as lithic arkose. These stones are similar to those found on St. Leonard’s church at Atouguia da Baleia village in the Western region of Portugal. This monument’s façades were selected because of the extent and depth of the most important degradation pattern exhibited, the alveolization. The Drilling Resistance Measurement Test is an important way to survey the extent of stone weathering on historical building stones due to the correlation of porosity and compressive strength with the drilling strength parameter. It is also a less intrusive and quasi-non-destructive portable test. The drilling time is even lower than other tests duration for lower porosity materials. Absolute differences between experimental and predicted values of porosity obtained on these sandstones through correlations with drilling strength are in general lower than 13%. Considering the best correlation, these absolute differences are up to 6%.

Marco Ludovico-Marques, Carlos Chastre

Inspection, Monitoring, and Automatic Damage Identification

Design and Construction of a Test Setup to Investigate Ground Settlement Response of Large-Scale Masonry Building Models

Underground construction activities such as tunnelling and deep excavations in urban areas may impact a significant number of surface structures and cause damage. Tunnelling-induced damage can often be repaired, but at great expense, due to significant repair costs and associated project delays. Within this context, damage caused by excavation-induced ground movements on heritage masonry buildings requires further attention, due to the cultural value and vulnerability of these assets. There is a need for experimental studies to better understand the structural response of these buildings to excavation-induced ground movements. In this study, a test setup was designed and constructed to examine the response of an experimental building model, replicating historic masonry structures, against differential settlement effects. The settlement apparatus relies on controlled jacking of large steel beams to apply differential displacements to the building. A specific tunneling scenario was considered for the design of the settlement apparatus. The constructed test setup is validated by evaluating the displacement profiles of the steel beam for different tests, with or without building. Differences between the differential settlements experienced by the steel beam and the building highlights how building weight and progressive damage may increase compliance to ground movements.

Korhan Deniz Dalgic, Cennet Yesilyurt, Burcu Gulen, Yiyan Liu, Sinan Acikgoz, Muhammed Marasli, Alper Ilki
Metrological Characterization and Traceability of the Strain Column Measurement Standard

This paper describes the development of experimental methods for the metrological characterization and traceability of an in house produced strain column measurement standard, for use in hardened concrete compression machine testing. The performed characterization included the determination of dimensional (diameter, height) and geometrical quantities (flatness, shape, parallelism, perpendicularity, circularity and cylindricity) using a three-dimensional coordinate measuring machine, and the evaluation of the strain measurement accuracy and uniformity. Traceability to the International System of Units (SI) was achieved by calibration using a laser interferometer. The obtained estimates and measurement uncertainties supported its conformity assessment, considering the applicable EN 12390-4 normative tolerances and adopted decision rule (hypothesis test, without guard bands, assuming a type I error of 1% and a Gaussian probability density function). This work allowed concluding that the produced strain column complies with all the normative technical requirements and can be used in the metrological testing of hardened concrete compression machines.

Luís Martins, Ricardo Mendes, Alexandre Pinheiro, Álvaro Ribeiro
Experimental Design for Building Retrofit Studies: The Assessment of the Thermal Behaviour of a Solar Passive Retrofit Solution

Most of Portuguese residential building stock is obsolete in terms of thermal comfort and, as a result, they have poor energy performance. One of the main reasons for the poor performance are structural thermal bridges on façades, which are areas where thermal energy is significantly lost during the heating season. To solve this problem, a novel approach of the Trombe wall system, named Solar Bridge Retrofit Solution (SBRS), was proposed. This paper presents the experimental measuring procedure designed to assess the thermal behaviour of the SBRS, during the heating and cooling season. Several experimental results are also presented and analysed.

Sara Brito-Coimbra, Daniel Aelenei, Maria Glória Gomes, António Moret Rodrigues
Condition Assessment of a Metallic Runway Beam Based on Dynamic and Static Testing

This work describes the experimental evaluation of the structural condition of a metallic runway beam located in a heavy industry facility. The study involved carrying out an ambient vibration test, aiming the identification of the modal parameters of the beam, in addition to a static test under the action of a transportation vehicle carrying heavy raw material. The static test was mainly focused on the measurement of deformations and displacements on critical sections of the beam. The results of both tests will be useful for the experimental calibration of the numerical model of the beam developed by the designers, which will provide support for the structural rehabilitation and strengthening of the runway beam.

