Proceedings of Italian Concrete Days 2016

Currently climate and housing standards in parallel with the energy savings govern the performance required to buildings. Consequently, innovative multi-functional components try to satisfy both the requirements of structural safety and thermal performance, but the choice of the designer is difficult due to the complexity of this new market. In this paper, the Multi-Criteria Decision Making (MCDM) analysis is proposed as suitable methodology that can provide adequate support for choosing the best building components between different alternatives. As case study, TOPSIS method (Technique for Order Preference by Similarity to Ideal Solution) has been applied for comparing four different types of floor. The criteria assumed in the case study are referred to different fields as well as thermal, acoustic, air quality building science, structural performances, economic and human impacts. The case study allows to point out that the optimal solution depends on the importance (weight) that the decision maker assigns to each considered criterion.

The aim of the article is to describe the construction method and the difficulties encountered for the execution of an exceptional and unique work within the 3rd Bosphorus Bridge: the erection of the A-shaped towers. The erection of the A-shaped towers was a highly challenging activity due to their geometry and to the two different methods of construction: the slip forming system and an automatic climbing formwork system.

Nonlinear Finite Element Analysis (NLFEA) of the inelastic behaviour of RC walls are often carried out for uni-directional (in-plane) horizontal cyclic loading. In this paper the behaviour of RC walls with different cross-sections (T-shaped and U-shaped) subjected to bi-directional (in-plane and out-of-plane) loading is simulated by means of NLFEA. They are carried out with the software DIANA, using curved shell elements and a total strain crack model for concrete and embedded truss elements adopting Monti-Nuti model for the reinforcement. The aim of this paper is to validate this type of analysis by comparing the obtained results with experimental outcomes of two different RC slender walls, a T-shaped wall and a U-shaped wall, tested under quasi-static bidirectional cyclic load. In particular, the focus is on the comparison between different crack models (Fixed and Rotating crack models) and on the calibration of the Monti-Nuti model parameters for steel. NLFEA is found to acceptably simulate both the in-plane and out-of-plane behaviour observed during the experimental tests. The present work is the starting point for future research in which parametric studies on the influence of reinforcement content and detailing will be performed, assessing their influence on the bidirectional response of RC walls and namely on other less known deformation modes such as out-of-plane instability.

The punching shear resistance formulation provided by Model Code 2010 is calibrated on the basis of experimental tests on isolated slabs supported on columns. According to Level of Approximation approach, several quantities are required for the design punching shear resistance assessment, like the resisting moment and the radius of the line of moment contraflexure. In this paper specific formulations are provided to adjust these quantities in order to take into account for moment redistribution and compressive membrane action effects. The punching shear resistance, mostly investigated for axisymmetric cases, in terms of loading and boundary conditions, will be analysed referring to actual rectangular RC continuous floors with orthogonal reinforcement layouts, largely adopted in practice. The results of nonlinear finite element analyses, carried out using PARC_CL crack model, are post-processed according to the Critical Shear Crack Theory to predict the punching shear strength of the continuous slab.

The use of Natural Fibers (NFs) in Fiber-Reinforced Cementitious Composites (FRCCs) is an innovative technical solution, which has been recently employed also in High-Performance FRCCs. However, NFs are generally characterized by complex microstructure and significant heterogeneity, which influence their interaction with cementitious matrices, whose identification requires further advances in the current state of knowledge. This paper presents the results of pull-out tests carried out on sisal fibers embedded in a cementitious mortar. These results are considered for identifying the bond-slip law that describes the interaction between the sisal fibers and the cementitious matrix. A theoretical model, capable of simulating the various stages of a pull-out test, is employed as part of an inverse identification procedure of the bond-slip law. The accuracy of the resulting simulations demonstrates the soundness of the proposed theoretical model for sisal fibers embedded in a cementitious matrix.

