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Assessment of churches based on empirical data at a territorial scale is a suitable tool to have an overview of the seismic behaviour of this peculiar structural typology and to evaluate their current state of vulnerability. Fragility and vulnerability curves are also aimed to perform the analysis of different seismic scenarios. The paper presents a detailed typological analysis of 633 single-nave churches, as a selected subset of the database previously examined by the authors, with the aim of evaluating more in detail the influence of some parameters, such as masonry typology, church dimensions and presence of the bell tower, on the vulnerability of the overall church. Then, specific analyses are carried out to assess the influence played by single mechanisms on the definition of the overall damage index, with the focus of providing qualitative evaluations and explicit vulnerability and fragility curves related to the most recurring and significant collapse mechanisms. This is an original contribution of the paper in the field of the vulnerability assessment of churches, since nowadays little information is available in the literature about the damage levels related to specific mechanisms, while most attention is still focused on global damage. [ABSTRACT FROM AUTHOR]

This paper addresses how residents can safely access shelters from their buildings. Firstly, we investigated Xiaying Village, a typical community with severe buildings damage at the epicentre of the Ms5.0 magnitude earthquake in Tonghai that occurred on August 13, 2018, and found that the injured residents when escaping resulted from the damage to masonry buildings. Secondly, a probabilistic approach combining response spectrum and allowable maximum acceleration is proposed to estimate the damage risk of masonry buildings with inadequate seismic performance in old communities. Thirdly, three models are proposed to assess the risk of the escape path, which include all scenarios of the escape of residents to shelters. Finally, an accessibility analysis of the paths that residents may choose to escape to the shelter is presented. The results of the community escape case study in the Tonghai earthquake show that the probabilistic approach to estimating the escape risk is feasible, and the number of damaged buildings in the escape path dictates the accessibility of residents to the shelter. The proposed method is important for guiding old community residents to escape when a strong earthquake strikes, and it is an effective way to improve community disaster resilience. [ABSTRACT FROM AUTHOR]

Seismic risk estimation for urban building clusters is essential when developing regional seismic resilience models. A masonry structure is a type of building with a large stock, broad applicability, and simplified construction technology. The traditional seismic intensity measures and fuzzy quantification of structural vulnerability levels result in low accuracy in estimating and predicting seismic damage to masonry structure clusters. This paper proposes a method for evaluating bivariate seismic intensity measure. Nonlinear dynamic and spectral analyses were conducted on real acceleration records monitored by ten stations during the Wenchuan earthquake in Sichuan, China, on May 12, 2008. The outdated seismic vulnerability level of masonry structures is updated, and an optimized structural seismic risk model based on the seismic damage database of 2407 masonry structures in Dujiangyan city under the influence of the Wenchuan earthquake is established. An innovative seismic risk membership index algorithm was developed, and a vulnerability curve was generated for masonry structures considering multiple risk membership indices. An improved seismic risk index calculation function is proposed using the proposed updated vulnerability level, and the seismic risk index curve and stripe model of typical urban masonry building clusters are established. According to the field investigation of the actual structures in Dujiangyan city affected by the Wenchuan earthquake, the typical failure features and disaster mechanism of masonry structures are reported and analysed, and measures and methods to improve and enhance the seismic capacity of such buildings are proposed. The developed seismic risk model for urban masonry structures can contribute positively to the development of relatively accurate seismic resilience models for urban buildings and can improve the accuracy of seismic risk estimation for masonry structures. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of soil–structure interaction and site amplification on the seismic response of one of the towers of the Theodosian walls of Constantinople during the Kocaeli earthquake in 1999, that largely damaged it. The interacting system is first analysed in the frequency domain by the well-known replacement oscillator model, turning out that the effect of soil–structure interaction could be relevant. The complete system is then examined by the direct approach considering non linearity of the behaviour of both the structure and the soil. The failure mechanism detected from where stress and plasticization concentrate into the masonry panels is consistent with the out-of-plane mechanism of one of the tower façades triggered by the reference earthquake. The focus was then set on the effectiveness of some retrofitting interventions, including the lateral disconnection of the embedded sides of the tower from the surrounding soil, the soil treatment by grouted columns and the classical technique for masonry rehabilitation. Even though the latter choice is the most common one, retrofitting interventions concentrated into the soil could be effective as well. Their use should be properly considered when the scope of the intervention is the preservation of cultural heritage. [ABSTRACT FROM AUTHOR]

Barcelona is in an area of low- to medium-seismicity and its earthquake vulnerability and risk has been assessed in different studies over the last 20 years. Most of these works have developed vulnerability models for the representative building classes of the city, trying to capture their main characteristics, and have been mostly represented through fragility curves. However, due to the lack of data for historical earthquake losses in the city, it has not been possible to validate, nor calibrate, any of these vulnerability models. In the absence of earthquake loss data, the objective of this paper is to compare the earthquake risk results of Barcelona, using common hazard and exposure datasets and different sets of vulnerability functions from previous studies to see how they rank compared with other locations with similar studies but more complete historical loss data. The results show large differences between the analysed vulnerability datasets, with some results that in our view tend to overestimate earthquake risk in Barcelona, and also allow identifying critical aspects that require future research. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to present the damage features of masonry structures and engineering seismology studies after the 19–22 November 2021 Köprüköy earthquakes (Mw 5.1 and Mw 4.7). The masonry structures damaged near the epicenter have been examined. Damages have been detected that such as vertical cracks in the walls of the masonry structures, out-of-plane bending of the walls, splits in the joints of the walls, and separation of the floors from the elements such as walls and roofs. The fact that the structures in the region do not receive an engineering service and that they are constructed without complying with the relevant earthquake regulations are thought to cause such damage. The damage in Topçu village of Köprüköy district in Erzurum is more than in other settlements. Microtremor measurements have been applied in Topçu Village to investigate dynamic soil features. The soil amplification factor and soil predominant period have been obtained ~ 6.8 and ~ 1.3 s for the first measurement and ~ 9.4 and ~ 1.3 s for second location, respectively. Also, Vs30, bedrock depth, vulnerability index, and shear strain parameters have been calculated using some empirical relations. High bedrock depth and low Vs30 values are obtained for both measurements. The vulnerability index and shear strain values also indicate that the vulnerability of the soil is high. In order to remain in the safe zone for structures in a possible future earthquake, it has been suggested that it should comply with the earthquake-soil-structure relationship and should be designed in accordance with the earthquake regulation standard. [ABSTRACT FROM AUTHOR]