Diogo Ribeiro, Cristina Alves Ribeiro, Jorge Leite, Cássio Bragança, Manuel Silva, Nuno Pinto, Pedro Conceição, António Gaspar

Modelling and Validation of Models

Numerical Simulation of RC Beams Strengthened by Post-tensioning

In the present paper, a numerical simulation performed in the structural analysis framework OpenSeesPy (Python interpreter for OpenSees) of post-tensioned strengthening solutions for RC beams in frame systems, proposed by Gião and Muhaj, is presented. Two reference specimens (VR2 and CB1) and three strengthened specimens were evaluated—one specimen strengthened with non-adherent exterior post-tensioning strands (VPE) and the other two specimens strengthened with interior post-tensioning strands with anchorages by bonding (CB2 and CB3). The two strengthened solutions under analysis aimed to improve the hysteretic behaviour of the beams and, if the techniques are applied to frames, avoid the development of unidirectional plastic hinges. The models were loaded simultaneously with cyclic horizontal displacements and significant gravity loads. The numeric results are analysed and validated by comparison with the experimental ones. The strengthened solutions displayed greater energy dissipation and minor residual deformations than the reference specimens, showing to be adequate seismic strengthening techniques.

Márcia Duarte, Carla Marchão, Rita Gião
Accident Prediction Model Applied to Motorway A29 in Portugal

Road accidents are still one of the biggest public health problems in the world, and research must be stepped up to tackle the issue. The present study describes the development of a statistical model for predicting accidents occurring on motorway segments over the period 2015–19. The case study comprises 218 tangents and curves, separately for either direction, of motorway A29 in Portugal, which is operated by Ascendi under a concession awarded by the Portuguese state. Exposure, geometric design variables, and annual trend were incorporated to the model, considering a negative binomial probability distribution, and a flexible function form allowing non-constant elasticity values was utilized. In addition to the exposure variables, the geometric design risk factors found to be significant were the horizontal curvature, and the presence of deceleration lane. A significant decreasing in accident annual trend was also observed. The fitted model was validated using cumulative residual plots. The results obtained allowed the prediction of accident frequency as well as the identification of the design risk factors.

Sara Ferreira, António Couto, António Lobo, Suellen Souza, César De Santos-Berbel, João Neves
Numerical Modeling of Reinforced Concrete T-Beams

ATENA Engineering 3D software was used to build various numerical models of a RC specimen that was tested in the Laboratory of Heavy Structures of NOVA School of Science and Technology. Specimen CB0 was the reference one of a broader experimental campaign. The sensitivity analysis was carried out after the experimental campaign, aiming to understand better the influence of different factors, such as the FE type and size, and the fracture energy. The obtained results were compared with the experimental results of beam CB0. The behaviour of the numerical model built with 40 mm quadrilateral FE was found to be the most appropriate one.

Helisa Muhaj, Carla Marchão, Válter Lúcio, Rita Gião

New Sensors and Technologies

Estimation of River Flow Discharges Using Image Processing

In the scope of water resources management, the regular measurement of river flow discharge is an essential tool to control and monitor natural variances and the prevention of damages in case of extreme events. The proposed method is based on Large-scale Image Velocimetry (LSPIV) i.e. on the analysis of a sequence of images and the measurement of the 2D velocity field at the surface of a watercourse. The present study consisted on the evaluation of this technique for the measurement of flow discharge based on experimental cases. The size and shape of the tracers and the relation between the depth-averaged and surface velocities were investigated by means of laboratory and in situ experiments. In addition, two LSPIV freeware software were tested and the quality of their results were analysed and compared to traditional measurements. The accuracy of the measurements seems to reach acceptable thresholds and the results were promising. Nevertheless, for a wider use of this technique, further research should be taken to solve specific issues.

Rodrigo Santos, João Nuno Fernandes
Damage Evolution in Physical Scale Model Tests of a Stretch of the Breakwater of Peniche Harbour

During physical scale model tests of rubble mound breakwaters, the assessment of the eroded volume of the armour layer subjected to incident sea waves can be determined from consecutive surveys of the surface of the armour layer after each test run. This enables one to assess the damage level of the structure by comparing erosion profiles and by the eroded volume between consecutive surveys of the tested section. The present study aimed to evaluate the damage evolution of a section of the Peniche harbour west breakwater, whose armour layer is made of tetrapods, A dimensionless damage parameter was computed, based on the eroded volume at the end of each test. The test program consisted of three test series (A, B and C) with different durations and wave conditions sequences, considering the low-water level (water depth of 0.20 m at the toe of the structure) and high-water level (0.24 m) and sea states with peak periods Tp = 1.70 s and Tp = 1.98 s and significant wave heights, Hm0, ranging between 0.12 m and 0.19 m. The model was built and operated according to Froude’s similarity law, with a geometrical scale of 1:50. The eroded volume assessment was done by means of armour layer surveys based on the Time of Flight (ToF) methodology, using a Kinect sensor position. The surveys produced 3D surface models, at the beginning and the end of the test series, when the whole extension of the armour layer was dry and visible, and after each intermediate test, when part of the armour layer was submerged. A comparative analysis was made, based upon the damage level obtained with the three different test series (with different durations and wave conditions sequences).