With improved insulation standards over the last 30 years, and with energy efficiency becoming an ever more important design consideration, is necessary to provide a solution to the architectural and engineering problem of creating a thermal break while still providing a structural connection. Thermal bridges occurs when a more conductive (or poorly insulating) material allows an easy pathway for heat flow across a thermal barrier. The most common form is probably within the balcony slab which is usually uninsulated. With an “ad hoc” system is possible to eliminate this kind of problem. Effective thermal insulation using special systems reduces the risk of high levels of condensation, mould formation and the associated damage caused along the ceiling slabs inside of balconies. Thermal outflow and energy loss through the balcony slab is minimized. This paper analyse a specific solution that can guarantee a load capacity connection for balcony slab and at the same time a thermal efficiency. Moreover will be described the design model and the thermal performance analysis in winter and summer situation.

The paper presents a summary of the results of the experimental and analytical research on Improved fastening systems of cladding wall panels of precast buildings in seismic zones, performed within the scope of the European Project Safecladding (EU Programme FP7-SME-2012-2 – Grant Agreement n. 314122), as codified in the pertinent documents issued by the research Consortium in terms of Design Guidelines for practical applications. Further than the investigation on the current fastening systems and the related acceptability analysis for existing structures, the paper deals with the specific design criteria for the isostatic, integrated and dissipative fastening systems that should be the basis for the new precast constructions in seismic zones.

This paper is intended as a practice-oriented contribution about the use of sustainable Fiber-Reinforced Concrete (FRC) in the design of structural members according to the provisions of the current codes and guidelines. More specifically, the work focusses on Hybrid Industrial/Recycled Steel Fiber-Reinforced Concrete (HIRSFRC) realised by combining tailored Industrial Steel Fibers (ISFs) with Recycled Steel Fibers (RSFs), the latter being obtained by recycling waste pneumatic tyres. First, the results of a series of experimental tests, carried out for characterising the behaviour of the aforementioned materials, are summarised. They are specifically considered for evaluating the parameters that are generally considered for describing the post-cracking response of FRC. Then, a parametric analysis on the sectional behaviour of beams made of the aforementioned HIRSFRCs is proposed: this is intended at highlighting the influence of the material behaviour on the ultimate bending moment and curvature of structural members.

In the last years the knowledge of the punching failure in R/C slabs increased thanks to several scientific studies. The progress obtained in this field is considerable, nevertheless achieved results are only taken into consideration by few Codes. The most updated code is the Model Code 2010, which adopted the Critical Shear Crack Theory (CSCT) for the punching shear capacity of R/C slab-column connections. At the same time, the EC2 formulation for punching is under revision, but the new formulation will not be available before three-four years. In this paper, the authors discuss main code provisions (ACI, current EC2, two proposals for revision of EC2, MC 2010, old Italian Recommendations) for punching shear capacity of R/C flat slabs without shear reinforcement. Through a parametric analysis, the authors investigate how each code takes into account the influence of main variables, which come into play in the punching phenomenon, on the evaluation of the punching capacity. Finally, results of each code formulation are compared with different literature experimental data.

Even though different versions of the Friction Pendulum Devices (FPD) can be found on the market and their effectiveness has been extensively proven by means of numerous experimental campaigns carried out worldwide, many aspects concerning their mechanical behaviour still need to be clarified. These aspects concern, among others: (1) the sequence of sliding on the several concave surfaces, (2) the influence of temperature on the frictional properties of the coupling surfaces, (3) the possibility of the stick-slip phenomenon, (4) the possibility of impact-induced failure of some components, (5) the geometric compatibility, and so on. These aspects are less clear the larger the number of concave surfaces of which the device is composed. This paper presents a new way of modelling the mechanical behaviour of the FPDs, by fulfilling: (1) geometric compatibility, (2) kinematical compatibility, (3) dynamical equilibrium, and (4) thermo-mechanical coupling.