Recent Italian earthquakes have shown the seismic vulnerability of many typical historical masonry churches characterized by one nave and wooden roofs. Under transverse earthquake, the nave transverse response of this kind of churches can be influenced by the geometrical and material features. To increase the seismic performance, strengthening interventions aimed to pursue the global box-behavior by the realization of dissipative roof-structure represent a valid strategy, especially to avoid out-of-plane mechanisms. In this way, the roof structure must be able to represent a tool for the damped rocking of the perimeter walls. Cross-laminated timber (CLT) panels with calibrated metal connections have been recently adopted in experimental tests as a valid solution to obtain a roof-diaphragm with ductile behavior, satisfying the conservative restoration criteria at the same time. In this paper, after a description of the numerical approach for the damped rocking mechanism for one nave configuration church, the effectiveness of different CLT based roof-diaphragms in the nave transverse response is investigated for four historical churches. The seismic responses are performed by comparative dynamic nonlinear analyses and the results are shown in terms of displacements and shear actions transferred to the façade. The influence of the geometrical features of the churches on the nave transversal response is deepened by sensitivity analyses with the aim to predict the displacements and shear variations under the same earthquake excitation. [ABSTRACT FROM AUTHOR]

Two strong earthquakes hit Thessaly region on March 3rd, 2021 (Mw = 6.3) and on March 4th, 2021 (Mw = 6.1). The epicentres of the earthquakes were located at approximately 23 and 29 km respectively NW of Larissa, one of the most populous cities in Greece. Several aftershocks followed thereafter. Although no injuries were recorded, several structures suffered significant damage close to the epicentre, while some others collapsed. Approximately 300 residents of the village of Damasi were transferred to temporary settlements and tents. The event occurred during the COVID19 lockdown and created significant stress and disruption to residents. This paper focuses on the earthquake swarm itself as well as the damages observed in residential buildings, schools, and churches in the earthquake-stricken region. The earthquakes mainly impacted low-rise domestic masonry buildings, while the more modern reinforced concrete structures built following the recent seismic regulations were almost unaffected. The typology of buildings in the region, together with photographs demonstrating the extent of damage are presented herein. Despite the rather satisfactory performance of modern buildings in recent earthquakes in Greece, the preliminary investigations from the Thessaly Earthquakes showed that there is still a significant level of vulnerability in existing masonry building stock constructed using traditional methods and materials. This issue could re-emerge in future earthquakes striking other rural areas of Greece, something that needs to be addressed systematically in the future. [ABSTRACT FROM AUTHOR]

In this paper, the seismic resistance of unreinforced masonry (URM) cylindrical columns is investigated with an equivalent static analysis procedure. To this end, an existing numerical model developed for the stability analysis of masonry elements with rectangular cross-section is utilized and modified for the cylindrical columns. In the numerical model which takes into account the cracking of the sections and the second-order effects, the columns are divided ideally into sufficiently high number of elements, each having uniform curvature. The columns are modeled as prismatic cantilevers undergoing their own weights, eccentric vertical loads and distributed and concentrated static horizontal loads equivalent to the inertia actions. By considering two examples of columns, firstly a reference column and secondly a column from a real building, lateral seismic coefficient versus top drift level curves are obtained. On the basis of these curves, lateral load behavior of the columns is interpreted and maximum seismic load values which can be resisted by each column are determined. Implementing parametric analyses on the reference column, sensitivity of the seismic resistance to parameters such as column slenderness, magnitude and eccentricity of vertical top load, and the flexibility parameter is determined. The influence of some structural imperfections such as the deviation from vertical on the seismic resistance is also discussed in the paper. [ABSTRACT FROM AUTHOR]

Confined masonry buildings are common structural systems in many seismic-prone regions of the world. According to the building code provisions, an appropriate continuous tie system should be provided in these buildings to bind the structural elements together and stop separation and disintegration of these elements under ground shaking. Since usually prescriptive design provisions with minimum calculations are used for constructing confined masonry buildings, investigating their performance in real seismic events is of great importance. In this paper observations made on the performance of confined masonry buildings during the destructive Sarpole Zahab, Iran, earthquake of November 12, 2017 are reported. The earthquake had caused different types of damage in both the structural and non-structural elements of the buildings. Damages were found to be primarily due to large structural irregularities and poor workmanship. Nonetheless, it was noted that those buildings with no significant irregularities, in the construction of which all the code's main provisions had been followed, survived the earthquake and did not experience partial or total collapse. It is suggested that in the taller, two or three storey buildings, with the aim of enhancing the lateral deformation capacity of the load bearing walls, some modifications on the dimensions and reinforcement detailing of the vertical tie elements, particularly those located at the corners of the buildings, to be carried out. In addition, as it has been repeatedly observed in the past earthquakes that after the partial or total collapse of the load bearing walls the tie-beams and tie-columns have served as a secondary gravity load-resisting system and prevented collapse of floor and roof slabs, it is suggested that the adequacy of the current prescriptive detailing of the tie system in acting as a temporary secondary load-bearing system to be verified. [ABSTRACT FROM AUTHOR]

On December 29, 2020, nine months after the March Mw 5.4 Zagreb earthquake and amidst the COVID-19 lockdown, a devastating Mw 6.4 earthquake struck near the town of Petrinja, about 50 km SE from the country's capital Zagreb. It was preceded by the Mw 4.9 foreshock from the day before. The main shock claimed 7 fatalities and caused widespread damage. Historical centers of nearby cities with invaluable heritage buildings were significantly affected as were the many residential buildings, built mainly of unreinforced masonry. Damage was observed as far as 60 km from the epicenter. This paper summarizes the seismological aspects of the Mw 6.4 Petrinja earthquake, the emergency response and the main impacts to people and buildings. The description and findings are based on the field observations and a series of post-earthquake activities led by the team of the Faculty of Civil Engineering, University of Zagreb. Typical damage to buildings and usability data are presented with examples based on 50,000 inspection results. By far the most affected were the unreinforced masonry buildings, followed by confined masonry, whereas reinforced concrete buildings were the least affected. The total direct and indirect losses are estimated to 4.8 billion EUR. The provided information represents a useful basis and impetus for improving emergency action and long-term disaster reduction plans in other regions with similar building exposure and seismotectonic settings. [ABSTRACT FROM AUTHOR]

