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PERPETUATE guidelines for seismic performance-based assessment of cultural heritage masonry structures
Bulletin of Earthquake Engineering
Abstract
Ancient monumental masonry buildings are complex structures that were not based on an engineered design, underwent many transformations during their life and often present lack of connections among the structural elements. Earthquakes are the main cause of damage for ancient masonry structures and, in order to reduce their vulnerability with compatible and light interventions, it is necessary to have accurate models for the seismic analysis, able to simulate the nonlinear behavior of masonry, and a well defined performance-based assessment procedure, aimed to guarantee the acceptable level of risk for the occupants and for the conservation of the monument itself. The paper outlines the guidelines that were developed within the PERPETUATE European research project. The wide variety of architectural assets is classified and the related proper modeling strategies are identified; moreover, immovable artistic assets are considered in the assessment. A displacement-based approach is adopted, because these structures crack even for low intensity earthquakes and can survive severe ones only if they have a sufficient displacement capacity. Safety and conservation requirements are proposed by considering distinct sets of performance levels, related to use and safety of people, conservation of the building and of the artistic assets that might be present. Some indications on the seismic hazard assessment are provided, considering the distinctive features of some types of ancient structures. Within the fundamental knowledge phase, sensitivity analysis is proposed in order to address and optimize the in-situ investigation and to define proper confidence factors, aimed to consider epistemic and statistical uncertainties. Different modeling approaches and methods of analysis are considered, depending on the characteristics of the structure; both static pushover and incremental dynamic nonlinear analyses are considered. Related verification procedures are defined to evaluate the seismic intensity measure, and the corresponding return period, which is compatible with each performance level that must be fulfilled.
... This issue was addressed by some research projects, e.g. [15], in compatibility with building codes, see [4], [5], [6], [16], [17], aimed at providing guidelines for the application of modeling approaches and analysis methods, and for safety assessment criteria at global and local levels. ...
... The modeling approaches can vary in describing the mechanical behavior of masonry, i.e., from materialscale to macro element-scale models, as well as in terms of discretization of elements and representation of damage, see [15], [20], [21]. The classification proposed by D'Altri et al. [21] is illustrated in Figure 2.6. ...
... In EF-based approaches, the building behavior is modeled by simulating the lateral IP response of each structural macro element according to equivalent material properties. For this reason, the computational effort is drastically reduced [15]. Note that only beam-based EF models according to the classification by D'Altri et al. [21] are considered in the following description. ...
The research work aims to define harmonized criteria for code-based seismic assessment of URM structures with box-like behavior when using different modeling approaches based on Finite Element (FE) and Equivalent Frame (EF) methods (implemented in DIANA and 3Muri software packages, respectively), and pushover analysis. To this aim, different benchmark structures at the pier and wall scales were selected. Given that part of the work was developed within the scope of Subtask 10.3 of the 2022-2024 DPC-ReLUIS Project, additional FE and EF-based software packages were considered whose cross-comparison allowed the proposal of general procedures for controlling results.
... Concerning the macroelement criterion, the goal is to monitor the possible concentration of damage in specific portions of the URM building that could be incompatible with the safety requirements (e.g., to identify the activation of a soft story mechanism in local portions); this is particularly relevant in the case of structures with irregular configurations or in the presence of flexible diaphragms. The first proposal to detect such conditions was introduced in [31], using the inter-story drift (θ w,l ) within a particular story or level (l) of a wall (w) as an engineer demand parameter to be checked against the exceedance of the predetermined threshold. In [31], the computation of the inter-story drift is performed according to Equation (1): ...
... The first proposal to detect such conditions was introduced in [31], using the inter-story drift (θ w,l ) within a particular story or level (l) of a wall (w) as an engineer demand parameter to be checked against the exceedance of the predetermined threshold. In [31], the computation of the inter-story drift is performed according to Equation (1): ...
... The CSM, initially formulated and pioneered by Freeman [34] and integrated into Standards such as [10], is employed in the analysis of the case study, using the methodology illustrated in [31]. The CSM obviates the strict requirement of converting the capacity curve into an equivalent bilinear, and it makes use of reduced spectra (see Equations (10) and (11)) based on the concept of equivalent damping ξ (Equation (8)). ...
This paper presents, firstly, an overview of the nonlinear static procedures (NSPs) given in different codes and research studies available in the literature, followed by the results achieved by the authors to evaluate the reliability of the safety level that they guarantee. The latter is estimated by adopting the fragility curve concept. In particular, 125 models of a masonry building case study are generated through a Monte Carlo process to obtain numerical fragility curves by applying various NSPs. More specifically, among the NSPs, the N2 method (based on the use of inelastic response spectra) with different alternatives and the capacity spectrum method (CSM)-based on the use of overdamped response spectra-are investigated. As a reference solution to estimate the reliability of the nonlinear static approach, nonlinear dynamic analyses (NLDAs) are carried out using the cloud method and a set of 125 accelerograms; the results are post-processed to derive fragility curves under the assumption of a lognormal distribution. The focus of this investigation is to quantify the influence that the NSP method's choices imply, such as the criteria adopted to calculate the displacement demand of a structure or those for the bilinearization of the pushover curve. The results show that the N2 methods are all non-conservative. The only method that provides a good approximation of the capacity of the analyzed URM structures as derived from NLDAs is the CSM. In particular, bilinearization is proven to have a relevant impact on the results when using the N2 method to calculate displacement capacities, whereas the CSM method is not affected at all by such an assumption. The results obtained may have a significant impact on engineering practice and in outlining future directions regarding the methods to be recommended in codes.
... However, the structural assessment and the vulnerability analysis of historical buildings are complicated tasks. This is mainly due to the transformations that the buildings have undergone over the years and the difficulty in obtaining the as built information [8]. Furthermore, this type of analysis requires a complex study and specialised technical skills. ...
... For the seismic assessment of historical buildings, nonlinear static analysis (NLSA) is usually carried out [12]. Despite its simplifications, it has been proved to be a suitable approach for a preliminary assessment of historical buildings, as suggested in [8,13]. ...
... Owing to the impossibility of performing destructive campaigns, non-destructive tests (NDT) are usually carried out for the structural analysis of URM heritage buildings. Operational modal analysis (OMA) is one of the most used NDT to calibrate numerical models, as suggested in [8]. This enables obtaining the dynamic properties of the buildings. ...
... Former investigations have addressed the fragility assessment of unreinforced masonry buildings by measuring structural damage in terms of drift ratio [37,38,62,63]. The values of drift limits reported in these investigations will serve as a reference to establish the asymptotic values of EDPs for deriving analytical fragility functions at collapse DS. ...
... Finally, the GC is revealed by the appearance of the flatline at max(Δ r ) = 40 mm, or global drift ratios approaching 0.45 %. It should be noted that these observations are coherent with the findings of previous investigations on the global drift ratio limits of unreinforced masonry buildings [37,38,62,63] for the derivation of fragility functions at different levels of DS, as stated in Section 2.1. Furthermore, recent investigations [88][89][90] identified, numerically and experimentally, drift-based DSs for historical masonry structures, showing consistency with the numerical results attained herein. ...
... A direct relation is defined between the peak ground acceleration (PGA) associated with a scaled spectral shape and the displacement demand for the rocking mechanism of each façade wall. This relation is developed through the construction of incremental static analysis (ISA) curves, obtained according to the procedure suggested by PERPETUATE Guidelines (Lagomarsino and Cattari 2015), and multiple stripe analysis (MSA) for discrete ranges of PGA (Nale et al. 2021, Baker 2013. The obtained discrete points are fitted via the maximum likelihood estimation method and by adopting a lognormal cumulative function, as widely adopted in the literature (Baker 2015), with reference to different limit states, such as activation of the mechanism, moderate and severe rocking (LS0, LS1 and LS2, respectively). ...
... As regards the relation between the peak ground acceleration associated with a scaled spectral shape and the displacement demand, ISA curves are developed according to the procedure suggested by (Lagomarsino and Cattari 2015). For this purpose, ADRS are normalized with respect to their PGA and the following expression is adopted to define the scale factor IM, representing the value of PGA/g that provides a displacement demand d* equal to the capacity d: ...
The paper is devoted to the large-scale assessment of the vulnerability of masonry church façades to out-of-plane mechanisms and of the positive effect provided by anchoring devices. In particular, attention is focused on the simple rocking of the main façade of masonry churches that is analysed by means of a displacement-based approach aimed to carry out pushover analysis. Non-linear static analyses, taking into account both geometric non-linearities and frictional resistances provided by the church sidewalls, are firstly performed on a reduced sample (14 façades) of churches located in the Ischia Island (Italy) and, then on an extended sample of 400 façades generated through the Monte Carlo simulation starting from the main geometric parameters of the 14 façades. The contribution of strengthening systems made of steel tie-rods to mitigate the simple rocking is analysed for both samples and their effect in terms of vulnerability reduction, as some design parameters of the tie-rod change, is highlighted by developing the fragility curves for both anchored and non-anchored façades. Fragility curves are, indeed, derived for the 14 and 400 façades using incremental static analysis (ISA) and multiple stripe analysis (MSA). Acceleration-displacement response spectra (ADRS) are considered for the three limit states corresponding to the onset of rocking, LS0, and to moderate and severe motions, i.e. LS1 and LS2, respectively. Finally, the influence of the seismic input variation is examined on both anchored and non-anchored façades and with reference only to the extended sample of 400 façades for LS1 and LS2.
... In this framework, numerous research projects aimed at developing and improving seismic assessment and at retrofitting procedures for historical and cultural heritage, including fortification walls, have been developed in recent years, both at European and national levels. Among these, the PERPETUATE European research project (Lagomarsino and Cattari 2015), contains specific guidelines for the seismic risk assessment of cultural heritage assets and the design of interventions, carried out in compliance with the Performance-Based Approach (Priestley 2000;Cattari and Lagomarsino 2014). To this end, the architectural assets is divided into six classes identified on the basis of the predominant collapse mode (Fig. 4). ...
... Nonlinear kinematic analysis is the most suggested approach for the seismic assessment of masonry structures toward out-of-plane mechanisms (Degli Abbati et al. 2014;Simões et al. 2014;Cattari et al. 2015;Casapulla et al. 2021;Cima et al. 2022Cima et al. , 2023. The application of this approach requires particular attention to the definition of the performance levels which are strictly related to the level of expected damage (Lagomarsino and Cattari 2015). ...
Medieval defensive walls are a distinctive feature of Italian cultural heritage. These structures testify the origins of historical centres and, in some cases, the consequences of the events occurred over time. The typical configuration of medieval defensive walls, generally characterized by high slenderness ratios, out-of-plumb, the absence of deep and adequate foundations, made these elements particularly vulnerable toward seismic actions. This study focused on the assessment of the seismic safety of Italian medieval defensive walls toward out-of-plane failure mechanisms induced by seismic actions. To this end, a simple approach based on the use of generalized dimensionless capacity curves is presented. These curves, derived by the Authors from a calibration process involving a set of selected real cases, allows for a rapid preliminary seismic assessment of masonry walls particularly useful for getting an initial idea of the condition of the walls with respect to seismic actions also considering the presence of pre-existing out-of-plumb configurations. The proposed approach has been applied in the paper to the real case study of medieval walls of Cittadella, a town in northern Italy, considering the pre-existing out-of-plumb configuration. The obtained results have shown the vulnerability of these walls in case of occurrence of masonry disaggregation and, consequently, the importance of performing specific surveys finalized to investigate this phenomenon. The application of the proposed approach has clearly shown its feasibility and usefulness for the seismic evaluation. Moreover, the comparison with the corresponding results obtained by using the actual capacity curves, rather than the generalized ones, has underlined its good level of reliability.