Experimental campaigns are a key tool for the evaluation of the behaviour of Masonry Infilled Reinforced Concrete (RC) frames. The case of masonry infills in RC frames is also a regional feature making the homogenous classification for a database a real challenge. This first attempt of a Masonry Infill Database (MID) includes a preliminary selection of experimental tests carried out on models of masonry-infilled RC frames under quasi-static or pseudo-dynamic loading. Each test is characterized in order to include, in a homogenous framework, all the relevant aspects of different experimental campaigns for easy access to the data for future applications. A Damage Classification is introduced, valid for both solid infill panels and for infill with openings. Finally, all monotonic backbones are fitted with a force-displacement piecewise linear approximation for future applications in Performance Based Earthquake Engineering.

Current regulations require surveys on materials in order to identify one or more representative values of the in-situ concrete strength. In this context, the SonReb method is widespread. It correlates the in-situ concrete strength with the ultrasonic pulse velocity and rebound-hammer index. The method improves the reliability of both non-destructive methodologies that are less reliable if considered separately. However, the method neglects the numerical dispersion of the acquired resistances, making uncertain the reliability of every representative value identified. Uncertainty is inherent not only in the variability of the parameters that determine the values, but also in the use of literature formulations calibrated on “recurring concretes”, i.e. concretes characterized by properties evenly variables (age, w/c ratio, …) that don’t allow wider use. In this work, a critical review of the SonReb method is proposed, through a purely statistical approach with the aid of surveys on some school buildings in the province of Foggia built in the 60s and 80s.

New phase change materials (PCMs) are promising fillers for the realization of multifunctional concretes, combining good mechanical properties with enhanced thermal storage capabilities within building envelope. These materials are currently receiving a growing interest in the scientific literature. Encapsulated PCMs result particularly suitable for applications in concrete. This paper presents a research on concretes doped with different contents of PCMs, up to the 5% of the total weight. Physical, mechanical and thermal experimental tests were carried out, in order to investigate the physical properties, the stress-strain behaviour, the ductility, the compressive strength, as well as the thermal conductivity, the diffusivity and the specific heat capacity of the novel concretes. The results of thermal tests demonstrated the effective enhancement of the thermal inertia of the materials, while mechanical tests showed performances compatible with structural applications. Overall, new multifunctional concretes with PCM inclusions appear promising for achieving sustainable and lightweight concrete structures.

External unbonded rebars represents a suitable strengthening technique for the retrofitting of existing Reinforced Concrete (RC) members. Advantages regard the ease of installation, a minimum invasiveness and possibility of future inspections. Structurally, increment of flexural stiffness and bearing capacity and enhancement of shear-flexure behavior can be achieved. The presence of both bonded and unbonded bars introduces a change in the way the shear actions are resisted. Unbonded rebars develop an arch action component, with no bond present and constant force in the rebars, in addition to the beam action component, normally developing in presence of bonded bars. The present paper reports the results of four point loading tests on full-scale beam, with the aim of studying the influence of different bond condition. Moreover, the Double Harping Point technique, using external rebars and vertical deviators, is presented, with attention to the definition of the vertical equivalent stiffness of the deviators.

The balanced lift method is a building bridge method that was developed at the TU Wien. The most common methods to build bridges are the ones using falsework or the cantilever method, but a rather uncommon method, the lowering of arches is seen as the origin of the balanced lift method. The idea was to create a method which would allow a bridge to be built in a very fast manner without the usage of falsework, using prefabricated elements and mounting all parts together in a position – in this case vertically – that would simplify the construction process. In order to reach the final state of the bridge, the vertically assembled parts are rotated into their final horizontal position. This article contains a description of the development of the method, a large scale test will be portrayed and an already designed bridges using the balanced lift method will be shown.