Rute Lemos, Conceição Fortes, João Alfredo Santos, Ana Mendonça
SfM Photogrammetry as a Tool to Monitor Slope Erosion and Evaluate Bio-Stabilization Treatment

Soil erosion in slopes mainly occurs due to runoff water. Biocementation may be an alternative to traditional stabilisation methods to prevent this phenomenon. In this research, enzyme induced calcium carbonate precipitation (EICP) was tested to analyse its efficiency in preventing soil erosion. To do so, two small slopes made of uniform-graded size sand were built in the laboratory and subjected to a water thread with constant flow to simulate runoff water. The first was the control test, untreated, while the second was treated by spraying with enzymes and feeding solution. The formation of ravines was monitored during and after the runoff test by using structure from Motion (SfM) photogrammetry. Image acquisition was performed with a mobile phone and a point cloud was generated to analyse the slopes surfaces and quantifying the amount of erosion on each slope. Finally, the percentage of carbonate precipitated in the enzymatically-treated slope was calculated after the end of the test.

Román Fernández Rodríguez, Rafaela Cardoso
An Open-Source 2D Digital Image Correlation Software: Case Study on the Hyperelastic Behaviour of Silicone-Based Material

Digital Image Correlation (DIC) is an optical-numerical method used to compute displacement and strain fields of target surfaces. This method has been widely implemented in the study of structures and to perform inspections, at several observation scales. Several software have been already proposed to carry out DIC measurements. In this study, a new integrated open-source DIC software is presented, so-called iCorrVision-2D. This DIC software includes a build-in grabber and post-processing modules that are not usually available on other open-source or commercial DIC software. The accuracy of this software is verified using an experimental dataset of silicone-based specimens subjected to uniaxial tensile test. The isotropic hyperelastic behaviour of the silicone-based specimens was investigated using the Neo-Hookean, Mooney-Rivlin, Lopez-Pamies, Ogden and Yeoh models. Results indicate that this software can be efficiently used to reconstruct the displacement and strain maps, yielding consistent mechanical properties for the hyperelastic material. This case study is important to illustrate the reliability of DIC on measuring deformations that have been used to extract relevant mechanical properties. This software can then be used consistently for other engineering applications.

João C. A D. Filho, Luiz C. S. Nunes, José Xavier
Point Fixed Tempered Laminated Glass Panels Subjected to Wind Load: Data Acquisition Through Electrical Strain Gauges/Displacement Transducers Versus Digital Image Correlation

In the context of the tempered laminated glass panels submitted to the wind’s action effect, such panels are commonly used in the construction of buildings’ facades, taking into account their notable resistance to mechanical actions while maintaining the characteristic of luminosity requested by the architectural options. This work approaches the characterisation of the structural behaviour of laminated glass panels punctually supported by bolts fixed on glass surface with structural adhesive. Each panel, fixed by means of 4 stainless steel articulated connectors, includes an EVASAFE® or PVB interlayer between the two foils of the laminated structural glass, being subjected to air pressure applied through the laboratory’s pressurised air system and controlled by means of a valve. The pressure value is obtained using a mechanically calibrated sensor connected to a specific software through a compatible datalogger. The data collected by the strain gauges/displacement transducers are compared with those provided by digital image correlation (DIC) equipment. The maximum stress is also calculated at the central point on each panel. The technology of instrumentation and data acquisition using digital image correlation presents advantages in terms of efficiency and reduction of error in experimental tests as long as the optical reliability is ensured, making it advantageous in the case of structural glass compared to the traditional methods for data acquisition. Four measurement points are displayed for the desired comparison. A good result between both technologies were obtained for displacements and strains on the critical points in that panels.

Afonso Mesquita, Eliana Inca, Cláudio Martins, Sandra Jordão
Image Analysis Techniques to Characterize Scaled Embankment Failures

The present work consists in the application of image analysis techniques to characterize the failure by overtopping of a scaled embankment dam that was experimentally tested in a medium-scale facility located at the National Laboratory of Civil Engineering. These techniques were used to describe the failure of the small-scale dam by defining the 3D profile of the dam body in several time instants. This was performed with depth images and with the characterization of the surface velocities of the flow near the breach based on the application of Particle Tracking Velocimetry (PTV) algorithm. The characterization of the 3D reconstruction of the failed dam and surface velocity maps in the breach vicinity were based on the post processing analysis of high-definition (HD) digital images and depth images, strategically acquired around the dam. This work assesses the usefulness of image analysis techniques for the applications herein presented.