... The capacity in terms of the damage threshold, d DSi , on the other hand, is derived from the capacity curves derived in Step 3. The damage threshold corresponding to DS1 is identified by the spectral displacement (d y ) at the intersection between the capacity curve and a linear branch representing the elastic behavior of the façade wall before the activation of the mechanism. Conversely, the damage threshold of DS2 corresponds to the collapse defined by a damage threshold of 0.40 d 0 , where d 0 is the spectral displacement corresponding to the point where the spectral acceleration (a) is zero [50,65,66] (see Figure 9). spectral displacement corresponding to the point where the spectral acceleration (a) is zero [50,65,66] (see Figure 9). ...
... Conversely, the damage threshold of DS2 corresponds to the collapse defined by a damage threshold of 0.40 d 0 , where d 0 is the spectral displacement corresponding to the point where the spectral acceleration (a) is zero [50,65,66] (see Figure 9). spectral displacement corresponding to the point where the spectral acceleration (a) is zero [50,65,66] (see Figure 9). The derived total dispersion incorporating both the model variability [69] and the record-to-record variability. ...
Unreinforced masonry (URM) buildings in historic urban areas of European countries are generally clustered in an aggregate configuration and are often characterized by façade walls mutually interconnected with adjacent ones. As a result, the seismic performance of buildings in an aggregate configuration can be affected by the mutual interaction between the adjacent units. This interaction, often called the aggregate effect, could significantly influence the level of the seismic vulnerability of URM buildings in aggregate configuration toward in-plane and out-of-plane mechanisms, the latter being the object of the present paper. Traditional methods for assessing the seismic vulnerability of URM buildings neglect the interactions between adjacent buildings, potentially underestimating the actual vulnerability. This study aims to derive fragility curves specific for UMR buildings in aggregate configuration and proposes an innovative methodology that introduces the aggregate effect into an analytical approach, previously developed by the authors for isolated URM buildings. The aggregate effect is modeled by accounting for the friction forces arising among adjacent facades during the development of out-of-plane overturning mechanisms by considering different scenarios, based on how façade walls interact with neighboring structures (e.g., whether they are connected to transverse and/or lateral coplanar ones). The proposed approach is applied to a real case study of an Italian historical center. The obtained results demonstrate that the aggregate effect significantly influences the fragility curves of URM buildings arranged in aggregate configurations. This highlights the importance of considering this effect and the usefulness of the proposed approach for large-scale assessments of seismic vulnerability in historic urban areas, contributing to sustainable disaster risk prevention.
... In this framework, numerous research projects aimed at developing and improving seismic assessment and at retrofitting procedures for historical and cultural heritage, including fortification walls, have been developed in recent years, both at European and national levels. Among these, PERPETUATE European research project (Lagomarsino & Cattari, 2015), contains specific guidelines for the seismic risk assessment of cultural heritage assets and the design of interventions, carried out in compliance with the Performance-Based Approach (Priestley, 2000;. To this end, the architectural assets is divided into six classes identified on the basis of the predominant collapse mode (Fig. 4). ...
... Nonlinear kinematic analysis is the most suggested approach for the seismic assessment of masonry structures toward out-of-plane mechanisms (Degli Abbati et al., 2014;Simões et al., 2014;Cattari et al., 2015;Casapulla et al., 2021;Cima et al., 2022Cima et al., , 2023. The application of this approach requires particular attention to the definition of the performance levels which are strictly related to the level of expected damage (Lagomarsino & Cattari, 2015). More specifically, for heritage assets susceptible to out-of-plane overturning mechanism, in (Lagomarsino, 2015) four DL thresholds were identified on the basis of heuristic criteria (see Fig. 6): ...
Medieval defensive walls are a distinctive feature of Italian cultural heritage. These structures testify the origins of historical centres and, in some cases, the consequences of the events occurred over time. The typical configuration of medieval defensive walls, generally characterized by high slenderness ratios, out-of-plumb, the absence od deep and adequate foundations, made these elements particularly vulnerable toward seismic actions. This study focused on the assessment of the seismic safety of Italian medieval defensive walls toward out-of-plane failure mechanisms induced by seismic actions. To this end, a simple approach based on the use of generalized dimensionless capacity curves is presented. These curves, derived by the Authors from a calibration process involving a set of selected real cases, allows for a rapid preliminary seismic assessment of masonry walls particularly useful for getting an initial idea of the condition of the walls with respect to seismic actions also considering the presence of pre-existing out-of-plumb configurations. The proposed approach has been applied in the paper to the real case study of medieval walls of Cittadella, a town in northern Italy, considering the pre-existing out-of-plumb configuration. The obtained results have shown the vulnerability of these walls in case of occurrence of masonry disaggregation and, consequently, the importance of performing specific surveys finalized to investigate this phenomenon. The application of the proposed approach has clearly shown its feasibility and usefulness for the seismic evaluation. Moreover, the comparison with the corresponding results obtained by using the actual capacity curves, rather than the generalized ones, has underlined its good level of reliability.
... One of the main challenges is the choice of the modeling strategy. Among the possibilities, deeply reviewed in [18,19] and discussed from a seismic engineering viewpoint in [20,21], finite element (FE) models constitute the most common choice for monumental assets. According to the classification proposed in [20], which refers to the modeling and discretization scales, these models may be classified as CCLM (continuous constitutive law models) in which the behavior of the masonry material is described by homogenized constitutive laws of phenomenological or micromechanical derivation. ...
... Among the possibilities, deeply reviewed in [18,19] and discussed from a seismic engineering viewpoint in [20,21], finite element (FE) models constitute the most common choice for monumental assets. According to the classification proposed in [20], which refers to the modeling and discretization scales, these models may be classified as CCLM (continuous constitutive law models) in which the behavior of the masonry material is described by homogenized constitutive laws of phenomenological or micromechanical derivation. The literature is rich in examples of FE models built and employed to analyze the structural behavior of historical masonry structures, such as towers [22], churches and monasteries [23][24][25], fortresses and castles [26,27], and, not least, palaces [28][29][30]. ...
Recent advances in computing performance and simulation tools allow today the development of high-fidelity computational models which accurately reproduce the structural behavor of existing structures. At the same time, advancements in sensing technology and data management enable engineers to remotely observe monitored structures in a continuous and comprehensive way. Merging the two approaches is a challenge recently addressed by the engineering research community, which led to the concept of digital twin (DT)-a simulation model continuously fed by sensor data which, throughout the whole lifespan of the structure, stands as its digital proxy. In the seismic field achieving such a task is still problematic, in particular for large and complex structures such as historical masonry palaces. To this aim, the paper proposes the integrated use of DTs and vibration data to support the seismic structural health monitoring of monumental palaces, discussing a practical application to the historical Consoli Palace in Gubbio, Italy. To overcome the computational limitations of classical approaches, an efficient equivalent frame (EF) model of the palace is built and continuously updated in quasi real-time based on modal information identified from vibration data. The performance and accuracy of the Equivalent Frame model are compared with those of a high-fidelity Finite Element representation, highlighting both their feasibility and limitations. Employing modal data recorded across the 15 May 2021 earthquake, the EF model demonstrates the ability to quickly assess the structural integrity of the palace in the post-earthquake scenario, as well as to forecast the residual capacity with respect to future seismic events.
... In fact, the rocking of façades is the most recurring mechanism in terms of percentage concerning the possible and activated mechanisms, as observed in recent earthquakes [1,5]. Recently, different analytical and numerical approaches were developed to analyze the seismic response of rocking façades [6][7][8][9], also restrained by dissipative devices [10,11] or by optimal economic and environmental retrofitting solutions [12]. ...
... A direct relation is defined between the peak ground acceleration (PGA) associated with a scaled spectral shape and the displacement demand for the rocking mechanism of each façade wall. This relation is developed through the construction of incremental static analysis (ISA) curves, obtained according to the procedure suggested by PERPETUATE Guidelines [7]. ...
Out-of-plane failure of façades is one of the most distinctive local mechanisms in masonry churches recognizable in the aftermath of a seismic event. The purpose of this paper is to derive large-scale fragility curves for masonry church façades using incremental static analysis, and to assess the influence of some parameters on their vulnerability. According to the displacement based approach, pushover analysis is carried out considering both the geometric nonlinearities and the stabilizing contribution of frictional resistances exerted by the church sidewalls. The seismic demand is derived using acceleration-displacement response spectra (ADRS) for different limit states, obtained according to the Italian seismic code. The analyses are addressed with reference to a large sample of masonry churches generated starting from the geometric parameters of a reduced sample of churches hit by the seismic event of 21 st August 2017 in the Ischia Island (Italy). Several geometric aleatory variables, i.e. the length, the height and the thickness of the façade, are treated by means of the Monte Carlo simulation (MCS) to generate a numerical sample of 400 facades. Considering two limit states for rocking (moderate and severe motion), fragility curves are derived for these facades subjected to the same single ground motion scaled at different values of PGA, using incremental static analysis (ISA) and multiple stripe analysis (MSA). Finally, on the same sample of 400 facades , the sensitivity of the fragility curves to the friction coefficient, the length of masonry units and the position of the façade mass center is investigated.
... In fact, during the last decades, several approaches have been proposed based on the use of laser scanners [5][6][7], Unmanned Aerial Vehicles [8,9], and terrestrial photogrammetry [10,11], with which it is possible to determine all the intrinsic irregularities characterising the structural elements geometry of historic buildings. Moreover, most of these buildings are in seismic-prone zones and are constructed with ancient unreinforced masonry (URM) using various construction techniques [12][13][14]. In particular, religious architecture, such as cathedrals, monasteries, and churches, represents a significant portion of heritage buildings, which are characterised by a high level of seismic vulnerability. ...
The evaluation of the structural behaviour of iconic historic buildings represents one of the most current structural engineering research topics. However, despite the various research works carried out during recent decades, several issues still remain open. One of the most important aspects is related to the correct reconstruction of the complex geometries that characterise this type of construction and that influence structural behaviour, especially in the presence of the horizontal loads caused by seismic action. For these reasons, different techniques have been proposed based on the use of laser scanners, Unmanned Aerial Vehicles (UAVs), and terrestrial photogrammetry. At the same time, several analysis methods have been developed that include the use of linear and non-linear approaches. In this present paper, the seismic performance of the Santa Maria Novella basilica and Santa Maria di Collemaggio basilica (before the partial collapse due to the 2009 L’Aquila earthquake) were investigated in detail by means of several numerical analyses. In particular, a series of non-linear time history analyses (NTHAs) were carried out, as reported in the Italian Building Code. To represent the non-linear behaviour of the main structural elements, smeared cracking (CSC) constitutive law was adopted. The geometry of the structures was reconstructed from a complete laser scanner survey of the churches, in order to consider all the intrinsic irregularities that characterise the heritage buildings. Finally, a comparison between the structural behaviour of the two case studies was carried out, highlighting the differences and similar aspects, focusing on possible collapse mechanisms and the identification of the most critical structural elements represented, in both cases analysed, by the main pillars of the transept.
... These buildings often contain significant cultural heritage assets, such as immovable artistic assets, that require conservation and protection. This research was published in Bulletin of Earthquake Engineering, Volume 13, January 2015 [17]. ...
... Considering the relation between the PGA = (ag•S) associated with a scaled spectral shape and the displacement demand, incremental static analysis (ISA) curves are developed according to the procedure suggested by Lagomarsino and Cattari (2015), based on the use of the capacity spectrum method (Freeman 1988). These curves, derived from scaled code spectra, specifically over-damped elastic accelerationdisplacement response spectra (ADRS), represent the relation between the displacement demand and the intensity measure (IM) by changing the secant periods. ...