Composition and microstructure of hardened cement paste have important influences on the properties of concrete exposed to high temperatures. An extensive experimental study was carried out to analyse the post-heating characteristics of concretes subjected to temperatures up to 800 °C. Major parameters of our study were the content of supplementary materials (slag, fly ash, trass) of cement (0, 16 or 25 m%) and the value of maximum temperature. Our results indicated that (i) the number and size of surface cracks as well as compressive strength decreased by the increasing content of supplementary materials of cements due to elevated temperature; (ii) the most intensive surface cracking was observed by using Portland cement without addition of supplementary materials. The increasing content of the supplementary material of cement increased the relative post-heating compressive strength. Tendencies of surface cracking and reduction of compressive strength were in agreement, i.e. the more surface cracks, the more strength reduction.

The standard finite elements approach for the dynamics of curved beam is usually based on the same energy functional used for straight beam, in other words an energy form that is essentially derived from de Saint–Venant’s theory. In case of strongly curved elements this approximation yields to not negligible errors, in particular for stress assessments. For this reason, in this work a different formulation, based on the Winkler’s simple kinematic assumptions, is adopted. In this way a non diagonal constitutive matrix is obtained and the computational efficiency of NURBS (Non Uniform Rational B–Splines) shape functions is added to an accurate representation of the constitutive relations. In this paper the natural frequencies and mode shapes of plane curved concrete beams are obtained. Computational cost and results accuracy is assessed with respect to closed form solutions and literature results.

When dealing with large scale seismic vulnerability assessment, usual FEM model based software cannot be a suitable choice to capture the lateral behaviour and seismic capacity of each of the several buildings located in that area. Approximate methods based on the fundamental of structural analysis could be more appropriate. They are practical due to their ease of use and capability to drive to results, even approximated, starting from few input data available. Therefore, they are especially suitable when the full knowledge of structural details cannot be available and the computational effort has to be strongly limited. This study presents the review of some simplified pushover methods available in the literature. Then a combined use of two approximate procedures, each addressed to a different aim, is proposed. These methods have been applied to RC frame structures, to preliminarily compare their effectiveness in simulating the “exact” results would come from a professional FEM structural software.

This work is inspired by the idea of dissipating seismic energy at the base of prefabricated RC columns via semi-active (SA) variable dampers exploiting the base rocking. It was performed a wide numerical campaign to investigate the seismic behavior of a precast RC column with a variable base restraint. The latter is based on the combined use of a hinge, elastic springs, and magnetorheological (MR) dampers remotely controlled according to the instantaneous response of the structural component. The MR devices are driven by a SA control algorithm purposely written to modulate the dissipative capability so as to reduce base bending moment without causing excessive displacement at the top. The proposed strategy results to be really promising, since the base restraint relaxation, that favours the base moment demand reduction, is accompanied by an high enhancement of the dissipated energy due to rocking that can be even able to reduce top displacement in respect to the “fixed base rotation” conditions.

Starting from a novel gradient-based method for the performance-based seismic design (PBSD) of framed RC structures, proposed by one of the authors, some improvements are presented in order to take into account the damage-induced stiffness degradation at larger response values. The method allows for the computation of the values of selected independent design variables (beams and column sections and reinforcement) leading to the attainment or non-exceedance of pre-defined mean annual frequencies for multiple limit states, i.e. incorporating control of the seismic risk during the design phase. The improvement is accomplished by doubling the number of equivalent linear analyses of seismic performance at each point in the design space, implementing an intermediate element-by-element damage assessment after the first analysis. The procedure is exemplified with reference to a 15-storey RC plane frame building.

The non-linear behaviour of concrete structures is the result of a series of phenomena, as material non-linear constitutive law and cracking process. As a consequence, in order to understand the behaviour of reinforced concrete members from elastic field to ultimate condition, is necessary to use instruments able to simulate the material damaging evolution under growing loads. Commercial non-linear finite elements codes are generally able to simulate concrete behaviour with good approximation when a progressive incremental load is applied. However, the same result could not be reached under a cyclic loading. In this work two commercial non-linear finite element codes have been considered in order to assess the skill of these codes to simulate non-linear concrete behaviour under cyclic loading. The results of six laboratory tests on shear walls have been compared with the ones obtained by means of numerical models and some conclusions on the numerical predictions are presented.