This paper presents the fragility assessment of non-seismically designed steel moment frames with masonry infills. The assessment considered the effects of multiple earthquakes on the damage accumulation of steel frames, which is an essential part of modern performance-based earthquake engineering. Effects of aftershocks are particularly important when examining damaged buildings and making post-quake decisions, such as tagging and retrofit strategy. The procedure proposed in the present work includes two phase assessment, which is based on incremental dynamic analyses of two refined numerical models of the case-study steel frame, i.e. with and without masonry infills, and utilises mainshock-aftershock sequences of natural earthquake records. The first phase focuses on the undamaged structure subjected to single and multiple earthquakes; the effects of masonry infills on the seismic vulnerability of the steel frame were also considered. In the second phase, aftershock fragility curves were derived to investigate the seismic vulnerability of infilled steel frames with post-mainshock damage caused by mainshocks. Comparative analyses were conducted among the mainshock-damaged structures considering three post-mainshock damage levels, including no damage. The impact of aftershocks was then discussed for each mainshock-damage level in terms of the breakpoint that marks the onset of exceeding post-mainshock damage level, as well as the probability of exceeding of superior damage level due to more significant aftershocks. The evaluation of the efficiency of commonly used intensity measures of aftershocks was also carried out as part of the second phase of assessment. [ABSTRACT FROM AUTHOR]

Despite significant research advances on the seismic response analysis, there is still an urgent need for validation of numerical simulation methods for prediction of earthquake response and damage. In this respect, seismic monitoring networks and proper modelling can further support validation studies, allowing more realistic simulations of what earthquakes can produce. This paper discusses the seismic response of the "Pietro Capuzi" school in Visso, a village located in the Marche region (Italy) that was severely damaged by the 2016–2017 Central Italy earthquake sequence. The school was a two-story masonry structure founded on simple enlargements of its load-bearing walls, partially embedded in the alluvial loose soils of the Nera river. The structure was monitored as a strategic building by the Italian Seismic Observatory of Structures (OSS), which provided acceleration records under both ambient noise and the three mainshocks of the seismic sequence. The evolution of the damage pattern following each one of the three mainshocks was provided by on-site survey integrated by OSS data. Data on the dynamic soil properties was available from the seismic microzonation study of the Visso village and proved useful in the development of a reliable geotechnical model of the subsoil. The equivalent frame (EF) approach was adopted to simulate the nonlinear response of the school building through both fixed-base and compliant-base models, to assess the likely influence of soil–structure interaction on the building performance. The ambient noise records allowed for an accurate calibration of the soil–structure model. The seismic response of the masonry building to the whole sequence of the three mainshocks was then simulated by nonlinear time history analyses by using the horizontal accelerations recorded at the underground floor as input motions. Numerical results are validated against the evidence on structural response in terms of both incremental damage and global shear force–displacement relationships. The comparisons are satisfactory, corroborating the reliability of the compliant-base approach as applied to the EF model and its computational efficiency to simulate the soil–foundation–structure interaction in the case of masonry buildings. [ABSTRACT FROM AUTHOR]

Many historical masonry towers belong to architectural heritage. Their preservation is still a critical issue in several countries. In fact, the experience of past earthquakes has shown that even earthquakes of moderate intensity can cause the collapse of these historical structures due to their slenderness together with irregularities, openings, leaning phenomena and adjacent lower buildings. The damage and changes suffered over the centuries, and the complex behaviour of the materials makes the performance of this type of structures more uncertain, and the seismic analysis and the remedial measures to achieve their protection a very complex task. This paper presents a complete study (from the on-site diagnostic investigations to the seismic assessment and non-invasive strengthening) of an ancient masonry tower in Torre Orsaia (Southern Italy). The paper, through the discussion of the case study, shows effective procedures to assess the seismic safety of masonry towers and plan interventions without too time- and cost-consuming processes. The results have established that the deep and wide cracks on the belfry are due to the loss of tension of the ancient tie-rods. The seismic safety of the tower has been carried out using three levels of analysis: LV1 (evaluation with simplified models), LV2 (analysis of local collapse mechanisms) and LV3 (global analysis). The analyses have shown that the critical mechanism is the simple overturning of the masonry piers of the belfry due to the ineffective tie-rods. The corresponding safety index in terms of peak ground acceleration is 0.305. To avoid this undesired mechanism and, at the same time, fully close the cracks, a strengthening intervention based on stainless steel reinforcing rings has been developed. This chaining system avoids the local mechanisms of the piers of the belfry and allows developing global mechanisms. After retrofit intervention, the seismic analysis has shown that the safety index increases to 0.716 for the LV2 analysis and 0.793 for the LV3 analysis. [ABSTRACT FROM AUTHOR]

An earthquake of MW = 6.5 occurred on May 24, 2014, at 12:25 h local time (09:25 GMT), its epicenter in the Aegean Sea, 25 km north of Gökçeada. The effect of the earthquake produced the most damage in the rural houses of Gökçeada. This paper describes the evaluations made through onsite field observations of the damages inflicted on the structures of thirty rural houses in the Tepeköy settlement connected to Gökçeada. An evaluation was made of the types of damage, the mechanisms of damage and the causes of the damage sustained by these houses, which all had similar structural characteristics but different plan typologies and suffered varying levels of damage. The damage observed in Gökçeada was classified using the catalogue of mechanisms originally developed for the failure mechanisms identification and vulnerability evaluation procedure. The general types of damage were cracks in the loadbearing external walls and corners, diagonal cracks starting from the corners of doors and windows, vertical out-of-plane displacement of external walls, out-of-plane fragmentation or disintegration and collapse of external wall and partial collapse of loadbearing internal walls, ruptures in the outer surfaces of loadbearing external walls, partial collapse of roof structure, partial collapse of hearth and chimney sections, rupture or flaking of window and door lintels. The causes of the general damage may be cited as an irregular bonding system, weak mortar, stone block formation, stone block size, absence of tie beams, corners weakly connected, weak connection of wall-roof system, week connection of wall-floor system, and different internal wall systems. The levels of damage and the mechanisms of damage vary depending upon the number of causes of the damage, the particulars of the layout, and some structural properties. In terms of the characteristics of the layout, an increase in unsupported loadbearing wall lengths led to more destructive damage mechanisms in the houses. In terms of structural characteristics, the construction of the internal wall system with timber on the upper floors, and with stone material on the lower floors was a major factor in increasing the level of damage and determining its type and mechanism. [ABSTRACT FROM AUTHOR]

This paper focuses on the structural performance of existing masonry and reinforced concrete bridges which were surveyed in the aftermath of the 2016 Central Italy earthquakes. Typical bridge vulnerabilities are first reviewed, as they provide a reference for the response of the bridges that were damaged by the 2016 earthquake swarm. Case studies are then discussed and preliminary numerical analyses are carried out to interpret the observed failure modes. In general, all surveyed masonry bridges experienced some extent of damage, particularly when built with poor-quality materials and subjected to geotechnical-induced effects. However, they offered a robust response in terms of collapse prevention. The majority of existing reinforced concrete bridges, although designed primarily for gravity loads, exhibited acceptable performance; however, local damage due to the poor maintenance of the structural systems was observed, which affected primarily the non-structural components of the bridges. [ABSTRACT FROM AUTHOR]