Solange Mendes, Sílvia Amaral, Teresa Alvarez, Rui Aleixo, António Muralha, Teresa Viseu, Rui M. L. Ferreira
Monitoring the Madeira Airport Protection Breakwater Using Visual and Unmanned Aerial Vehicle Observations

An aerial monitoring system was developed for the maritime structures that protect the foundation columns of the Madeira Island Airport runway infrastructure, in the scope of the research project MEGE, to complement the already existing monitoring program of visual observations. For the aerial monitoring of the berm breakwater, with about 770 m in length, a fast data acquisition system was envisaged. Imaging techniques acquired through a high-resolution camera coupled to an unmanned aerial vehicle (UAV) were used, which allowed for a very fast and efficient automated procedure, compatible with the difficult accessibility to the structure on the seaside. Point clouds corresponding to the breakwater geometry were obtained from the set of aerial images from the camera on board of the UAV, using photogrammetric techniques. In this paper, the two complementary parts of the monitoring of this structure are described and some results are presented.

Rui Capitão, Maria Graça Neves, Pedro Sousa, António Cachaço, Francisco Barros, Paulo Tavares, Pedro Moreira, Conceição Fortes, Décio Rodrigues, Elsa Franco
Management and Monitoring of Civil Works Using Geographic Information Technology

As part of the operation and maintenance of road infrastructure, was developed a methodology based on mobile applications with ESRI technology to support the management and monitoring of civil works, capable of obtaining multimedia records on site and geographical visualization of work carried out in the field of road infrastructure maintenance. The typology of works presented in the article is of vegetation maintenance of slopes and the preparation phase of the respective works consists both in the collection of slopes with visual inspections, as well as in the risk analysis of slopes with high density of invasive species and trees near the road. With the creation of maps and registration applications adapted for each project (vegetation maintenance service), it is intended to provide the Contractors with real-time geographical orientation, and consequently, a greater operational performance. The intelligent registration and storage of information collected on site, the management platform, integration and validation of data and the production of reports aim to support decision-making in the context of the management of these projects. The methodology presented aims to carry out the progressive digital transition of the procedures previously used, optimizing with the use of geographic technology the efficiency of the management of the civil works.

Pedro Varela, Filipe Morais, José Sousa, Sara Sanches, Adriana Neves, Eliana Carreira, Alexandra Ferreira
Development of a Cohesive Model for CFRP-To-Steel Bonded Joints for Low and High Temperatures

This work analyses the impact of low and high temperatures on the bond between Carbon Fiber Reinforced Polymers (CFRP) and steel substrates. The aim of the experimental tests is to study the local and global bond behaviors of CFRP-to-steel joints under different temperature conditions. The results suggest that high temperatures are more severe for the joints than negative ones. Based on the experiments and on the data collected from the literature, a unified and updated cohesive model with temperature dependency is proposed.

Hugo Biscaia, Miguel Machado, Marta Carvalho, Telmo Santos, Yongming Yang
Automatic Classification of Facades Using Image Colour Differences

Non-invasive vision-based approaches provide the precision and reliability required for building facade inspection. A method based on automatic image classification to detect and map the materials and anomalies in building facades is presented and compared with a traditional visual inspection and classification.

Marta Torres-González, Jónatas Valença, Ana Silva, Maria P. Mendes
Wireless Sensors for Measuring Main Kinematic Parameters in Dynamic Tests Involving Intense Impacts

This study presents the development of two types of wireless sensor systems, one based on high-speed cameras and the other on high-capacity MEMS accelerometers. These sensors are intended for application in two experimental tests related to the ongoing SHELTER project aiming at developing a seismic shelter to protect human lives. In the first test, a half-scaled masonry building accommodating a half-scaled shelter on its top will be led to collapse over a shaking table for assessing the SHELTER impact accelerations during the building collapse. The second test type consists of free-fall of the SHELTER structure, supplied with a safety chair and a crash test dummy, to evaluate the shock accelerations on the human body. These damaging tests would not allow using the wired sensors often used in dynamic tests. Consequently, four wireless accelerometer sets containing two ±200 g accelerometers in the horizontal axes and one ±500 g accelerometer for the vertical direction were considered. In the building collapse test, these accelerometers will be installed in the half-scale shelter (four corners). In the free-fall tests, the accelerometers will be located in the shelter (three corners) and on the safety chair to hand out the large instant acceleration. Complementary measurements will be performed based on high-speed cameras and a large set of “optical + infrared” targets. These targets will be bonded to the under-studied model components in both tests. All sensors and targets were prepared and assembled in LNEC, where the shaking table test will be performed, and the sensor calibrations were carried out.

Seyedsajjad Hosseini, João Guerreiro, João Gomes Ferreira, Luís Guerreiro, Rita Moura
Testing and Experimentation in Civil Engineering
herausgegeben von
Carlos Chastre
José Neves
Diogo Ribeiro
Fernando F. S. Pinho
Hugo Biscaia
Maria Graça Neves
Paulina Faria
Rui Micaelo
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