Nowadays, short-medium span steel-concrete composite I-girder bridges (SCC) are very popular, owing to their short construction time and reduced costs. Their limited weight makes their use adequate also for seismic areas, even though their seismic behaviour has not been yet adequately investigated. With this aim, within the European project (SEQBRI), the seismic behaviour of new pier-to-deck connections entailing the use of concrete cross-beams (CCB) has been recently studied. This paper shows the results of a comprehensive experimental investigation on this kind of connections conducted with the aim of characterizing the hysteretic behaviour and calibrating a component-based model for seismic analysis. Three different type of connection have been tested: one designed according to the standard DIN-FB104, generally utilized for gravity loads only, and other two, proposed for bridges located in low and medium intensity seismic prone areas. Based on different resistant mechanism, these latter have demonstrated a good behaviour in terms of strength and ductility.

After recent seismic events, the topic of seismic prevention and mitigation in historical centres is become very important, in particular for a seismic prone areas, like Italy, Greece, Portugal, in which a lot of historical towns, for high quantity of old buildings and for their urban structure, suffered a lot of damages. In the past, for this reason, the Authors described and discussed a strategy for seismic prevention and mitigation of historical centres, analyzing them in terms of structural safety. This approach was based on two relevant steps: the first is to study the Urban Risk, the second is to program the Post-Earthquake Activity. The first activity is the analysis of a complex system aiming to individuate the nodal fragility, the second tends to evaluate the buildings safety and the occupancy conditions for these buildings.In this paper a particular aspect of this topic will be discussed, i.e. how different typologies of buildings, that coexist in historical towns, could influence the reconstruction strategy. In fact, when one thinks to an old building isn’t only a masonry historical building, an old building could be a more recent r.c. building designed without any seismic provisions or, as unfortunately usual, realized with poor quality material. Considering that in recent seismic events often this class of buildings caused a lot of damages and deaths, an efficient procedure to approach the impact of r.c. structures on seismic prevention and mitigation in historical centres has to be considered a fundamental goal to reach.

Recently, as a result of seismic events occurrences in Italy, building safety has become a topic of considerable interest. Most of existing reinforced concrete frame buildings designed for vertical loads only and without construction details, which guarantee ductility and dissipative capacity. Then it is necessary to develop a reliable and practical analysis procedure for professional use.This is confirmed by intense research activities to identify the capacity and the safety level of existing structures. Between existing approaches, the Incremental Dynamic Analysis (IDA) is considered to be one of the most accurate methods to estimate the seismic demand and capacity of structures. However the executions of many nonlinear response history analyses (NL_RHA) are required, therefore approaches non-linear static analyses based are studying to aim less onerous methods. The research discussed in this paper deals with the proposal of an efficient Incremental Modal Pushover Analysis (IMPA) to obtain capacity curves by replacing the nonlinear response history analysis of the IDA procedure with Modal Pushover Analysis (MPA). Finally, these approaches were applied to an existing case study that is a concrete framed building of strategic relevance.

This paper investigates local problems involved in the transfer mechanisms of inertia forces acting at the level of the concrete slab of typical steel-concrete composite bridge decks. In detail, the behaviour of the shear connection, usually designed with only reference to non-seismic loads at the ultimate limit state, is studied considering shear forces descending from both horizontal and transverse seismic actions. Some results concerning twin-girder steel-concrete composite bridge decks characterised by different static schemes are presented and the distribution of longitudinal and transverse forces acting on the shear connection is discussed. First results demonstrate the significance of properly considering seismic induced forces in the design of the steel-concrete shear connection and support the need of further investigations.