Seismic events that struck Italy in the last years had a dramatic impact on historical and cultural heritage. Damage occurred on existing masonry buildings, in particular on churches, stressed out the need to better understand the seismic behaviour of this type of constructions as well as to define more appropriate mitigation strategies to be applied at large scale. This study deals with a predictive methodology for vulnerability assessment of churches in large territorial areas. Focusing the attention on three naves churches of Abruzzi, the paper proposes modifications and integrations of an existing methodology taken by literature. These modifications are defined through a calibration procedure based on damage observation of 64 three naves churches located at different distances from the epicentre of the 2009 earthquake. The proposed model is employed to predict damage level distribution for different earthquake intensities, allowing fragility curves to be plotted and therefore potential damage scenarios to be represented. [ABSTRACT FROM AUTHOR]

The paper presents the vulnerability assessment of the Hassan Bey's Mansion, located in the Medieval City of Rhodes in Greece. To this aim, the procedure developed in PERPETUATE project for the seismic assessment at scale of a single monument is adopted: it follows the performance-based concept making use of nonlinear static analyses. The main outcome of the assessment is presented in the paper in terms of maximum seismic intensity measure (the one selected as the most representative for the examined asset) compatible to various performance levels: it is used to address also the rehabilitation decisions. Within this context, the attention of this paper is focused on the use of sensitivity analysis for the identification of the main parameters that affect the structural response. Uncertainties considered in this application are both aleatory and epistemic. The epistemic uncertainties concern the effectiveness of the infilled openings: in fact, this feature strongly characterizes this building that has been subjected to many transformations along its life. Moreover, seven random variables have been considered to account for the aleatory uncertainties: they involve the material properties, the material constitutive law as well as floor rigidity. A total of 60 nonlinear static analyses have been performed for the sensitivity analysis, which represents a powerful tool for setting-up a possible investigation plan and addresses the final assessment. The resulting safety factor, computed in terms of return period, varies from 0.20 to 0.27, highlighting that the structure is not able to satisfy the target performance levels. Possible rehabilitation measures are proposed afterwards, in particular by quantitatively assessing the effect associated to the stiffening of diaphragms (very flexible in the original state). [ABSTRACT FROM AUTHOR]

In the paper, possibilities of correlation of structural damage and damage of attached artistic assets on multi-leaf stone masonry walls by means of destructive and non-destructive testing (NDT) methods are investigated. Results from two testing campaigns carried out at the University of Genoa and University of Ljubljana are briefly presented. In particular, diagonal tests with different levels of pre-compression and shear tests under different boundary conditions were carried out in Genoa and Ljubljana, respectively. During the tests, different damage limit states (DL) of both masonry walls (SE) and attached plasters (AA) were investigated by means of NDT's. Two different types of rubble stone masonry were considered (uncoursed random rubble vs. coursed squared rubble). For AA the results are presented in relative form in dependence from the DL of SE. Obtained results are influenced both by the type of test and tested masonry. Results of NDT revealed strong potential and a need for data fusing of both investigated methods for the evaluation of the state of the degradation behind the plaster. [ABSTRACT FROM AUTHOR]

The paper presents the application of the seismic assessment procedure developed in the PERPETUATE project on a single monument, the Neoclassical School in the Medieval City of Rhodes. The PERPETUATE methodology for the estimation of seismic risk of cultural heritage assets is based on the principles of performance-based assessment ( PBA), using nonlinear static procedures. The outcome of the PBA methodology is the maximum seismic intensity measure compatible to different performance levels. The focus of the paper is on the application of the methodology, considering the effects of both soil-foundation-structure interaction ( SFSI) and masonry foundation flexibility on the building response, before and after rehabilitation design measures. It is found that SFSI and foundation flexibility produce larger displacements and reduce the maximum ground acceleration that the building can sustain by over 50 %. However, despite the detrimental effects of SFSI on the acceleration capacity, SFSI and foundation flexibility may have a favorable effect on the structure safety, as they modify the collapse mechanism. The results of seismic analyses showed that the building, in its current state, does not sustain the demands for the Life Safety and Collapse Prevention performance levels. Stiffening the roof of the structure and providing sufficient anchorage to the structure, along with systematic grouting of the masonry walls, are the principal rehabilitation decisions considered herein. Mitigation measures were evaluated, considering SFSI and the analyses revealed the adequacy of the proposed retrofitting measure, which combines vertical (wall) and horizontal (roof) stiffening. [ABSTRACT FROM AUTHOR]

The earthquake sequence started on May $$20$$ th 2012 in Emilia (Italy) affected a region where masonry constructions represent a large part of the existing building stock and the construction of new modern masonry buildings is a common practice. The paper is focused on the performance of common architectural configurations, typical for residential or business use. The large majority of old masonry buildings is made of fired clay bricks. The seismic performance of these buildings is particularly interesting since major past earthquakes in Italy affected areas with mainly stone masonry structures. Apart from examples showing systematic or peculiar structural deficiencies governing the vulnerability of several buildings, the overall seismic performance of these structures to repeated shaking, with PGA as large as 0.25-0.3 g was rather good, despite the major part of them were only conceived for carrying vertical loads. In fact, seismic design is mandatory in the area only since 2003. Modern low-rise masonry buildings erected after this date and incorporating seismic design and proper detailing resulted in most cases practically undamaged. The examples reported in the paper allow an evaluation of the superior performance of seismically designed modern masonry buildings in comparison to older ones. [ABSTRACT FROM AUTHOR]

The collapse of stone masonry is one of the greatest causes of death in major earthquake events around the world. This paper investigates a recently developed retrofitting technology specifically aimed at preventing or prolonging the collapse of stone masonry buildings under strong earthquakes. This technology uses common polypropylene packaging straps to form a mesh, which is then used to prevent or prolong collapse. This paper examines the findings from static and dynamic testing of the proposed retrofit. It is shown that the proposed technique effectively prevents brittle masonry collapse and the loss of debris. [ABSTRACT FROM AUTHOR]

Traditional non-reinforced masonry walls are particularly prone to failure when subjected to out-of-plane loads and displacements caused by earthquakes. Moreover, singularities such as openings in façades may trigger local collapse, for either in-plane or out-of plane motion. Bearing in mind all the former limitations, STAP, with the scientific support of ICIST and LNEC, has been developing a reduced intrusiveness seismic strengthening methodology for traditional masonry structures. The technique consists in externally applying Glass Fibre Reinforced Polymer (GFRP) composite strips to one or both faces of walls. Connection between GFRP composite strips and masonry substrate is enhanced through specifically detailed anchorages or confinement connectors. This technique has been developed and studied through an extensive series of experimental tests, which are briefly reviewed. This paper focuses more deeply on the latest experimental program, aimed at the characterization of the masonry-GFRP composite interface behaviour. This testing program comprised 29 masonry specimens, strengthened with externally bonded GFRP composite strips with anchorages. The testing variables were the number and spacing of anchorages as well as the loading history type: monotonic or repeated. Results clearly show that the use of anchorages dramatically enhances bond behaviour and that its number and spacing have a significant effect on deformation capacity and a less pronounced effect on strength. Based on experimental evidence, this paper also provides a calculation model and ULS safety assessment procedure for out-of-plane strength of reinforced masonry walls. This calculation model leads to interaction curves on strengthened masonry walls subjected to compression and out-of-plane flexure. [ABSTRACT FROM AUTHOR]