The out-of-plane failure of façade walls is one of the most typical local mechanisms in masonry churches recognizable in the aftermath of a seismic event. The purpose of this paper is to assess the influence of some geometrical parameters of the façade on its vulnerability to simple rocking and, therefore, to define reliable criteria for identifying homogeneous vulnerability classes. By adopting the displacement-based approach, pushover analyses are carried out considering the stabilizing contributions of the frictional resistances exerted by the sidewalls. The analyses are addressed with reference to a sample of 14 existing masonry churches hit by the seismic event of 21 st August 2017 in the Ischia Island (Italy). Fragility curves for moderate (LS1) and severe (LS2) motions are derived for these façades under 15 ground motions with their site effects (including the occurred seismic input in Ischia) scaled at different values of the peak ground acceleration (PGA), using incremental static analysis (ISA), multiple stripe analysis (MSA) and acceleration-displacement response spectra (ADRS). For the onset of rocking (LS0), depending only on the PGA, fragility curves are developed with reference to the variability of the geometrical parameters of the facades both for the sample of the 14 churches of Ischia and for an extended one (400 façades) generated by means of a Monte Carlo simulation (MCS). Two conditions are considered for the examined façades: a 'free rocking' condition and a 'restraint' condition related to the interlocking with the sidewalls. All the obtained fragility curves are critically discussed in order to identify 'a posteriori' homogeneous classes of seismic vulnerability for masonry church façades for each limit state.
... Among the various methods and modelling approaches that can be adopted for the structural analysis of masonry structures (for a review see D' Altri et al. 2020;Lagomarsino and Cattari 2015;Roca et al. 2010), finite element (FE) methods based on macro-modelling, usually referred to as FE macro-models, and equivalent frame (EF) methods have found the widest application for evaluating the global seismic response of historic masonry buildings. ...
Equivalent frame (EF) methods are increasingly used to evaluate the global seismic response of historic masonry buildings. However, applying these methods to arched structures is challenging due to the lack of a standard EF strategy for masonry arches. This paper proposes a novel EF modelling solution for masonry arches in historic buildings subject to seismic actions. The proposed strategy, which consists in modelling arches as inclined hinged beams, is presented through the application to a case study, the Giuseppe Verdi Politeama Theatre in Carrara, Italy. Nonlinear static analyses were first performed on a finite element (FE) macro-model of a representative arch-pillar system found in the building. The numerical results in terms of damage mechanisms and capacity curves allowed the development of an EF modelling strategy for masonry arches. This strategy was then applied to a three-dimensional EF model of the Politeama Theatre to evaluate its global seismic response through nonlinear static analyses. The results demonstrated the effectiveness of the proposed strategy in accurately simulating the contribution of the arches in resisting horizontal actions.
... In the last decades, several seismic risk studies have been carried out at various scales, driven by a growing public awareness of the importance of safeguarding human life and architectural heritage: at a global scale, it highlighted the research developed by the Global Earthquake Model Foundation (GEM) (Crowley et al. 2013;Silva et al. 2018). In Europe, the research project RISK-UE (Mouroux and Le Brun 2006), LESSLOSS (Flesch 2007), PERPETUATE (Lagomarsino and Cattari 2015) and ESRM20 (Crowley et al. 2021). Other studies can be found in the literature providing tools for seismic risk analysis (e.g. ...
... In this framework, besides the in-plane failure, the most recurrent failure mechanisms surveyed in seismic scenarios involve the out-of-plane behaviour of masonry walls and parts of walls, occurring when these are badly connected to the rest of the building (lack of box-type behaviour) or for local structural/geometrical weaknesses. Frequently, these mechanisms have a relevant impact on the seismic safety of masonry buildings since they may lead to a progressive failure of the whole structure, as confirmed by experimental evidence and several studies on the out-of-plane response of masonry structures (Ferreira et al. 2015, Lagomarsino and Cattari 2015, Sorrentino et al. 2017, Solarino et al. 2019, Giresini 2022). ...
Out-of-plane failure mechanisms of walls are among the most serious life-safety hazard for existing masonry buildings undergoing seismic actions. Limit analysis-based approaches are commonly used to evaluate their seismic assessment, since requiring simplified assumptions for the structural model. However, the use of models not involving the effective interlocking between walls often yields too conservative results in seismic assessment, which may not be realistic and lead to expensive repairs. Seismic codes, such as the Commentary to the Italian technical standard issued in 2019, do highlight the importance of such modelling aspects, though limited only to the simple rocking failure, but structural analysis software have not yet incorporated them properly. In this paper, an advanced macro-block model accounting for frictional resistances, very competitive for high computational efficiency, is adopted to calculate the activation load multipliers for rocking-sliding compound mechanisms and the related crack patterns in masonry buildings, as well as to evaluate the influence of the interlocking effects on the actual performance of masonry walls. The solutions adopted for the implementation of this advanced model in the 3Muri Project software are then presented and discussed with reference to the application of the proposed force-based approach to experimental benchmarks existing in the literature. This software allows high flexibility of structural configurations and masonry patterns, able to import the geometric model from CAD tools and to define material properties, boundary and loading conditions. Three possible numerical methods for the optimization routines required by the adopted solution procedure are explored with the indication of the most suitable one. Results of the analyses indicate that, especially when thrusting elements, e.g., the static thrust of vaulted structures or thrusting roofs, are present on the unreinforced front wall, the implemented approach involving the stabilizing effects of interlocked walls provides more realistic and reliable performances compared to popular methods. This paper also sets the stage for an extension of implementation to all the possible local mechanisms in masonry buildings, the modelling and design of strengthening interventions with traditional and innovative systems, according to the minimum intervention principle, and to displacement-based analyses.
... Taking into account the suggestion of the Greek code KADET to avoid the gable area for the placement of a control joint, the joint in the top central part of the wall below the pediment was additionally considered [joint U(3)y]. As shown in Figure 6, the control joints included in the models, are located at the positions where the maximum displacements are expected in each direction and thus are critical for the monument's seismic behaviour, as is also proposed in the literature (Lagomarsino, 2015).The capacity curves of the building as resulted by the analysis are presented in Figure 8 and Figure 9. The base shear force is plotted on the vertical axis of the diagrams given as a percentage of the building's self weight, while on the horizontal axis the absolute displacement of the control joint in the direction of the seismic action is given. ...
The Byzantine remains of the three-aisled basilica with a narthex on Jebel Musa, South Sinai, were known to the scholarly world since the 19th century. The architectural survey of the site (1995) and the excavations of the Hellenic Archaeological Mission at South Sinai (1998–9, 2008) identified additional original parts of the church and unearthed its foundations. A detailed study of the thorough survey of the in situ preserved parts of the building and the architectural members found scattered in the surroundings led to a quite precise graphic reconstruction of the original form of the Basilica and a better understanding of its structure and its constructional characteristics.
Based on the graphic reconstruction of the basilica a seismic vulnerability assessment was attempted since both from the structural point of view and from literature sources earthquake seemed the most probable cause for the monument’s destruction. A preliminary numerical linear elastic analysis was carried out, focusing on the structural behaviour under seismic actions, and then pushover analysis was performed to better evaluate the failure mechanisms under lateral loading. The qualitative and quantitative evaluation of the analyses results in comparison with the actual remains of the basilica led to an approximation of the possible failure mechanisms.
Both elastic and pushover analysis results are being presented and compared. The elastic analysis pointed out possible failure mechanism whereas the pushover determined the primary mechanisms in each direction as well as the magnitude of the seismic force in each direction that the structure can withstand with significant deformation (the deformation magnitude requirements was set using the Greek regulatory guidelines for seismic assessment of masonry building). It was pointed out that the long cella walls comport poorly in out of plane actions and suffer significant deformations in a magnitude of seismic force up to 8% of the structure’s permanent loads. In the direction parallel to the long walls the most sensitive part is the west narthex wall that suffers significant deformations in a magnitude of seismic force up to 21% of the structure’s permanent loads. The seismic force for which the pushover analysis predicts the early failure mechanisms is far from the seismic requirement (design seismic forces were calculated using Eurocode 8 guidelines) as low as 60%.
... The key reasons for this are that (i) these limit values do not represent any failure mechanism as defined by other codes, such as NTC ( ) or EN 1998( -3 (2005, and (ii) the limits are not related to geometric properties, loading, or boundary conditions. Several studies have been conducted to identify the damage limit states of historical structures using a multi-scale approach (Lagomarsino and Cattari, 2015;Marino, Cattari and Lagomarsino, 2019;Senaldi et al., 2020), which is primarily based on a comparison of drift values at the macro-element, local, and global levels. Obtaining limits for each scale and hence defining the damage limit states is required. ...
The seismic vulnerability of historical masonry buildings is a significant concern in regions prone to earthquakes. The Turkish Building Code (2018) does not address seismic assessment of historical structures. Implementation of structural engineering on historical buildings in a conventional way is not feasible due to their complex geometry, diverse materials, long-term effects, and imposed damage in previous events. The Guideline for Earthquake Management of Historical Constructions (2017) is commonly used in the engineering practice in Türkiye to assess and retrofit these structures. The use of drift-based damage limits is one method of evaluating vulnerability and developing suitable retrofit strategies without compromising the historical importance of the buildings. Studies have highlighted the importance of defining and quantifying damage in a drift-based approach when it pertains to failure mode dependency, geometry, loading, and boundary conditions. According to the Turkish Guideline, drift limits proposed are independent of masonry behaviour and physical properties, resulting in an inaccurate risk assessment. The purpose of this paper is to examine the reliability of these drift limits by comparing them to values obtained from other codes, guidelines, and masonry pier datasets. By using finite element analysis, a case study of a historical masonry mosque is analysed, emphasizing the importance of considering different deformation capacities for each type of failure mode and incorporating drift limits. Inadequate consideration of the specific failure modes of masonry can lead to incorrect assumptions and unconservative results when performing performance assessments, which may pose a threat to architectural heritage.
... Many of the affected assets by this phenomenon are structures and monuments, possessing cultural values important for society and humanity. To develop effective seismic risk mitigation strategies, it is necessary to develop both new assessment procedures and new retrofit solutions that respect the cultural values and adhere to ICOMOS guidelines [17,18], while being sympathetic and sustainable. The analysis of such buildings is further complicated by uncertainties faced both in terms of material and modelling properties [19,20]. ...
The sympathetic restoration and conservation of built cultural heritage play a significant role in the management and preparedness for future climate scenarios by facilitating adaptive reuse, enhancing cultural resilience, preserving traditional knowledge, and boosting tourism. The importance of restoring damaged heritage sites after an earthquake drew international attention to Nepal after the 2015 Gorka Earthquake. UNESCO established an office in Kathmandu to promote the restoration of tangible and intangible heritage in the area. This included developing structural analyses of buildings with historical and cultural value that due to their nature cannot be intervened with the same methodology as modern buildings. In this paper, the case study of the earthquake-damaged Gopinath temple, is discussed. First, an initial visual inspection phase and the following diagnosis of the structure are discussed. Then, the results from a series of static and dynamic structural analyses performed to determine the safety level of the structure, together with a sensitivity analysis, are presented. A sympathetic intervention proposal capable of increasing the temple safety level and based on the addition of timber plates, has resulted in substantial improvements of the lateral behavior of the structure. The proposed intervention is deemed sustainable and able to increase the resilience of the temple in the face of future hazards.
... Many of the affected assets by this phenomenon are structures and monuments, possessing cultural values important for society and humanity. To develop effective seismic risk-mitigation strategies, it is necessary to develop both new assessment procedures and new retrofit solutions that respect the cultural values and adhere to ICOMOS guidelines [18,19], while being sympathetic and sustainable. The analysis of such buildings is further complicated by uncertainties faced both in terms of material and modeling properties [20,21]. ...
The sympathetic restoration and conservation of built cultural heritage play a significant role in the management and preparedness for future climate scenarios by facilitating adaptive reuse, enhancing cultural resilience, preserving traditional knowledge, and boosting tourism. The importance of restoring damaged heritage sites after an earthquake drew international attention to Nepal after the 2015 Gorka Earthquake. UNESCO established an office in Kathmandu to promote the restoration of tangible and intangible heritage in the area. This included developing structural analyses of buildings with historical and cultural value that, due to their nature, cannot be intervened with the same methodology as modern buildings. In this paper, the case study of the earthquake-damaged Gopinath temple is discussed. First, an initial visual inspection phase and the following diagnosis of the structure are discussed. Then, the results from a series of static and dynamic structural analyses performed to determine the safety level of the structure, together with a sensitivity analysis, are presented. A sympathetic intervention proposal capable of increasing the temple’s safety level, and based on the addition of timber plates, has resulted in substantial improvements in the lateral behavior of the structure. The proposed intervention is deemed sustainable and able to increase the resilience of the temple in the face of future hazards.