Incremental dynamic analysis (IDA) is a procedure in which a structure is subjected to a suite of ground motion records, scaled to multiple levels of intensity and leading to corresponding curves of response versus intensity. However, implementation of IDA usually involves a significant computational effort. In this work, a simple and efficient solution for IDA analysis with only few points, based on the structural response to un-scaled records (a.k.a the “cloud”), has been implemented. The transverse frame of a shear-critical seven-storey older RC building in Van Nuys, CA, which is modeled in Opensees with fiber-section considering the flexural-shear-axial interactions and the bar slip, is employed. It is demonstrated that the simplified IDA, obtained based on a significantly lower computational effort with respect to the full IDA, provides reliable results in terms of the statistics of structural response (e.g., mean and mean plus/minus one standard deviation) versus intensity and structural fragility.

Reinforced concrete structures in service may be affected by aging, which may include changes in strength and stiffness assumed in structural design, in particular when the concrete is exposed to an aggressive environment. In this context, this paper provides a computational probabilistic approach to predict the time-evolution of the mechanical and geometrical properties of a statically determinate r.c. structural system (i.e. bridge pier) subjected to corrosion-induced deterioration, due to diffusive attack of chlorides, in order to evaluate its service life. Adopting appropriate degradation models of the material properties, concrete and reinforcing steel, as well as assuming appropriate probability density functions related to mechanical and deterioration parameters, the proposed model is based on Monte Carlo simulations in order to evaluate time variant axial force-bending moment resistance domains, with the aim to estimate the time-variant reliability index. Finally, an application to estimate the expected lifetime of a r.c. bridge pier is described.

Limitation of monetary losses due to earthquakes can improve resilience in developed countries. Computation of losses with the PEER performance-based earthquake engineering framework (Porter 2003) normally entails performing a number of Non-linear Response History analyses as a basis for assessment of expected Engineering Demand Parameters and associated losses, that is an elaborate and time-consuming task. In (ATC 2012) an alternative quicker approach relying on simplified modeling and analysis with SPO2IDA is also envisaged. This paper tests the applicability of simplified method using pushover based analysis and CSM method. In particular, it compares the losses obtained for a non-conforming reinforced concrete moment frame building starting from the classical approach, i.e. based on Non-linear Response History analyses, with the one computed with pushover-based assessment. Moreover, it evaluates the reduction of losses after building retrofit with the pushover-based analysis.

This paper presents the results obtained during an experimental campaign carried out in order to investigate the behaviour of reinforced concrete beams strengthened on shear with composite materials. In order to compare their performance, two different strengthening techniques were used: Fibre Reinforced polymers (FRP) and Fibre Reinforced Cementitious Matrix (FRCM) composites. The beams were simple supported and a traditional four point bending scheme was used to execute the tests. Midspan displacements were measured using linear variable transducers (LVDTS) while strain gauges were placed on the stirrups to measure strains.

This paper outlines a rational strategy for retrofitting Reinforced Concrete (RC), which is based on combing member- and structure-level techniques in order to achieve optimal design objectives in a Performance-Based approach. Member-level techniques (such as confinement with composite materials, steel or concrete jacketing) are supposed to enhance capacity of single members, whereas structure-level techniques (generally based on introducing steel bracings systems or shear walls) aim to reduce the seismic demand on the existing frame as a whole. A novel procedure, based on a “dedicated” genetic algorithms, is developed by the authors for selecting “optimal” retrofitting solutions, among the technically feasible ones, obtained by combining alternative configurations of steel bracing systems and FRP-confinement of critical members. The main assumptions about the representations of “individuals” and the main information about the genetic operations (i.e. selection, crossover and mutation) are summarised in the paper. Finally, a sample application of the procedure is proposed with the aim to demonstrate its potential in selecting rational retrofitting solutions.