The paper presents the results of a broad experimental investigation conducted through diagonal compression tests on masonry specimens strengthened with a mortar coating applied on both surfaces of the wall and reinforced with a glass fiber reinforced polymer (GFRP) mesh. Four types of masonry, three different types of masonry mortar and five diverse GFRP meshes for the reinforcement were considered. In particular, solid brick masonry 250 and 380 mm thick, two-leaf brick masonry with rubble conglomerate infill and rubble stone masonry were tested. The diagonal compression tests, performed on 60 square masonry specimens with loading-unloading cycles up to the collapse, evidenced a good effectiveness of the strengthening technique in terms of both resistance and ductility. Results also showed the resistance increment in reinforced samples is generally greater for weaker masonry types and, referring to a single masonry type, for specimens built with a weaker mortar. Furthermore, the different GFRP meshes influenced very little the resistance of specimens, but higher reinforcement contents induced a lower decrease of the diagonal load after the cracking. [ABSTRACT FROM AUTHOR]

This paper presents the record of damages which were observed in Pakistan due to a strong earthquake on 16 April 2013 in Iran. Mashkel was the nearest town in Pakistan close to the epicentre of earthquake. The damages were documented by a survey team during the visit of Mashkel. The intensity of earthquake in most of the visited areas was found to be VIII on the Modified Mercalli Intensity scale. The infrastructure facilities were undamaged and were operating satisfactorily. On the other hand, heavy damage to adobe buildings was caused by the earthquake. Most of the building failure was resulted by the out-of-plane wall collapse; nearly 40 % adobe buildings were collapsed due to ground shaking in some of the affected areas. Reinforced concrete and cement concrete block masonry buildings performed better than adobe buildings. Using the data of building damage and earthquake intensity fragility curves for adobe buildings in Mashkel were developed. [ABSTRACT FROM AUTHOR]

The response of historic masonry buildings to tectonic ground displacements is studied through analysis of a simple yet representative soil-foundation-masonry wall system. A nonlinear 3D finite element method is developed and employed to reproduce the strong nonlinear response of the rupturing soil, as well as the masonry structure. Following a sensitivity analysis of the effect of the exact location of the structure with respect to the emerging fault, the paper discusses several characteristic mechanisms of soil-structure interaction and evaluates the associated structural distress. The observed failure pattern and the consequent structural damage are shown to depend strongly, varying from minimal to dramatic, on the exact position of the structure relative to the fault. Alleviation of tectonic risk through foundation enhancement/improvement is investigated by considering alternative foundation systems. Results highlight the advantageous performance of rigid embedded and continuous foundations as opposed to more flexible and isolated supports indicating that foundation strengthening may provide important shielding against settlement and structural drift. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

On Wednesday 11th May 2011 at 6:47 pm (local time) a magnitude 5.1 Mw earthquake occurred 6 km northeast of Lorca with a depth of around 5 km. As a consequence of the shallow depth and the small epicentral distance, important damage was produced in several masonry constructions and even led to the collapse of one of them. Pieces of the facades of several buildings fell down onto the sidewalk, being one of the reasons for the killing of a total of 9 people. The objective of this paper is to describe and analyze the failure patterns observed in reinforced concrete frame buildings with masonry infill walls ranging from 3 to 8 floors in height. Structural as well as non-structural masonry walls suffered important damage that led to redistributions of forces causing in some cases the failure of columns. The importance of the interaction between the structural frames and the infill panels is analyzed by means of non-linear Finite Element Models. The resulting load levels are compared with the member capacities and the changes of the mechanical properties during the seismic event are described and discussed. In the light of the results obtained the observed failure patterns are explained. Some comments are stated concerning the adequacy of the numerical models that are usually used during the design phase for the seismic analysis. [ABSTRACT FROM AUTHOR]

This paper is focused on the illustration of on site works developed on some historical centres struck by L'Aquila earthquake of April 6, 2009 starting from the first emergency phase. The large number of minor historical centres damaged and the highly differentiated level of damage occurred implied the need of different procedures to study them. The common goal of all these studies is to illustrate the variability of the seismic response of historical masonry buildings trying to identify both the causes that have increased the damage (vulnerabilities) and the factors that have limited or prevented it (strengths). The preliminary results allow to formulate a first evaluation in view of drawing up reconstruction plans. [ABSTRACT FROM AUTHOR]

This paper focuses on the earthquake performance of St. Konstantinos church that was damaged during 1995 Kozani earthquake. The structural elements that suffered the most damage were the main longitudinal exterior masonry walls, which included a considerable number of door and window openings. Initially, a numerical study is performed to determine the stiffness properties of representative simple masonry wall arrangements that included combination of openings. Based on the findings of this preliminary study, a three-dimensional (3-D) numerical simulation of the St. Konstantinos church was built. An analysis of the seismic response was next performed where the masonry walls were represented by linear "beam type" frame elements. The recordings of the ground acceleration that were obtained during the earthquake at a close distance from the church were utilized. The deformation levels obtained from this 3-D seismic analysis are used next, to approximate the earthquake performance of masonry walls through a more refined two-dimensional (2-D) FEM representation. These linear simulation results are utilized to predict the development of flexural or shear limit-state conditions for the exterior masonry walls. It was verified that the observed damages are in agreement with such predictions. The 2-D numerical investigation was extended to include a non-linear simulation of the observed behaviour utilizing either a Mohr-Coulomb or a modified von Mises failure envelope. Again, the observed damage of the masonry wall was approximated reasonably well by these non-linear numerical predictions. A retrofitting scheme which included the construction of internal reinforced concrete jacketing was also briefly presented and its beneficial result in the structural performance was verified. [ABSTRACT FROM AUTHOR]