... The foremost 10 funding supporters in research on seismic hazards and risk assessment are the National Natural Science Foundation of China, the National Science Foundation (USA), the European Commission, the Horizon 2020 Framework Programme, the National Key Research and Development Program of China, Seventh Framework Programme, Natural Sciences and Engineering Research Council of Canada, Natural Environment Research Council, and U.S. Geological Survey [54][55][56][57][58][59][60][61][62]. The order presented in Table 9 is determined by the overall number of publications. ...
A bibliometric analysis spanning from 2002 to 2022 examines the landscape of seismic hazard and risk assessment research, critical for disaster preparedness in earthquake-prone regions. The study uncovers a substantial increase in related studies, notably surging around 2006. Leading contributors hail from China, the United States, Italy, and the United Kingdom, underlining the global significance of the subject. Common terms in scholarly articles include “seismic hazard”, “seismic risk”, “earthquake”, “vulnerability”, “GIS” (Geographic Information System), and “liquefaction”. While seismic hazards remain the primary focus, a growing interest in risk assessment, particularly for induced phenomena like landslides and liquefaction, is noted. Researchers predominantly assess vulnerability across various structural elements, reflecting a holistic approach to understanding and mitigating the impact of earthquakes on infrastructure and communities. In summary, the bibliometric analysis provides a comprehensive overview of seismic hazard and risk assessment research, highlighting field growth, key research areas, and an increasing focus on risk assessment in response to natural phenomena. The findings offer valuable insights for both academics and practitioners invested in the field’s future development.
... In the last decades, the development of practical and effective tools for the seismic assessment of URM structures became the object of relevant efforts from the scientific community. Numerical modelling is nowadays recognized as the reference quantitative seismic evaluation approach for complex URM buildings, for which qualitative analyses alone are seldom sufficient [108], being also endorsed by building codes [159,160] and international guidelines [98]. Several procedures with varying complexities were made available in the literature, ranging from revisited yet still simplified graphic statics solutions [152,22] and geometry-based [175,55] to more advanced macro- [170,35], meso-(often referred to as simplified micro-modelling as well, see [9,121]) or micro-(or detailed micro-modelling approaches, see [54,204]) scale numerical models typically referring to component-, masonry cell-and joint-level discretization layouts, respectively, as per the widely accepted classification proposed by Lourenço [120], implemented in either continuum (e.g. ...
In the last few decades, discontinuum (or discrete, discontinuous) numerical modelling strategies-i.e. those capable of representing the motion of multiple, intersecting discontinuities explicitly-have become increasingly popular for the structural and seismic assessment of unreinforced masonry (URM) structures. The automatic recognition of new contact points and prediction of large deformations up to complete separation are unique features of discontinuum-based models, making them particularly suitable for unit-by-unit simulations. The adaptation of discrete computational models, primarily used for analyzing rock mechanics and geomechanics problems, to the conservation, structural and earthquake engineering evaluation of URM assemblies is still ongoing, and recent advances in computer-aided technologies are accelerating significantly their adoption. Researchers have now developed fracture energy-based contact models tailored to unreinforced masonry mechanics , explored discontinuum analysis from the mortar joint-to the 3D building-level, combined discrete modelling strategies with analytical or continuum approaches, integrated the latest structural health monitoring and image-based developments into discontinuum-based analysis framework. Concurrently, new and still unsolved issues have also arisen, including the selection of appropriate damping schemes, degree of idealization and discretization strategies, identification of appropriate lab or onsite tests to infer meaningful equivalent mechanical input parameters. This paper offers to the research and industry communities an updated critical appraisal and practical guidelines on the use of discontinuum-based structural and seismic assessment strategies for URM structures, providing opportunities to uncover future key research paths. First, masonry mechanics and discontinuum-based idealization options are discussed by considering micro-, meso-and macro-scale modelling strategies. Pragmatic suggestions are provided to select appropriate input parameters essential to model masonry composite and its constituents at different scales. Then, discontinuum approaches are classified based on their formulation, focusing on the Distinct Element Method (DEM), Applied Element Method (AEM) and Non-Smooth Contact Dynamics (NSCD), and an overview of primary differences, capabilities, pros and cons are thoroughly discussed. Finally, previous discontinuum-based analyses of URM small-scale specimens, isolated planar or curved components, assemblies or complex structures are critically reviewed and compared in terms of adopted strategies and relevant outcomes. This paper presents to new and experienced analysts an in-depth summary of what modern discontinuum-based tools can provide to the structural and earthquake engineering fields, practical guidelines on implementing robust and meaningful modelling strategies at various scales, and potential future research directions.
... This is especially important for structures designed and constructed using ancient techniques, such as the stone temple at hand, not covered by modern design standards (Cigada et al. 2017). Masonry heritage structures are especially valuable from a cultural viewpoint and particularly important to preserve, hence they have attracted strong research attention regarding their seismic performance (Casapulla, Argiento, and Maione 2018;D'Ayala and Lagomarsino 2015;Lagomarsino and Cattari 2015;Pardalopoulos and Pantazopoulou 2017;Torelli et al. 2020). It is also recognized that these structures have unique failure modes under high frequency vibrations (e.g. ...
The BAPS Hindu Mandir, recently constructed in Abu Dhabi, UAE, is a complex unreinforced stone masonry structure built from thousands of sculpted sandstone and marble pieces employing ancient Indian techniques called Shilp Shastra. The entire structure is substantially large with a footprint size of 5,100 m 2 and unique so that it is not covered by modern seismic design standards. Its performance was verified by conducting dynamic field tests presented herein. The most vulnerable substructure was identified based on both engineering judgement and modal analysis of the entire structure employing a detailed 3D finite element model, which was validated via the field experiments. A "local" model was developed for the identified vulnerable substructure which significantly reduced model complexity and allowed to overcome computational limitations. Based on the response of the local model, the relative importance of the sensor locations was determined via a Displacement Index method in addition to a reduction of the total variance of spectral accelerations using conditional probability theory. Through this approach, a methodology for selecting the optimal sensor placement with application on the complex unreinforced stone masonry Hindu Mandir is proposed. ARTICLE HISTORY
... The most vulnerable parts of the structure were identified using the N2 method developed by Fafjar and Fischinger in 191 1988 [110] and later implemented in Eurocode 8 [111], among other standards. The N2 method has been applied in 192 the numerical analysis of some complex structures obtaining adequate responses in terms of collapse mechanisms, 193 verification of seismic performance through the evaluation of the displacement demand on the capacity curve [112] 194 [113] walls of the nave. Additionally, there is no record of PGA in the area. ...
... Seismic assessment of a monument is based on the following three main steps (Lagomarsino and Cattari 2015): ...
Historical monuments portray the architectural heritage and cultural wealth of a
civilization. They are symbols of pride and a gateway to our past. Therefore it is of
paramount importance that these monuments be preserved for future generations.
Foremost symbol of Lucknow Awadhi architecture, Rumi Darwaza is an 18th century
gateway structure characterized by a half spherical dome resting on half octagonal plan and further supported by an arch. The masonry structure, built using thin burnt clay bricks (Lakhauri) and lime-crushed brick aggregate (surkhi) mortar, has developed
major cracks in the arch due to natural aging and other environmental factors. Past
earthquakes in India have highlighted the poor seismic performance of our monuments.
Seismic assessment of historic monuments needs to be carried out to evaluate their
structural response and draw out retrofitting plans to ensure their longevity.
To assess the seismic performance of Rumi Darwaza, dynamic characteristics, such as
natural frequencies, mode shapes and damping ratios, are required for realistic
numerical simulation which have been obtained from field vibration tests. Laboratory
experiments were conducted to characterize the mechanical properties of Lakhauri
bricks and lime surkhi mortar, as well as masonry prisms. A detailed Finite Element
(FE) model was developed to understand the structural behaviour under gravity and
seismic loads. Dynamic characterization results are seen to match closely with analytical predictions validating the FE model. Response spectrum analysis showed the stiffening arch at the open face of half dome to be the critical structural element with high tensile stresses at the same locations where damages have been observed in the structure. Two strengthening techniques using latticed structure of concrete filled hollow steel tubes to support the dome arch from the inside have been proposed to reduce its vulnerability for seismic forces.
... Monumental structures and environmentally valuable structures can be classified as immovable cultural assets that need to be protected. In order for an immovable to gain a cultural asset value, it must have a unique value and this value must give the immovable certain qualities [12]. The protection of cultural assets is of international importance. ...
Restoration works in historical buildings, which have gained importance in Türkiye in recent years, have unique risks in terms of occupational safety. Employees in this sector are exposed to many different risks during the restoration of historical building projects, and ensuring occupational safety is an important problem for the sector. In order to find a solution to this problem, a comprehensive examination of historical building projects was made in terms of occupational safety during the restoration process. Within the scope of the study every stage of the three different restoration projects was examined in terms of occupational safety. In line with this research, job safety analysis was performed by dividing the steps in the restoration projects into groups. The risks in the construction sites were determined and precautions were presented to eliminate or reduce these risks. As a result, the risks that may occur during the restoration phase of a historical building are shown in detail together with the prevention methods. It is expected that if the stakeholders of restoration projects integrate the information presented into their occupational health and safety systems, it will contribute to the improvement in the processes and there will be a decrease in the frequency of work accidents.
... This aspect could allow the local authorities to prioritize the rehabilitation works not only based on the highest structural vulnerability, but also based on the highest cultural value of the buildings. The preservation of the most important architectural heritage of the city, is in accordance with the European guidelines for the preservation of the cultural heritage assets [14] and also with the UNESCO program for the cultural landscape [15]. ...
... The global seismic behaviour of the tower has been assessed through NLSA. This method has been widely used for this purpose [29] and suggested in the Eurocode 8 [30]. Due to the unsymmetric configurations caused by the irregular distribution of the ramps and the openings, the NLSA has been conducted in both directions (X and Y). ...
... towers, minarets etc.) and massive structures prevailing local failure of masonry (e.g. fortresses, city walls etc.) may require different approaches such as macro block modeling, discrete element modeling, structural elements modeling and continuous constitutive law modeling for in detail seismic vulnerability assessment investigation [6]. However, the most inclusive choice for differently characterized masonry structures is Finite Element Modeling. ...
This study aims at creating an advancement guideline for a software which can be used for seismic vulnerability assessment of historic masonry structures by revealing the results of an experience related to the macro modeling of a historic masonry building. The case study structure is Bergama Bedesten (15th-16th centuries) located in Bergama, İzmir, Turkey. ANSYS software is used for the Finite Element Modeling of the structure. The seismicity at its location is determined and the structural response under lateral loads is obtained together with the dynamic characteristics. Mesh design, component creation according to the used material change in structural elements, contact surface identification, the arrangement of the stress scales, and result interpretation are realized. For these stages, the challenges are discussed with the solutions. The advantageous aspects of the software are explained. For the challenges, in mesh design, the ineffectiveness of cartesian method for some elements was detected and tetrahedrons method was chosen. In contact surface identification, the overlapping portions of structural components could not be detected by the software exactly, so the manual surface separation was realized. In the stress level interpretation, the lack of assignment for material limit strength values to the analysis scale was experienced and the addition of limit values was carried out. The scale also needs manual arrangement for the increase of interval numbers of stress values to emphasize vulnerable zones. This flexibility of scale to be arranged can be seen as an advantage, as well. The 3d section and axonometric view creation provide the presentation of stress changes at inner and outer surfaces of the structure which is another positive side.
... Masonry construction is a widespread structural typology, encompassing a wide array of different bonding patterns and accounting for a large percentage of the inventory of existing structures, such as vernacular and monumental buildings and infrastructure. Therefore, the accurate prediction of the behaviour of masonry structures under mechanical loading caused by tectonic [21] or induced [16] earthquake action or differential settlement [14] has important financial, social and cultural implications. ...