An analytical model in a closed form able to reproduce the monotonic flexural response of external R.C. beam-column joints with smooth rebars is presented. The column is subjected to a constant vertical load and the beam to a monotonically increasing lateral force applied at the tip. The model is based on the flexural behavior of the beam and the column determined adopting a concentrated plasticity hinge model including slippage of the main bars of the beam. A simplified bilinear moment-axial force domain is assumed to derive the ultimate moment associated with the design axial force. For the joint a simple continuum model is adopted to predict shear strength and panel distortion. Experimental data given in the literature are utilized to validate the model. Finally, the proposed model can be considered a useful instrument for preliminary static verification of existing external R.C. beam-column joints with smooth rebars.

In the present paper, a simplified model to determine the moment-axial force domain of the cross-section of reinforced concrete columns subjected to corrosion process is presented. The model considers members with square and rectangular cross-sections and it accounts for cover spalling, buckling of longitudinal reinforcing bars, loss of bond of bar in tension, reduction of confinement pressures (due to the reduction of the area of stirrups and cracking of concrete induced by rust formation). The analytical expressions for prediction of the area reduction of steel, bond strength and critical load of longitudinal bars utilized were verified against experimental data available literature.

Existing RC buildings of the Mediterranean area commonly show high variability in the material mechanical properties because of the construction age and manufacturing processes. Such a variability has been confirmed by number of in-situ tests performed during the reconstruction process in the aftermath of L’Aquila 2009 earthquake. In this context, destructive and non-destructive characterization tests are useful supporting tools to estimate the actual concrete mechanical properties and to improve the accuracy of the seismic capacity assessment. The paper reports of a wide material characterization program consisting of destructive and non-destructive tests carried out on a building severely damaged by the L’Aquila 2009 earthquake. Due to poor concrete mechanical properties and seismic structural weaknesses, the building was demolished. Portions of the structural systems have been extracted before the building demolition, subjected to material characterization tests and then tested in laboratory. The comparison between the two sets of material characterization test programs and the correlation with the experimental performances of an RC column tested under compressive axial load is presented herein.

This paper reports the design and the realization of the energetic renovation of a residential building owned by ALER and located in Cinisello Balsamo (MI), by mean of the installation on the existing facades of an innovative insulating prefabricated sandwich panel, for a total of about 520 m2 covered. The energetic renovation process has been organized in the following steps:survey campaign of the existing building’s envelope by means of laser scanning technologies and thermographic survey for the identification of non-homogeneous parts of the building structure, to support the technological design as well as the installation of the prefabricated panels;use of Building Information Modeling (BIM) aimed at supporting the design of both the prefabricated panels and the anchoring systems, towards the automation in the installation of the elements as well as the energy performance evaluation over time;architectural and executive design of the energetic renovation and manufacturing of 186 insulating prefabricated panels, for a total of 28 different typologies, having different sizes, colors and finishing (with and without specific textures);panels’ installation to the existing building facades by means of steel profiles and realization of the finishing works.Before and after the installation of the prefabricated insulating panels, a dedicated monitoring campaign was performed for the evaluation of the thermal performance of the building, whose main results are also provided in this paper. This energetic renovation project has been performed in the framework of the European research project EASEE (“Envelope Approach to improve Sustainability and Energy efficiency in Existing buildings”), funded by the European Union under the 7th Framework Programme for Research and Development. This project, along its four years of duration, was aimed at developing innovative solutions for the energy upgrading of multi-storey residential buildings built before 1975, in a historical period in which the focus on energy efficiency was not so pressing, thus being highly energy-consuming buildings.

The durability of concrete can be reduced by several chemical phenomena, among them the alkali-silica reaction (ASR) plays a fundamental role. Such reaction can have a severe impact on structure safety and functioning. This work deals with the evaluation of the effects of ASR in existing concrete dams. To this purpose, a phenomenological two-phase isotropic damage model, describing the degradation of concrete, is presented and used to simulate the behaviour of concrete dams affected by ASR. This model takes into account the simultaneous influence of both humidity and temperature through two uncoupled diffusion analyses: the heat diffusion analysis and the moisture diffusion analysis. The role of the temperature and humidity fields variations on the development of the deleterious reactions is discussed in the case of an arch dam. The numerical analyses, performed with the proposed thermo-hydro-damage model, allowed to predict the structural behaviour both in terms of reaction extent and increase of crest displacements.