The 2009 L'Aquila, Italy earthquake highlighted the seismic vulnerability of historic masonry building structures due to improper 'strengthening' retrofit work that has been done in the last 50 years. Italian seismic standards recommend the use of traditional reinforcement techniques such as replacing the original wooden roof structure with new reinforced concrete (RC) or steel elements, inserting RC tie-beams in the masonry and new RC floors, and using RC jacketing on the shear walls. The L'Aquila earthquake revealed the numerous limitations of these interventions, because they led to increased seismic forces (due to greater additional weight) and to deformation incompatibilities of the incorporated elements with the existing masonry walls. This paper provides a discussion of technical issues pertaining to the seismic retrofit of the Santa Maria di Collemaggio Basilica and in particular, the limitations of the last (2000) retrofit intervention. Considerable damage was caused to the church because of questionable actions and incorrect and improper technical choices. [ABSTRACT FROM AUTHOR]

The European building stock consists of a large number of unreinforced masonry structures. Masonry structures proved themselves to be fragile if subjected to horizontal loads, particularly out-of-plane. The complexity of existing structures during an earthquake increases if they are arranged in aggregates. This research deals with the definition of vulnerability and fragility curves for Croatian existing masonry buildings in aggregates. The curves were derived following the European macroseismic scale (EMS–98). The adopted case study includes three aggregates located in Lower Town in Zagreb, Croatia. The capital of Croatia was hit by a series of earthquakes in March 2020. Until these recent earthquakes, the damage database from previous earthquakes was non-existent. The structural vulnerability was mainly assessed by analytical methods, which were not a proper solution for identifying the seismic risk on a larger scale, ultimately at the state level. The database from this earthquake series enabled the application, validation and calibration of empirical methods. The macroseismic index-based method was applied and based on the observed damage, new formulations to assess the vulnerability are proposed. [ABSTRACT FROM AUTHOR]

Many countries exposed to high levels of seismic risk, including Italy, are facing a huge challenge in promptly quantifying post-earthquake damages to their built historical heritage. In this context, structural health monitoring plays a fundamental role allowing to continuously track changes in selected damage-sensitive features. However, monitoring data interpretation is often not univocal and may be affected by large uncertainty, provoking false positives and false negatives. Hence, this research proposes a novel approach for post-earthquake structural condition assessment by exploiting the aggregation of different sources of information, notably steering from both monitoring and visual inspection campaigns, in order to take risk-informed decisions. More in depth, an automatic tool is proposed to detect and locate structural damages in monumental structures with the aid of a data fusion approach including vibration-based system identification, static and dynamic measurements, finite element (FE) and surrogate modeling, Bayesian-based model updating and visual inspections. In a preliminary phase, potential damage-sensitive regions in the structure are identified through FE-based numerical analysis and engineering judgment. Then, the solution of the inverse problem aimed at deriving the Bayesian posterior statistics of the uncertain parameters is entrusted to a computational-effective surrogate model (SM). Finally, the Bayesian-based updated parameters are adjusted considering the different allowable sources of information to achieve a final assessment. The effectiveness of the proposed approach is demonstrated by using the recorded data acquired in the Consoli Palace, an historical building located in Umbria, central Italy, which has been continuously monitored since 2017 using dynamic, static and environmental sensors and which has been hit by low-intensity earthquakes in 2021. [ABSTRACT FROM AUTHOR]

On 21/7/2017 a M6.6 offshore earthquake shook the Greek island of Kos and the Turkish coastal city of Bodrum. The Gazi Hasan Pasha mosque, a 1786 structure, suffered very limited damage: the load-bearing walls have not shown cracks or extensive deformation; the minaret and few timber members at the roof and the floor suffered serious damage. Confirmation of the damage by the results of an analysis under the nearby recorded seismic loads validated both the model and the assumptions of the analysis. In the second step the seismic performance was assessed using seismic loads from the Greek National Annex to EN1998-1 and the effectiveness of strengthening measures to upgrade the monument was studied. The assessment was based on the Greek code for interventions to masonry structures (KADET) which employs performance-based criteria. The analyses show that the mosque with strengthening measures implemented after it was damaged by an earthquake in 1933, withstands the relative drifts caused by the 2017 event. The predicted damage concurs with the observed limited damage of the structure. Analysis using seismic loads from Eurocode 8 and the performance- and displacement-based criteria of the draft KADET led to the conclusion that the structure cannot withstand these loads and needs strengthening. Insertion of steel tendons at the crest of the most displaced wall attenuates but does not eliminate the damage; addition of further tendons at the level of the top of the ground story wall appears to be very effective in achieving Immediate Occupancy performance for most elements of the building. [ABSTRACT FROM AUTHOR]

For rational solutions against seismic excitations of masonry bridges, the capability of 3D soil–structure interaction (SSI) modeling with experimental evidence has been insufficiently researched up to now. This is also valid for the effects of near- and far-fault earthquakes. Hence, the spectral responses measured by microtremors have been compared with the ones of 3D SSI analysis under the effects of near- and far-fault earthquakes for a historical masonry arch bridge in this article. The 3D SSI modeling of bridge and substructure soil was built with elastic finite element model using solid element and viscous boundary. The SSI analysis has been performed by direct approach using time-history analysis. The earthquake motions (near fault, far fault) were selected in accordance with the tectonic setting of the bridge's region. From the study, it is possible to confirm that microtremors are able to detect spectral responses of the bridge by the presence of SSI influences. By the evidence of amplifications and soil–structure resonance, the microtremor measurements experimentally promise that: (i) the bridge can be adequately identified by SSI analysis compared to fixed base, (ii) the elastic model can satisfactorily provide information about the bridge's responses (amplitudes, spectral response, stress distribution) under earthquake effect, and (iii) the far-fault motion especially due to SSI modeling is significant for the seismic responses. The study indicates that regarding the SSI influences into seismic computation has become quite efficient for determination of a possibility of various adverse effects (high displacements, critical stresses, resonance). Moreover, diagnosing the historical bridge well as a result of microtremors together with SSI modeling strongly proposes protection of the bridge with an appropriate retrofitting. [ABSTRACT FROM AUTHOR]

This study focuses on the seismic vulnerability of masonry buildings damaged by the 2009 L'Aquila earthquake. A geo-referenced database of 32,520 masonry residential buildings was compiled in the aftermath of the earthquake under the coordination of the Italian Department of Civil Protection through the AeDES survey form. The availability of this enormous amount of data provides an exceptional opportunity to examine in depth damage data and their correlation with the main parameters available from the post-earthquake survey. The original database was grouped into 20 building classes, defined as a function of vertical and horizontal structural types. Damage levels defined according to the European Macroseismic Scale classification are used to derive damage probability matrices and relevant vulnerability curves for these classes. The influences of connection systems, the quality/regularity of the masonry wall layout and the horizontal structural type on the building response are analysed in detail. A vulnerability classification, also supported by the use of statistical post hoc tests, is used to detect a reduced number of independent classes. The parameters of the non-crossing fragility curves are determined via the maximum likelihood estimation method by adopting a lognormal cumulative function to determine the exceedance probabilities of the considered damage levels. The impact of "mixed" classes, characterized by multiple vertical and/or horizontal structural types, on the derivation of the fragility curves is also investigated. Finally, the adaptation of the general version of the fragility curves to large-scale applications based on poor (census) data is also demonstrated, leading to curves that are easily usable in regional/national seismic loss assessments. [ABSTRACT FROM AUTHOR]