... These approaches represent the more conventional and established methodologies well researched and recognized internationally. Giordano et al. [107] use a novel mechanical-based closed-form solution for the out-of-plane seismic assessment of masonry school buildings in combination with a modified version of the Capacity-Spectrum-Method that can be used to evaluate building responses under earthquakes and plots acceleration versus building displacement [113,114]. Additionally, different studies utilize approaches such as calculating damage ratios based on various building performance measures [109] or Dynamic Building Simulation software [111,112,115]. Besides, there is one study [105] that uses artificial intelligence (neural networks) to achieve quantification and one that integrates various GIS tools in its elaboration [103]. ...
Supplementary material related to this article can be found online at https://doi.org/10.1016/j.ijdrr.2023.103967.
Schools and other educational institutions are important pillars for the well-being of society. However, education continuity is increasingly threatened by negative influences such as disasters and acts of violence. An important tool to ensure the safety of educational institutions is the development of a methodology to measure education system resilience. To advance the development of such a methodology, a scoping review is conducted to identify current quantification methodologies for education system resilience and to highlight promising research directions. The procedure of the scoping review is developed following the specifications of Joanna Briggs Institute Reviewer’s Manual in accordance with the PRISMA-ScR-checklist. Quantitative psychological approaches are excluded for reasons of consistency of the resilience conceptualization. Resulting from a total of 2528 records, 31 are involved in data synthesis comprising (case) studies from the continents of Asia, North and South America, as well as Europe. While the scoping review started broad, a predominance of building-related studies and natural hazards was identified. Furthermore, the methodologies mainly differ along three dimensions: scope, level of detail, and complexity. However, no methodology achieves high performance on all dimensions. Altogether, it can be recognized that all methodologies possess individual advantages that complement each other well. Therefore, a framework for combining the different quantification methodologies is proposed to achieve the most accurate and comprehensive quantification possible. Considering only limited available resources, an adaptation of the proposed methodology to the educational institution’s and its community’s social, geographic, and further circumstances is essential to allow for a prioritization of quantification components.
... Typological analyses have indeed been widely implemented abroad to similar ends to assess the seismic attributes of regional building typologies [21], for use in urban seismic risk mitigation [22] or local personal risk [23]. Typological analyses have also been utilized abroad to inform mechanical characterization, seismic assessment and retrofit design [24,25]. The typological analysis herein conducted employs archival research and analysis of building inventories to describe the prominent structural features of old industrial URM buildings in Eastern Canada and their evolution. ...
Old industrial unreinforced masonry (URM) constructions comprise a significant portion of the existing building stock in Eastern Canada. These complex yet still under-researched structural systems have been increasingly targeted for adaptive reuse projects in recent years. Although repurposing existing edifices is identified by provincial legislation as the way forward to preserve architectural heritage and maximize sustainability, the 2020 National Building Code of Canada requires old buildings undergoing major renovations to be seismically evaluated as modern ones. Despite the vulnerability of old industrial URM buildings to earthquakes, scarce knowledge and lack of ad-hoc seismic assessment and upgrading guidelines local practitioners have often translate in oversized retrofits or demolitions. Such invasive interventions pose a serious threat to Eastern Canada’s built environment. This research uncovers recurrent structural characteristics of Eastern Canada’s old industrial URM buildings, vital yet presently missing data for enabling their holistic seismic assessment, upgrading and reuse. To inform onsite research and testing in the framework of a larger research program at McGill University, a comprehensive archival study was conducted and herein presented that consolidates existing building inventories to identify recurrent construction techniques, materials and key architectural features in different historical periods. Produced outcomes enabled us to classify recurrent structural typologies from an earthquake engineering perspective, as well as to identify a critical buildings representative of Eastern Canada’s trends in Montréal, where most assets are located. Results from our pioneering research will constitute a solid foundation on which to inform local engineers and develop informed seismic evaluation and risk mitigation strategies.
... For example, in this field is included the GEM [13] which collects resources for transparent assessment of earthquake risk, facilitating their application for risk management around the globe, which can be implemented through open-source software and GIS systems. Among these, numerous are those that work at the urban scale, with a particular focus on historic centers, such as [14] [15] [16]. ...
The Geographic Information System (GIS) is increasingly used in the scientific field for the management and conservation of built heritage. The present paper proposes a GIS methodology for the collection and analysis of the data related to the seismic risk and for the management of damage prevention interventions on masonry architectural assets, based on the empirical approach. Indeed, starting from the observation of real damage, that occurred after the recent Italian earthquakes, it was possible to collect a large amount of data, which has been organized and queried using the GIS tool. This methodology was tested on two different architectural typologies, designing two different databases: protruding elements and fortified architectures. This proactive tool allowed both the correlation between constructive features and damage mechanisms, through statistical analyses, and the comparison of the damage levels with the seismic action of the site, through the introduction in the GIS of the shake-maps, to identify the empirical fragility curves, which represent the expected damage, depending on the seismic action. Then, these functions were applied to an area without earthquake damage, using the seismic actions provided by the hazard map. This methodology allowed the identification of the assets most at risk in case of future seismic events, on a large scale. Knowing the vulnerabilities of the heritage means being able to act preventively, with planned conservation strategies, optimizing the management of economic resources, and minimizing invasive interventions.KeywordsArchitectural HeritageSeismic RiskGIS DatabaseFragility Curves
... to the first family, depending on the formulation adopted and the interaction between the different masonry components. Some of these approaches are interface element-based approaches, contact-based approaches, textured continuum-based approaches, block-based limit analysis approaches, and extended finite element approaches [12][13][14][15][16][17]. Some of these approaches rely on the definition of specific laws to reproduce the masonry response, for example, the traction separation law for cohesive elements [18]. ...
Considering the high vulnerability of existing masonry buildings, which often have strategic or cultural value, professionals and specialized engineers are frequently required to model complex historical buildings. The approaches proposed by National Building Codes may not always be suitable for such cases, but more detailed approaches are necessary, relying on FEM continuum modeling and inelastic constitutive law. There are many constitutive laws proposed in the literature that allow us to accurately reproduce the mechanical behavior of masonry. However, they require the identification of several parameters that are not easy to determine. In this study, a sensitivity analysis of the parameters of a nonlinear constitutive law very popular for masonry modeling (the “Concrete Damage Plasticity—CDP” model) is conducted, considering literature tests of masonry panels under shear stress as the benchmark. The aim is to assess the influence of the main parameters of the model and compare them to one of the more commonly used Mohr–Coulomb failure criteria.
... For regional assessments, methods such as vulnerability index method [4] can be adopted. In contrast, a more accurate individual building seismic assessment can be done by using numerical modelling techniques [5]. ...
... To assess the pinnacles' ultimate behavior, nonlinear kinematic analyses adopting a macro-block model (MBM) approach are carried out by exploiting the MB-Perpetuate Fig. 8 Out-of-plane seismic assessment of pinnacles. a Definition of the bi-linear capacity model and identification of DL thresholds; b intersection between the capacity curve of the system and scaled floor spectra to assess the peak ground acceleration a g associated with each LSs code [51], a software developed in the framework of the Perpetuate Project [52]. The seismic assessment is based on the displacementbased approach illustrated in [53], whose reliability has been validated in [54] through the comparison of results achieved from nonlinear dynamic analyses. ...
Post-earthquake damage surveys systematically highlight the seismic vulnerability of monumental structures, calling for simple assessment procedures to address the design of effective retrofitting interventions. The structural complexity characterizing monumental structures, however, makes a reliable prediction of their seismic response a relevant challenge of engineering interest. Ambient vibration tests (AVTs) provide valuable support to achieve such a task, improving the knowledge of the actual dynamic behavior of the structure and, consequently, the reliability of the seismic assessment. In this context, the paper illustrates the integration of AVTs outcomes with the evaluation of the seismic performance of historic masonry structures by presenting the comprehensive application to a case study, the bell tower of the Saint Lawrence’s Cathedral in Genoa, Italy. The research combines the assessment of the global seismic response of the tower, investigated through a simplified mechanical model, with the local verification of the pinnacles placed at its top, referring to a displacement-based approach on a macro-block model. An extensive ambient vibrations measurement campaign carried out in May 2020 allowed for a comprehensive operational identification of the bell tower and its pinnacles, clarifying the ongoing dynamic interaction with the main body of the church. This valuable information was successfully employed, first, to accurately reproduce the actual constraint conditions induced by the church on the bell tower, a determining factor in the modeling of its global seismic response and, second, to reliably quantify the seismic amplification caused by the tower filtering effect to be used as the seismic input for the local verification of the pinnacles.
El objetivo principal de este trabajo es aplicar el método de los elementos finitos para el modelado del sector de Abd’ al-Rahman I de la Mezquita-Catedral de Córdoba. Este edificio es de un gran valor cultural y patrimonial. Por ello, fue declarado Patrimonio de la Humanidad por la UNESCO en 1984. El monumento se encuentra al sur de la península ibérica. Este área se caracteriza por una actividad sísmica moderada. Debido a ello, de cara a su preservación y al análisis de su seguridad, es importante analizar su comportamientos estructural y sísmico. En este trabajo, se ha desarrollado un modelo en 3D en el software abierto OpenSees. Para ello, se han realizado ensayos no destructivos sobre el edificio. Para el análisis de su comportamiento, se han realizado análisis estáticos verticales y horizontales (tipo pushover). Como resultado, se ha obtenido que el edificio presenta un peor comportamiento sísmico en la dirección perpendicular a las arcadas
The typological analysis conducted in the companion paper (Davis and Malomo, 2024b) is further expanded within this work through the critical analysis of a new extensive building database specifically conceived for old industrial masonry buildings in Eastern Canada. The identification of recurrent unreinforced masonry (URM) building archetypes in this low-to-moderate seismic region is essential to decrease uncertainties currently prevalent in the analysis of local old URM structures, often targeted for adaptive reuse. The database assembled herein comprises various heritage designated buildings across Eastern Canada, and was compiled harmonizing existing repositories at the federal, provincial and municipal level with an unprecedented focus on structural features. The characteristics of these resources are quantitatively analyzed and applied to a case study of the city of Montréal, one of the most important industrial centers in 19 th and 20 th century Canada. Outcomes from this study will guide practitioners and researchers involved in the structural and seismic assessment and retrofit of old industrial URM constructions, enable more and less invasive rational retrofit designs, and inform the new Existing Structures provisions to be included in the 2030 National Building Code of Canada.
Industrial unreinforced masonry buildings (URM) are an important part of the existing building stock in Eastern Canada, a region characterized by high-frequency and low-to-moderate magnitude earthquakes. Despite their inherent vulnerability to earthquakes, these non-engineered buildings are being increasingly targeted for reuse purposes in many densely populated cities in the region. A lack of knowledge of local construction techniques, materials and architectural types paired with limited information of their characteristics leads seismic retrofits to be even more disruptive than usual. Often such seismic retrofits result in expensive and complex designs or avoidable partial demolitions. Typological analysis is utilized in this work to identify local recurrent building archetypes and technologies through archival resources, as well as their evolution through time, as a first step to addressing the lack of information about the structural characteristics of this building type. Results from this study inform subsequent critical and more quantitative investigations conducted in the companion paper (Davis and Malomo, 2024), where the first building database focussing on Eastern Canada’s old industrial URM constructions is presented and comprehensively reviewed. This research will enable engineering practitioners and applied researchers to decrease epistemic uncertainties and confidence factors in their structural/seismic assessments, vital to develop rational retrofits.
This paper presents the seismic risk assessment of the southern section of the cloister of Lisbon's Patriarchal Cathedral, based on the analysis of the disaggregated response, using pushover analyses with refined finite element models that include non-linear joints between stone masonry elements. This analysis corresponds to the evaluation of the deformed configurations considered relevant for local collapse mechanisms of the structure. The return periods of the seismic action that induce the activation of various limit states are determined in three different phases of the project, started in 2018 and being now completed, as well as the corresponding probabilities of exceedance of these limit states and compared with reference values from modern regulations. A strengthening intervention was then designed to mitigate the risk in the
most vulnerable elements.