This paper deals with the rehabilitation and maintenance of the Lago Colombo Dam, owned by Enel S.p.A. since 1962. Comprehensive studies of the dam condition and behaviour pointed out the necessity of important rehabilitation works, to improve the safety conditions and to ensure the efficiency of the dam. Its original gravity behaviour was restored and the arch effect was reduced. The final solution consisted in the crack grouting with special self-compacting mineral mortar and in the carrying out of two new vertical structural joints, by means of slot cutting (2 cm wide) with diamond wire. Others additional improvement works were also carried out. The works started in 2010 and were successfully completed in 2011; in summer 2012 and 2013, the reservoir was re-impounded and the dam behaviour monitored after the rehabilitation. The dam monitoring of the last years has confirmed the change of dam behaviour as required in the rehabilitation project.

Concrete sensitivity to spalling in fire is still a critical issue, as no reliable predictive model is currently available. Hence, so far, experimental testing is the most effective means of investigation. This is the reason why an experimental setup has been designed (and discussed in the RILEM TC 256 SPF) by the authors, based on 800 × 800 mm concrete slabs installed in a steel frame, aimed at applying a biaxial membrane compression. Load and slab thickness can be adjusted in order to simulate the actual service conditions of concrete elements such as tunnel lining segments. The loading system is placed on a horizontal furnace powered by a propane burner fitted with an automatic control system, allowing to follow the prescribed heating curve. This setup allows comparing different concrete mixes as regards their sensitivity to spalling in realistic service conditions and can be of considerable help in initial material testing for strategic infrastructures such as tunnels.

Mean annual financial losses due to seismic events in Italy are about 2–3 billion euro. For this reason, in recent years increasing attention has been placed on strategies to reduce the seismic risk of the national building stock. In this work, a comparative seismic loss analysis of an infilled R/C building is performed using the FEMA P-58 probabilistic framework and the tool PACT. The objective is to evaluate how the structural modeling and the characterization of structural and nonstructural elements fragility can affect the loss estimation. Fragility and consequence functions for discrete damage states are assumed for structural and non-structural components. A case study prototype typical of Italian pre-1970 R/C infilled buildings is chosen. Nonlinear Incremental Dynamic Analyses (IDA) are performed for three 2D modeling configurations. Financial losses are expressed as median values of repair costs at different hazard levels or in terms of Expected Annual Loss (EAL).

This study deals with the assessment of the shear strength characteristic value (V _rck ) limited by the concrete strut crushing for existing reinforced concrete (RC) beams on the base of the available material data. A procedure to determine V _rck is presented and applied to two existing RC beams extracted from an old structure built in the early 1900s. This procedure requires: (i) an analytical or numerical model for the beam shear strength, (ii) mean and standard deviation values for each uncertain basic variable and (iii) a proper formulation for the tolerance factor depending on amount of data, assumed fractile and given confidence level. The shear strength model adopted in this study is the one proposed by the Italian Code NTC 2008 for beams with transversal steel reinforcement. Several non-destructive tests (namely, rebound and sonic tests) and destructive tests on concrete were performed, and the experimental outcomes showed a great variability of the compressive strength along the same beam, as usual for many old concretes. For that reason, V _rck values for each beam were calculated assuming different knowledge levels about the concrete compressive strength. Each level of knowledge is defined taking into account a different combination of available data about the compressive strength carried out from destructive tests. A comparison among the V _rck values obtained for each knowledge level is shown to draw useful considerations about the beam shear strength assessment based on materials test data.