Churches struck by the earthquake sequence of 2016–2017 in Central Italy confirmed their seismic vulnerability, significantly higher than the one of other unreinforced masonry structures. This resulted in a much wider area affected by significant damages to churches, which were characterised by a rich variability of materials, typologies, dimensions and styles. In the area where significant damages were observed for ordinary buildings, most of the churches exhibited total or partial collapses. The time sequence of the main shocks helped in preventing casualties in churches although the collapse of a bell-gable in Accumoli caused victims in a neighbour house during the first event of August 24th, 2016. Damage surveys to churches were carried out on more than 4000 buildings, in a land area of about 30 000 km2 from September 2016 to May 2017. The data collected during the post-earthquake surveys represent a valuable source of information for better understanding the vulnerability of these structures as well as the effectiveness of past retrofitting interventions. Some examples are reported to show both damage progression due to the cumulated effect of repeated shaking and state-of-the-art strategies for short-term countermeasures. [ABSTRACT FROM AUTHOR]

Between August 2016 and January 2017 nine shallow earthquakes ranging from 5.0 and 6.5 of moment magnitude affected Central Italy, involving several municipalities wherein unreinforced masonry buildings are more than three quarters of all constructions. Damage state has been very severe, with sixteen settlements belonging to the municipalities of Amatrice, Arquata del Tronto, Accumoli, Castelsantangelo sul Nera and Norcia experiencing a cumulative European macroseismic scale intensity larger than IX. Ground motion demand in terms of peak ground velocity was approximately two or three times what expected for a 475 years return period while the pseudoacceleration response spectra showed values between once and twice gravity acceleration for the period range typical of two and three storeys unreinforced masonry buildings. Moreover, since October 2016, such large seismic demand acted on structures damaged from previous shocks testifying the effects of damage accumulation, too. The significant shaking alone cannot explain the extremely severe damage of some settlements, with large portions of whole blocks completely collapsed, highlighting the need for investigating the specific vulnerability factors and construction features of unreinforced masonry buildings in the affected area. In fact, although some deficiencies already highlighted in previous Italian earthquakes (e.g. inadequate structural connections) have been surveyed also during this sequence, a marked vulnerability of masonry and its mortar has been noticed, in particular in the area between Amatrice and Arquata del Tronto. On the contrary, the historical constructions in Norcia performed much better, as a result of the 1860 seismic code and of the retrofitting interventions implemented after the different earthquakes occurred in the last two centuries. Finally, a number of demolished and rebuilt constructions performed very well, and this was also the case also of modern hollow clay blockwork buildings that protected not only human life, but also cost of construction and continuity of use. [ABSTRACT FROM AUTHOR]

On 21st August 2017, an earthquake (ML3.6; MW3.9; Md4.0) struck the municipality of Casamicciola Terme on the island of Ischia, Italy. It was a peculiar earthquake: low magnitude, very superficial (focus depth of about 1.7 km), centered in a high population density area. Despite the island was historically struck by destructive earthquakes during the last centuries, buildings vulnerability in the area was high. Many masonry buildings (main structural typology in Casamicciola Terme and on the island) collapsed or were severely damaged, occasionally exposing the original, dating back to end of nineteenth century, wooden frame that is one of the first examples of code designed anti-seismic structures in Italy. In this study, preliminary data and field observations of the 21st August 2017 Ischia earthquake are given. First, data from the permanent seismic network are used to assess seismic input characteristics and compare them to the known seismic hazard. Building vulnerability is then analyzed via the results of field observations carried out soon after the seismic event, thus providing significant information about quality of materials, construction techniques, structural performance and interpretation of possible damage mechanisms. [ABSTRACT FROM AUTHOR]

The main objective of this study was to estimate the damage rate of steel and masonry buildings for different regions of Taiwan from future earthquakes according to the empirical data of 1999 M 7.6 Chi-Chi earthquake, Taiwan. The results are presented in quadratic equation relating building damage rates with modified Mercalli intensity. It is found that two zones are subject to high building damage rates. One zone extends from Hsinchu southward to Taichung, Nantou, Chiayi, and Tainan in western Taiwan, and the other extends from Ilan southward to Hualian and Taitung in eastern Taiwan. These zones are also characterized by low b values and also coincide with high peak ground shaking parameters. We also present the damage rates as function of waiting time for steel and masonry buildings in ten main metropolitans of Taiwan. The results show relatively low expected damage rates in Hengchun, Tainan, and Kaohsiung. But relatively high damage rates are found for most other areas. These results should be of use to government regulators and practicing engineers to enforce appropriate building codes to effectively mitigate potential seismic hazards. [ABSTRACT FROM AUTHOR]

In the framework of PERPETUATE, LOG-IDEAH: 'LOGic trees for Identification of Damage due to Earthquakes for Architectural Heritage' has been developed as a post-earthquake assessment tool for the evaluation of the global seismic performance of architectural assets (AAs). LOG-IDEAH is an expert system which interprets the seismic damage collected on site by relying on the knowledge of engineers and architects in seismic vulnerability assessment. The present expert system has been set up on logic trees, implemented in answer set programming to encode the recognition process that surveyors proceed to investigate the causes of damage and to evaluate the failures occurring on an AA. LOG-IDEAH, available at (), allows sketching AAs, recording the state of damage, uploading GPS referenced images and comparing collapse mechanisms observed on site with collapse mechanisms identified by the system. The seismic damage, which is the minimum data required by LOG-IDEAH, is collected at the level of both structural elements and artistic assets (local level) and interpreted at the level of the AA (global level). The answer set programming applied for the construction of the machine-processable representation, once the input data has been recorded into the web-interface, provides all possible failure modes and related possibilities of occurrence by taking into consideration the reliability level of the collected data. Its capability has been validated by applying LOG-IDEAH to the historic centre of L'Aquila of the 2009 earthquake by pointing out that answer set programming is a valid alternative approach to the existing methods developed to identify the seismic performance of masonry AAs. [ABSTRACT FROM AUTHOR]