The planning of interventions aimed at preserving the built heritage of inner areas is a complex process due to the fragility of these contexts. It should stem from adequate knowledge to support the recognition of qualities, resources, and potentials, and the reinterpretation of residual values. From the perspective of an axiological approach to the built heritage, it is possible to foster the resemantization of such values based on a rigorous cognitive model. This research proposed a cognitive model of the built heritage of the historic neighbourhood of Granfonte in Leonforte (Enna). The knowledge model, developed in Excel, has a hierarchical type of structure characterized by domain, classes, properties, and the attribution of values to properties. The approach makes it possible to execute queries that arise from specific relationships between classes. In this study, we developed both simple queries to measure the percentages of certain characteristics of the building units and complex queries for the estimation of aggregate indices to define the degree of transformation and loss of integrity and degradation of the building units or to identify those most exposed to the risk of ruination and contagion. The proposed model can be framed within the framework of ontologies supporting structured heritage knowledge.
Ancient Chinese stone arch bridges are different from ancient Western stone arch bridges in terms of bridge form, bridge structure, bridge material and construction technique. In order to clarify the structural safety status of this type of stone arch bridge and provide a scientific basis for subsequent conservation, an appropriate quantitative evaluation method of structural safety status is proposed for the ancient nine-hole stone arch bridges. Taking the typical nine-hole stone arch bridge, Putang Bridge, as an example, first, a structural safety evaluation system for the bridge was built up according to the bridge form and bridge structure. Then, an improved analytic hierarchy process method based on component importance analysis was proposed to obtain the weight coefficients of the main structural components of the bridge. Finally, the structural safety status of this bridge was quantitatively evaluated with the proposed method. The results can provide a reference for the quantitative evaluation of the structural safety status of ancient nine-hole stone arch bridges.KeywordsStone Arch BridgesStructural Safety StatusQuantitative AssessmentPutang Bridge
The present paper addresses the development of large-scale vulnerability models for masonry buildings with seismic retrofitting interventions in the Abruzzo region, Italy. The proposed work is the result of an Italian Research Project developed within a cooperative agreement between the Italian Network of University Laboratories of Seismic and Structural Engineering (ReLuis) and the Department of Civil Protection (DPC). The goal is to assess the seismic vulnerability at the urban scale through analytical models accounting for the out-of-plane behavior of masonry structures and to evaluate the vulnerability variation between the “as-built” and “retrofitted” configurations. Thanks to an automated procedure developed by the Authors, archetype masonry buildings are first identified to limit the number of buildings object of analyses. These archetypes are defined according to specific parameters selected from the Cartis form, an Italian tool that collects typological-structural information of the buildings present throughout the national territory. Afterwards, based on information retrieved from the literature and on the effectiveness shown during earthquakes, an exemplary seismic intervention is selected and applied to representative buildings with the aim of quantifying their improved seismic behavior. The results obtained from this investigation are shown by means of fragility curves and can be of great support in the definition of cost-effective risk mitigation strategies, allowing to quantify benefits and costs of possible interventions at the territorial scale.KeywordsVulnerability modelsArchetype buildingsCARTIS formMasonry buildingsRetrofit interventions
For historical structures in seismic regions, earthquake often presents one of the highest risks for their damage or, in extreme events, even collapse [1]. In historic structures, artistic assets attached to the structural elements are often of great importance and value but are however commonly even more vulnerable to earthquakes since they exhibit more damage already in less strong, more frequent seismic events. Seismic performance-based assessment (PBA) with nonlinear analysis methods offers a possibility to evaluate the earthquake hazard levels in correspondence to appointed performance limits associated with structural and non-structural damage of interest [2, 3]. To conduct such analyses, high level of knowledge of the analysed building is required as well as in-depth, experimentally supported knowledge of the seismic behavior of the built-in materials and structural and non-structural elements.Since very few experimental tests on the seismic performance of artistic assets attached to the walls exist [4], the paper presents detail results of experimental study where damage of plasters attached to stone masonry walls under in-plane lateral loading was studied. The results served to conduct a deterministic PBA of an actual historical heritage building, a renaissance mansion, where besides structural damage also damage on frescoes attached to the walls is considered.The analysis shows that the analysed building would sustain a 177 years return period earthquake. It also shows that the maximum ground accelerations for performance levels considering significant damage of frescoes are rather high compared to performance levels related to structural elements and that the frescoes would not be destroyed prior collapse of the building due to flexural damage mechanism of the walls to which they are attached.KeywordsCultural Heritage Masonry BuildingPerformance-Based Seismic AssessmentPerformance LevelsExperimental Cyclic Shear TestsArtistic AssetsDamage Limits
This manuscript discusses some preliminary results on the structural and the seismic performance of the Mosque-Cathedral of Cordoba, a UNESCO World Heritage. The area is characterized by a moderate seismic hazard. The building was built from the 8th to the 16th century and it has undergone several transformations. Owing to the complexity of the building, this work has focused on the assessment of the Abd al-Rahman I sector, which is the most aged part of the complex. For that, first, a 3D numerical finite element model of the sector has been done in the OpenSees framework and calibrated. To do so, an experimental non-destructive campaign has been carried out. Second, the model has been used to evaluate the structural behaviour, under vertical and horizontal loads, considering different scenarios. Finally, the crack patterns and the seismic safety have been obtained. The results showed that the numerical damage obtained for the gravitational loads is in good agreement with the data collected from the in situ surveys. Also, particular attention should be paid to the cymatiums, as they are the most demanded part of the system. Regarding its seismic performance, the building presents a higher capacity in the direction of the arcades. For the seismic demand, slight damage is expected in both principal directions of the building, which could be easily repaired. Damage concentration is expected in the contact between the perimetral wall and the arcades. This work has expanded the study of the features of the Mosque-Cathedral of Cordoba to the structural and seismic analysis with advanced numerical FE computing, which has not been done to date. To the authors’ knowledge, this is the first time that a macro-modelling approach with solid elements is presented for the seismic assessment of heritage buildings using the OpenSees framework. The methodology to do so is also presented. Apart from showing how advanced numerical analyses can provide useful information to assess the existing damage on monumental buildings, this work aims at contributing to the assessment of the vulnerability and the safety of one of the most emblematic mosque-like buildings of the world.
In Europe, the reference document for the seismic assessment of buildings is the Eurocode 8-Part3, whose first draft goes back to 1996 and, for what concerns its safety format, has strong similarities with FEMA 276. Extended use of this document, especially in Italy after the 2009 L'Aquila earthquake has shown its inadequacy to provide consistent and univocal results. This situation has motivated the National Research Council of Italy to produce a document of a level higher than the one in force, characterized by a fully probabilistic structure allowing to account for all types of uncertainties and providing measures of performance in terms of mean rates of exceedance for a selected number of Limit States (LS). The document, which covers both reinforced concrete and masonry buildings, offers three alternative approaches to risk assessment, all of them belonging to the present consolidated state of knowledge in the area. These approaches include, in decreasing order of accuracy: (a) Incremental dynamic analysis on the complete structural model, (b) Incremental dynamic analysis on equivalent SDOF oscillator(s), (c) Non-linear static analysis. In all three approaches relevant uncertainties are distinguished in two classes: those amenable of description as continuous random variables and those requiring the set-up of different structural models. The first ones are taken into account by sampling a number of realizations from their respective distributions and by associating each realization with one of the records used for evaluating the structural response, the latter by having recourse to a logic tree. Exceedance of each of the three considered Limit States: Light or Severe damage and Collapse, is signaled by a scalar indicator Y, expressing the global state of the structure as a function of that of its members, taking a value of one when the Limit State is reached. For the first two LS's, which relate to functionality and to economic considerations, the formulation of Y is such as to leave to the owner the choice of the acceptable level of damage, while for the Collapse LS the formulation is obviously unique. An application to a real school building completes the paper.
A global dataset of more than 3,000 ground motion records from 536 sites from Greece, Italy, Turkey, USA and Japan is compiled and used to propose code-oriented elastic acceleration response spectra and soil amplification factors for a new site classification system, which, besides the classical geotechnical parameters NSPT,Su and PI, uses also the fundamental period of the site, the thickness of soil deposits and the average shear wave velocity to the seismic bedrock, instead of Vs,30. We propose a new classification system with the associated amplification factors and normalized response spectra for two seismicity levels, i.e. Ms≤5.5 and Ms>5.5. Uncertainties in the estimation of soil amplification factors are captured using a logic-tree approach, which allows the efficient use of alternative models and methods. The aim of this work is to improve the present EC8 soil classification. The effectiveness of the proposed classification system is compared to that of EC8 classification system using an error term, which represents the average dispersion of data within all categories of a given classification scheme. Error terms for the new classification system are lower than the error terms for EC8 classification system at all periods.
The preservation and valorisation of architectural heritage are becoming more and more a major social and economic issue in many countries. This implies, of course, that a “minimum accepted level” of structural safety is to be ensured of historical construction typologies: several “new challenges” to structural engineers, in consideration of the original structural consistency of Cultural Heritage buildings, frequently exposed to severe environmental hazards (like earthquake). Problems range from the definition and choice of the “conventional” safety level, to the methodologies that can be used to perform reliable structural analyses and safety verifications – as modern ones are frequently not suitable for the construction under consideration – and to the selection, design and execution of appropriate materials and interventions techniques aimed to repair and strengthen the
built heritage while preserving its cultural, historic, artistic values. Many efforts have been dedicated in the recent past to make specific tools, to appropriately tackle the above mentioned problems, available to practitioner engineers and architects: new generations of codes and codes of practice are now also available, specifically for historic constructions. A short review of all the mentioned aspects is presented in the paper, making specific reference to research activities, practical applications and to the recent evolution of codes and guidelines.
The increasing interest in performance-based earthquake engineering has promoted research on the improvement of hazard-consistent seismic input definition and on advanced criteria for strong motion record selection to perform nonlinear time history analyses. Within the ongoing research activities to improve the representation of seismic actions and to develop tools as a support for engineering practice, this study addresses the selection of displacement-spectrum-compatible real ground motions, with special reference to Italy. This involved (1) the definition of specific target displacement spectra for Italian sites, constrained-both at long and short periods-by results of probabilistic seismic hazard analyses; (2) the compilation of a high-quality strong ground motion database; and (3) the development of a software tool for computer-aided displacement-based record selection. Application examples show that sets of unscaled, or lightly scaled, accelerograms with limited record-to-record spectral variability can also easily be obtained when a broadband spectral compatibility is required.
Vulnerability assessment of masonry historical monuments relies on the accurate assessment of their real structural and foundation conditions, which is always a very difficult and challenging task to determine. Ambient noise measurements are among the non-destructive field techniques, which can provide useful information regarding the structural integrity, the dynamic response characteristics of the structure and the dynamic properties of the foundation soil. The performance-based design approach developed in the research project PERPETUATE for the vulnerability assessment of monuments uses all this information in a cost efficient way. Moreover, validation of the whole methodology has been made on several monuments in the Medieval City of Rhodes. To illustrate the use of ambient noise measurements in the frame of PERPETUATE methodology, we performed a number of ambient vibrations measurements on three selected monuments in the Medieval City of Rhodes (Greece) and the surrounding soil. The aim was to identify the dynamic characteristics of the selected structures and the dynamic properties of foundation-soil where these structures are founded. The Frequency Domain Decomposition technique is adopted for ambient modal identification using ARTeMIS software and the continuous wavelet transformation for calculating the wavelet energy to compare it with the pathology pattern of a typical masonry wall. The dynamic properties of the foundation soil, in terms of shear-wave velocity, were also explored using the Spatial Autocorrelation Coefficient method. The goal of the ambient noise measurement performed herein is to better simulate the complex masonry structures in view of estimating their vulnerability using the PERPETUATE methodology and support rehabilitation decisions. The improvement of the initial numerical model using the results of the ambient vibrations measurements illustrates the usefulness of the approach and provides some helpful practical guidelines.
In this paper we propose reduction factors accounting for the decrease of stiffness
of monumental masonry foundations due to aging, weathering, or other deteriorating effects. The proposed reduced stiffness values can be readily used in finite element structural analysis software in the framework of performance-based assessment, representing linear elastic springs at the foundation level. These springs account for foundation-soil system flexibility and soil-foundation interaction (SFI) at low-frequency vibrations. Accordingly, we propose a procedure to reduce monumental masonry foundation-wall stiffness from the rigid-footing assumption, with respect to the relative stiffness between the foundation and the soil. The proposed procedure is applied to the historical structure Arsenal De Milly in the Medieval City of Rhodes, where period elongation and ductility increase are highlighted, because of SFI and foundation flexibility
The assessment of historical elements at risk from earthquake loading presents a 10 number of differences from the seismic evaluation of modern structures, for design or retrofitting 11 purposes, which is covered by existing building codes, and for the development of fragility curves, 12 procedures for which have been extensively developed in the past decade. This article briefly 13 discusses: the hazard framework for historical assets, including a consideration of the appropriate 14 return period to be used for such elements at risk; the intensity measures that could be used to describe 15 earthquake shaking for the analysis of historical assets; and available approaches for their assessment. 16 We then discuss various unique aspects of historical assets that mean the characterisation of 17 earthquake loading must be different from that for modern structures. For example, historical buildings 18 are often composed of heterogeneous materials (e.g. old masonry) and they are sometimes located 19 where strong local site effects occur due to: steep topography (e.g. hilltops), basin effects or 20 foundations built on the remains of previous structures. Standard seismic hazard assessment 21 undertaken for modern structures and the majority of sites is generally not appropriate. Within the 22 PERPETUATE project performance-based assessments, using nonlinear static and dynamic analyses 23 for the evaluation of structural response of historical assets, were undertaken. The steps outlined in 24 this article are important for input to these assessments. 25 Keywords Seismic hazard assessment, site effects, intensity measures, fragility curves, historical 26 buildings, cultural heritage assets, monuments 27 1. Introduction 28 29 As for modern structures, an evaluation of the seismic vulnerability of historical elements at risk
The paper presents the damage and typological classification for the cultural heritage asset proposed in the PERPETUATE Project funded by the Seventh Framework Programme – Theme ENV.2009.3.2.1.1. The driving ideas of the project are: i) adoption of a performance-based approach for the evaluation of seismic safety of cultural heritage assets and the design of strengthening interventions; ii) identification of proper safety levels considering both conservation and safety issues; iii) minimization of strengthening interventions through increasing knowledge and improving modelling tools. Performance Based Assessment methodology is based on the fulfilment of some target performance levels in correspondence to predefined seismic actions. It generally uses pushover analysis and verification by the capacity spectrum method. In order to define reliable models for pushover analysis and criteria for the performance levels, a classification of both architectonic and artistic assets is proposed in the paper, by considering the corresponding seismic damage modes. On the one hand, such classification allows us to identify the more reliable mechanical models to be used in the description of the seismic response of the different types of buildings and artistic assets; on the other hand, it allows us to define reliable damage variables related to each type of building and main elements of the construction.
The preservation and valorisation of architectural heritage are more and more becoming a major social and economic issue in many countries. This implies of course that a “minimum accepted level” of structural safety is to be ensured to historical construction typologies: several “new challenges” to structural engineers, in consideration of the original structural consistency of Cultural Heritage buildings, frequently exposed to severe environmental hazards (like earthquake).
Problems range from to the same definition and choice of the “conventional” safety level, to the methodologies that can be used to perform reliable structural analyses and safety verifications – as modern ones are frequently not suitable for the construction under consideration – and to the selection, design and execution of appropriate materials and interventions techniques aimed to repair and strengthen the built heritage while preserving its cultural, historic, artistic values.
Many efforts have been dedicated in the recent past to make specific tools, to appropriately tackle the above mentioned problems, available to practitioner engineers and architects: new generations of codes and codes of practice are now also available, specifically for historic constructions.
A short review of all the mentioned aspects is presented in the paper, making specific reference to research activities, practical applications and to the recent evolution of codes and guidelines.
The concept of designing structures to achieve a specified performance limit state defined by strain or drift limits was first introduced, in New Zealand, in 1993. Over the following years, and in particular the past five years, an intense coordinated research effort has been underway in Europe and the USA to develop the concept to the stage where it is a viable and logical alternative to current force-based code approaches. Different structural systems including frames, cantilever and coupled walls, dual systems, bridges, wharves, timber structures and seismically isolated structures have been considered in a series of coordinated research programs. Aspects relating to characterization of seismic input for displacement-based design, and to structural representation for design verification using time-history analysis have also received special attention. This paper summarizes the general design approach, the background research, and some of the more controversial issues identified in a book, currently in press, summarizing the design procedure. perceived in terms of simple mass-proportional lateral forces, resisted by elastic structural action. In the 1940's and 50's the influence of structural period in modifying the intensity of the inertia forces started to be incorporated into structural design, but structural analysis was still based on elastic structural response. Ductility considerations were introduced in the 1960's and 70's as a consequence of the experimental and empirical evidence that well- detailed structures could survive levels of ground shaking capable of inducing inertia forces many times larger than those predicted by elastic analysis. Predicted performance came to be assessed by ultimate strength considerations, using force levels reduced from the elastic values by somewhat arbitrary force-reduction factors, that differed markedly between the design codes of different seismically-active countries. Gradually this lead to a further realization, in the 1980's and 90's that strength was important, but only in that it helped to reduce displacements or strains, which can be directly related to damage potential, and that the proper definition of structural vulnerability should hence be related to deformations, not strength. This realization has lead to the development of a large number of alternative seismic design philosophies based more on deformation capacity than strength. These are generally termed " performance-based" design philosophies. The scope of these can vary from comparatively narrow structural design approaches, intended to produce safe structures with uniform risk of damage under specified seismicity levels, to more ambitious approaches that seek to also combine financial data associated with loss-of-usage, repair, and a client-based approach (rather than a code-specified approach) to acceptable risk. This paper does not attempt to provide such ambitious guidance as implied by the latter approach. In fact, it is our view that such a broad-based probability approach is more appropriate to assessment of designed structures than to the design of new structures. The
Estimation of equivalent viscous damping is an important step in the methodology of the direct displacement based design. Errors in the estimation of this parameter may lead to consequent errors in the ductility demand of the designed elements. Equivalent viscous damping estimated by Jacobsen's approach for steady-state harmonic response are compared with effective damping factors obtained from an iterative procedure using time — history analyses of single-degree-of-freedom systems. In order to separate the effects of elastic-viscous and hysteretic damping the designs and analyses were carried without elastic viscous damping. Six hysteretic models representing a wide range of hysteretic energy absorption characteristics and six artificial records were used in the analysis. It is found that in general Jacobsen's approach overestimates the values for equivalent viscous damping. Based on the analytical results, modified design equations for equivalent viscous damping are proposed.
In this paper, an innovative displacement-based adaptive pushover procedure, whereby a set of laterally applied displacements, rather than forces, is monotonically applied to the structure, is presented. The integrity of the analysis algorithm is verified through an extensive comparative study involving static and dynamic nonlinear analysis of 12 rein-forced concrete buildings subjected to four diverse acceleration records. It is shown that the new approach manages to provide much improved response predictions, throughout the entire deformation range, in comparison to those obtained by force-based methods. In addition, the proposed algorithm proved to be numerically stable, even in the highly inelastic region, whereas the additional modelling and computational effort, with respect to conventional pushover procedures, is negligible. This novel adaptive pushover method is therefore shown to constitute an appealing displacement-based tool for structural assessment, fully in line with the recently introduced deformation- and performance-oriented trends in the field of earthquake engineering.
A new representation of seismic hazard is proposed for Italy based on displacement elastic response spectra in a vibration period range that extends from 0 s to 20 s. This relies on an available seismotectonic zonation and earthquake catalogue, but makes use of a set of very recent, expressly developed attenuation relations. The long period picture of ground motion hazard is illustrated vis-agrave-vis the conventional one based on ground acceleration, and the feasibility of simple approximations of the displacement spectra, useful for design purposes, is shown. We give some foresight on the differences to be expected in hazard maps resulting from the use of a predominantly fault-based seismic source model, as opposed to the more conventional model that includes only spatially extended zones. Finally, we highlight the different hazard exposure of different regions depending on whether we represent hazard with a long or a short period parameter and we discuss the adequacy of recent code provisions regarding elastic displacement spectra.
Using selected sets of high-quality digital strong motion data from different regions (Taiwan, Japan, Italy, and Greece), the salient features of displacement response spectra in the long-period range are illustrated (up to 10 s period) as a function of magnitude, source distance, and site conditions. By means of simple analytical models of displacement waveforms, we have derived analytical expressions for the displacement spectra that provide satisfactory fits to the observations. These expressions also demonstrate that the moment magnitude and distance control the shape of the spectra consistent with the commonly accepted models of the seismic source. Furthermore, we derived from simple physical considerations an analytical expression of the variation of peak ground displacement with magnitude and distance that reasonably fits the observations. The findings of this study are believed to be particularly useful in the formulation of design elastic displacement spectra for seismic codes, and in zoning studies of seismic hazard for long-period structures.
This paper presents a formal probabilistic framework for seismic design and assessment of structures and its application to steel moment-resisting frame buildings. This is the probabilistic basis for the 2000 SAC Federal Emergency Management Agency ~FEMA! steel moment frame guidelines. The framework is based on realizing a performance objective expressed as the probability of exceeding a specified performance level. Performance levels are quantified as expressions relating generic structural variables ''demand'' and ''capacity'' that are described by nonlinear, dynamic displacements of the structure. Common probabilistic analysis tools are used to convolve both the randomness and uncertainty characteristics of ground motion intensity, structural ''demand,'' and structural system ''capacity'' in order to derive an expression for the probability of achieving the specified performance level. Stemming from this probabilistic framework, a safety-checking format of the conventional ''load and resistance factor'' kind is developed with load and resistance terms being replaced by the more generic terms ''demand'' and ''capacity,'' respectively. This framework also allows for a format based on quantitative confidence statements regarding the likelihood of the performance objective being met. This format has been adopted in the SAC/FEMA guidelines.
The modal pushover analysis (MPA) procedure, which includes the contributions of all significant modes of vibration, estimates seismic demands much more accurately than current pushover procedures used in structural engineering practice. Outlined in this paper is a modified MPA (MMPA) procedure wherein the response contributions of higher vibration modes are computed by assuming the building to be linearly elastic, thus reducing the computational effort. After outlining such a modified procedure, its accuracy is evaluated for a variety of frame buildings and ground motion ensembles. Although it is not necessarily more accurate than the MPA procedure, the MMPA procedure is an attractive alternative for practical application because it leads to a larger estimate of seismic demands, improving the accuracy of the MPA results in some cases (relative to nonlinear response history analysis) and increasing their conservatism in others. However, such conservatism is unacceptably large for lightly damped systems, with damping significantly less than 5%. Thus the MMPA procedure is not recommended for such systems.
A global dataset of more than 3,000 ground motion records from 536 sites from Greece, Italy, Turkey, USA and Japan is compiled and used to propose code-oriented elastic acceleration response spectra and soil amplification factors for a new site classification system, which, besides the classical geotechnical parameters and PI, uses also the fundamental period of the site, the thickness of soil deposits and the average shear wave velocity to the seismic bedrock, instead of . We propose a new classification system with the associated amplification factors and normalized response spectra for two seismicity levels, i.e. and . Uncertainties in the estimation of soil amplification factors are captured using a logic-tree approach, which allows the efficient use of alternative models and methods. The aim of this work is to improve the present EC8 soil classification. The effectiveness of the proposed classification system is compared to that of EC8 classification system using an error term, which represents the average dispersion of data within all categories of a given classification scheme. Error terms for the new classification system are lower than the error terms for EC8 classification system at all periods.
Eurocode 8-Part 1 accounts for site effects through the suggestion of appropriate elastic design spectra and amplification factors based on different soil classes. The influence of local site conditions is reflected in Eurocode 8 (EC8) spectra with the shape of the PGA-normalized response spectra and the so-called “soil factor” S, which represents ground motion amplification with respect to outcrop conditions. In the present work we use a global strong-motion database, which was compiled in the framework of SHARE FP7 Collaborative Project of the European Union, to evaluate the present EC8 normalized spectra and associated amplification factors for different soil conditions. Uncertainties in the estimation of improved soil amplification factors are captured using a logic-tree approach, which allows the use of alternative models and methods in an effective way. The influence of PGA range of the strong motion records included in the dataset on spectral shape and soil factors is also examined. The results indicate that for all datasets examined, EC8 normalized elastic acceleration spectra match the empirical data to a satisfactory extent, while estimated soil factors for classes C and D are significantly higher than the ones proposed in Eurocode 8. The proposed design spectra and the new amplification factors are validated with a smaller dataset, which includes records only from stations with well documented soil profiles regarding the dynamic soil properties.
The application of nonlinear static (pushover) procedures for the assessment of existing masonry buildings has been introduced into seismic codes (e.g. EC8, new Italian Seismic Code OPCM 3274/03), but it still includes several critical points in the implementation to real structures. The three-dimensional model of a masonry building can be obtained by assembling frame-type macro-element models of the walls and orthotropic membrane elements in order to represent the mechanical behaviour of flexible floors. This modelling, although very effective in representing the actual behaviour, does not allow to use common simplifications such as rigid floor motion. Moreover, a 3D pushover algorithm requires a predefined pattern of horizontal forces to be applied to the structure and, keeping constant the relative force ratios, the horizontal displacement of a control node is incremented. A new displacement-based algorithm for the adaptive pushover analysis of masonry walls and buildings is presented: the load pattern, in this case, is directly derived, step-by-step, by the actual deformed shape evaluated during the pushover analysis. The proposed procedure seems to be very powerful for in-plane analyses of walls, whilst it requires some corrections in order to be applied to three-dimensional masonry buildings.
Alternative non-linear dynamic analysis procedures, using real ground motion records, can be used to make probability-based seismic assessments. These procedures can be used both to obtain parameter estimates for specific probabilistic assessment criteria such as demand and capacity factored design and also to make direct probabilistic performance assessments using numerical methods. Multiple-stripe analysis is a non-linear dynamic analysis method that can be used for performance-based assessments for a wide range of ground motion intensities and multiple performance objectives from onset of damage through global collapse. Alternatively, the amount of analysis effort needed in the performance assessments can be reduced by performing the structural analyses and estimating the main parameters in the region of ground motion intensity levels of interest. In particular, single-stripe and double-stripe analysis can provide local probabilistic demand assessments using minimal number of structural analyses (around 20 to 40). As a case study, the displacement-based seismic performance of an older reinforced concrete frame structure, which is known to have suffered shear failure in its columns during the 1994 Northridge Earthquake, is evaluated. Copyright © 2008 John Wiley & Sons, Ltd.
Incremental dynamic analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. It involves subjecting a structural model to one (or more) ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level. To establish a common frame of reference, the fundamental concepts are analysed, a unified terminology is proposed, suitable algorithms are presented, and properties of the IDA curve are looked into for both single-degree-of-freedom and multi-degree-of-freedom structures. In addition, summarization techniques for multi-record IDA studies and the association of the IDA study with the conventional static pushover analysis and the yield reduction R-factor are discussed. Finally, in the framework of performance-based earthquake engineering, the assessment of demand and capacity is viewed through the lens of an IDA study. Copyright © 2001 John Wiley & Sons, Ltd.
The European Commission funded the RISK-UE project in 1999 with the aim of providing an advanced approach to earthquake risk scenarios for European towns and regions. In the framework of Risk-UE project, two methods were proposed, originally derived and calibrated by the authors, for the vulnerability assessment of current buildings and for the evaluation of earthquake risk scenarios: a macroseismic model, to be used with macroseismic intensity hazard maps, and a mechanical based model, to be applied when the hazard is provided in terms of peak ground accelerations and spectral values. The vulnerability of the buildings is defined by vulnerability curves, within the macroseismic method, and in terms of capacity curves, within the mechanical method. In this paper, the development of both vulnerability and capacity curves is presented with reference to an assumed typological classification system; moreover, their cross-validation is presented. The parameters of the two methods and the steps for their operative implementation are provided in the paper.
Almost all historical minarets in Turkey were constructed using cut stone, masonry blocks or combination of these two materials.
The structural and geometrical properties of each masonry minaret, or slender tower structure, depend on many factors including
the structural knowledge and applications at the time of construction, experience of the architect or engineer, seismicity
of the region, and availability of construction materials in that area. Recent earthquakes in Turkey have shown that most
masonry minarets in high seismic regions are vulnerable to structural damage and collapse. In this study, in order to investigate
the dynamic behavior of historical unreinforced masonry minarets, three representative minarets with 20, 25, and 30m height
were modeled and analyzed using two ground motions recorded during the 1999Kocaeli and Duzce, Turkey earthquakes. The modal
analyses of the models have shown that the structural periods and the overall structural response are influenced by the minaret
height and spectral characteristics of the input motion. The dynamic displacement and axial stress time histories are computed
at the critical points on the minarets. During recent earthquakes, most minaret failures occurred above the base of the structure.
Consistent with the observed response, the largest stresses were calculated at the same location.
The FP6 EC PROHITECH research project “Earthquake PROtection of HIstorical Buildings by Reversible Mixed TECHnologies” (2004–2009) developed a wide experimental and numerical activity on structures, sub-structures, elements and devices, involving 16 academic institutions of 12 Countries, mostly belonging to the South European and Mediterranean area (AL, B, EG, GR, I, P, RO, SL, TR, ISR, M, MK). The final results were presented at the International PROHITECH Conference held in Rome on 21–24 June 2009. The main objective of this project was to develop sustainable methodologies for the use of reversible mixed technologies in the seismic protection of existing constructions, with particular emphasis to buildings of historical interest. Reversible mixed technologies exploit the peculiarities of innovative materials and special devices, allowing ease of removal if necessary. At the same time, the combined use of different materials and techniques yields an optimisation of the global behaviour under seismic actions. A challenging activity within the project was devoted to large scale models of monumental buildings, which were tested on shaking table for producing damage and then for evaluating the effectiveness of the proposed consolidation systems. In particular, the following monumental models were tested: the Mustafa Pasha Mosque in Skopje, the Gothic Cathedral in Fossanova, the St. Nikola Byzantine Church in Psacha and the Parthenon temple in Athens. Beside the experimental activity, appropriate numerical models were developed in order to both predict and interpret the testing results.
This chapter proposes a method for the vulnerability assessment of ordinary masonry buildings at territorial scale, to be used in the framework of a probabilistic seismic risk analysis. The classification of the built environment is based on the SYNER-G taxonomy and is dependent on the available data in the study area; it consists in the aggregation of buildings characterized by a homogeneous seismic behavior, which is known from empirical damage on similar structures, proper analytical models or expert judgment. The general definition of fragility functions is recalled, through the use of static non linear analysis for the evaluation of the capacity spectrum and the calculation of the maximum displacement by the demand spectrum. The selection of proper intensity measures for masonry buildings is treated, as well as the definition of damage and performance limit states. A detailed procedure for the propagation of uncertainties is proposed, which is able to single out each independent contribution. Then, some recommendations for deriving fragility functions with different approaches are given. In particular, it is shown how the macroseismic vulnerability method, derived from EMS98, can be used by expert elicitation or if empirical data are available. Moreover, the DBV-masonry (Displacement Based Vulnerability) method is proposed as a powerful tool for the derivation of fragility function by an analytical approach. Finally, fragility functions are derived for ten different classes of masonry buildings, defined by a list of tags from the taxonomy, in order to show the capabilities of the proposed methods and their cross-validation.
An approach for the evaluation of the vulnerability of classes of buildings is presented. The method is derived from concepts developec for the detailed analysis of existing buildings, based on an estimation of their displacement and energy dissipation capacity. The limited data normally available for loss assessment at a regional scale correspond to an equivalent uncertainty of the results, but an analytical evaluation of the response of the building, including its energy dissipation and deformation capacity, is still attempted. The results are presented in terms of probability of occurrence of each specific damage limit state for a given earthquake motion, represented through an appropriate displacement response spectrum for each building. However, the results may be considered meaningful only for a global loss estimate prediction, and should not be used to assess the response of single buildings.
Shortly after the October 31, 2002, Molise, Italy, earthquake, a widespread fitness-for-service and building damage assessment was launched. In two months, more than 23,000 buildings were inspected using a standardized damage assessment form. As many as 100 inspection teams, consisting of public servants and volunteer professionals, totaled approximately 80,000 person-hours. Analysis of the collected building type and damage data shows high-vulnerability masonry buildings with significant preexisting damage. With the sole exception of San Giuliano, the modal values of the observed damage occurred for the negligible-to-slight damage levels D=0 or D=1, with only a few buildings showing higher damage levels. Nevertheless, due to their high vulnerability, about 40% of the inspected buildings were unusable, with important consequences for the number of people needing shelter. The survey made it possible to determine the usability of about 12,000 buildings and the repairs needed for about 1,000 buildings. [DOI: 10.1193/1.1769373]
The medieval fortresses are a very common and distinctive type among the Emilian historical constructions and the earthquake of May 20 and 29, 2012 highlighted their high vulnerability. Starting from the analysis of the geometrical and constructive features, the interpretation of their seismic vulnerability has been based on an accurate damage assessment and supported by the numerical results of typical configurations. An abacus of recurring seismic damage mechanisms in fortresses has been proposed: it in particular concerns the towers and their interaction with the fortress perimeter walls. Moreover, the seismic response of the most important fortresses in the epicentral area has been described referring to their historical notes, the recent interventions and their influence on the seismic damage.
The seismic Performance-Based Assessment (PBA) of monumental buildings requires to consider safety and conservation objectives, including also the possible presence of artistic assets. In order to face these issues, the case study of the Great Mosque of Algiers is analysed in this paper: in fact, besides to be one of the remaining Almoradiv architecture and the oldest mosque of the city, it is also characterized by the presence of a mihrâb, a decorated arched niche that represents an interesting artistic asset to be included in the PBA. Within this context, particular attention has been paid to the choice of the most reliable modelling strategy for the application of the displacement approach in the PBA procedure, as a function of different possible seismic behaviours. In the case of Great Mosque both the current state of the building and a virtual strengthened condition are analysed. It is worth noting that, while in the current state the seismic behaviour of the asset is well described by a set of macroelements that may be analysed independently (through 2D models), in the second case the strengthening intervention leads to the adoption of a 3D global model (indeed, the roof bracing promotes a “box-type” behaviour). In the paper, the integrate use of three different modelling strategies of different complexity is discussed: the finite element model, the equivalent frame approach and the macro-block model. The results of nonlinear analyses performed (static and kinematic) constitute the main tool to interpret the seismic response of the asset, perform the PBA and address the choice on the rehabilitation decisions. These latter in this case are mainly affected by the occurrence of too high deformations in local portions of the building, including that in which the artistic asset is located.
The seismic assessment of rocking masonry structures is a complex task, due to the high sensitivity of the behavior to the characteristics of the input motion. The paper compares the results offered by different models and the reliability of widely used intensity measures. A displacement-based approach based on an incremental limit analysis of rigid blocks is proposed for the performance-based assessment of rocking masonry structures, such as: rocky structures (archeological remains, obelisks, columns, trilithons), arch-piers systems (e.g. triumphal arches, belfries), out-of-plane mechanisms of walls (standing out walls, façades in buildings or churches etc.) or artistic assets prone to overturn (pinnacles, statues etc.). The method is compatible with the format of the PERPETUATE performance-based assessment method for cultural heritage assets