Within the framework of PERPETUATE project for the case study in Slovenia, the 150 year old Kolizej Palace in Ljubljana was set. The building was for a long time neglected and severely deteriorated due to ageing and moisture problems. Despite the overall opinion among conservators upon its preservation, it was set to be demolished. Prior it's demolishing in 2011 extensive on-site investigation was carried out, which provided valuable data regarding the influence of deteriorated masonry on the seismic response of the building. Experimental tests proved almost completely saturated moisture conditions in the ground level of the building, while all the stories above were in almost dry condition. The results of tests on masonry revealed that moisture content and state of deterioration affected both strength and stiffness properties of built masonry in large extend. Regardless adopted modelling strategies the vulnerability assessment of the Kolizej Palace has proved that the building in its latest condition was far behind the current code requirements in respect to both static and seismic actions. [ABSTRACT FROM AUTHOR]

Worldwide cultural heritage and especially the heritage buildings in Europe are masonry buildings. Such buildings are generally capable to resist vertical loads but horizontal earthquake actions are often critical. The strengthening upgrade is generally required. One of the most promising methods for the strengthening of masonry walls is application of fibre reinforced polymers (FRP) to the surface of the wall. Three sets of the experimental research were performed recently with new innovative configurations of the fibre reinforcement placement on clay brick masonry. Within the framework of European FP7 research project PERPETUATE two sets of in-situ experiments were performed on 12 walls, belonging to two buildings approximately one hundred years old. Both buildings were made of solid bricks in low strength mortar. Third set of tests was performed in the laboratory on 16 specimens made of contemporary solid bricks in good lime-cement mortar. Tests were performed with different reinforcement configurations. Carbon FRP strips were epoxy-bonded horizontally, diagonally or combined (horizontally and vertically). Glass FRP grids were placed in the modified cement mortar over the entire surface of the wall. Specimens were tested under the constant vertical load and by a displacement controlled horizontal cyclic loading. The carbon fibre reinforced polymer strengthening significantly increased the ultimate displacement capacity in case of the horizontal and combined strengthening. The diagonal strengthening was not so effective because the failure of the diagonally strengthened specimens was governed by the peeling of strips from the masonry. The GFRP grid configuration greatly increased the load bearing capacity but not also the ultimate displacement. The shear strength of the strengthened and un-strengthened specimens was compared to the calculated values of the seismic shear load bearing capacity. For that the Triantafillou (J Compos Constr 2(2):96-104, ), Triantafillou and Antonopoulos (J Compos Constr ASCE 4(4):198-205, ), Marcari et al. () and Wang et al. (Asian J Civil Eng Build Hous 7(6): 563-580, ) calculation models and the design guides ACI 440.7R-10 () and CNR-DT 200/2004 were used. [ABSTRACT FROM AUTHOR]

The effect of uncertainties regarding modelling choices and knowledge of specific structural configurations on the seismic vulnerability evaluation of masonry buildings in Slovenia were studied using two case studies: a set of damaged buildings from the rural area of NW Slovenia hit by earthquakes in 1998 and 2004 and the urban buildings from the historic city centre of Ljubljana. Two modelling strategies were applied-failure mechanisms analysis by means of macro element methodology (MEM) and non-linear response analysis by means of structural element modelling. The accuracy in predicting failure modes by MEM ranged between 50 and 80 % of the stock of building in rural area. The most critical failure mechanisms were due to out-of-plane loading. Given the uncertainties associated with the data relative to the urban architecture stock, the MEM analysis was carried out considering different hypotheses, leading to a range of 30-70 % damaged buildings, for 475 years return period, with diverse failure mechanisms and ultimate capacity depending on specific structural assumptions. For one building of rural architecture already damaged during previous earthquake in 2004, where due to the extensive in-situ campaign the influence of uncertainties were minimised, direct comparison of the effectiveness of both methods were investigated. MEM assessment yields more conservative results in respect to non-linear approach and thus may be an efficient tool for the design of strengthening measures for heritage buildings to prevent damage in lower intensity events with higher probability of occurrence. [ABSTRACT FROM AUTHOR]

Timber-framed wall buildings are seen all over Europe, especially in seismic regions, given its adequacy to resist earthquakes. The pombaline buildings, developed after the big 1755 earthquake that destroyed Lisbon, constitute one of the best examples of ancient seismic-resistant structures based on timber-framed masonry walls. But in addition to suffering natural degradation and frequent inadequate interventions, these buildings were not prepared to resist the severe seismic actions envisaged by today's structural codes. In this context, they increasingly have to undergo rehabilitation and reinforcing works. The success of these projects strongly depends on the accuracy of the structural modelling, which in turn depends on knowledge of the behaviour of the existing structure. Aiming at providing reliable data to be used in structural design, a series of tests was carried out on the base element that constitutes the timber-framed masonry walls: the Saint Andrew's cross. The experimental tests were numerically simulated in order to determine the parameters that lead to the most accurate results when using linear-elastic models. [ABSTRACT FROM AUTHOR]

Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthquake events. It is known that their brittle behavior, which is mainly due to the combination of low tensile strength, large mass and insufficient connection between structural elements, is the main limitation for their structural implementation in residential buildings. A new construction system for masonry buildings using concrete blocks units and trussed reinforcement is presented here and its seismic behavior is validated through shaking table tests. Dynamic tests of two geometrically identical two-story reduced scale (1:2) models have been carried out, considering artificial accelerograms compatible with the elastic response spectrum defined by the Eurocode 8. The first model was reinforced with the new proposed system while the second model was built with unreinforced masonry. The experimental analysis encompasses local and global parameters such as cracking patterns, failure mechanisms, and in-plane and out-of-plane behavior in terms of displacements and lateral drifts from where the global dynamic behavior of the two buildings is analyzed comparatively. Finally, behavior factors for the design recommendations in case of unreinforced masonry are also evaluated. [ABSTRACT FROM AUTHOR]

Recent earthquakes, that stroked Italian regions in past decades (Umbria- Marche 1997; Molise 2002; L'Aquila 2009), pointed out the high vulnerability of reinforced concrete existing buildings causing severe damages in the structures and consequently life losses. This is mainly due to the fact that such structures were often built without reference to seismic actions or on the basis of old standard provisions. Nowadays in Italy, Public Authorities are requested to evaluate the seismic vulnerability of their building stock assessing the actual capacity of such structures, as a consequence of new hazard levels and seismic microzonation introduced by new standards. According to Eurocode 8 or Italian standard NTC 2008, the seismic analysis of existing reinforced concrete buildings can be performed by one of the established procedure (i.e. Linear Static Analysis LSA, Linear Dynamic Analysis LDA, Nonlinear Static Analysis NSA, Nonlinear Dynamic Analysis NDA), depending on the achieved knowledge level about the structural system and materials. In order to compare efficiency and differences of previously described approaches, a deep investigation was executed on a reinforced concrete existing building whose dynamic behaviour was evaluated by an experimental dynamic analysis. In such a way, updated models were obtained and adopted for seismic analysis performed by using linear and nonlinear approaches, taking into account the stiffness and strength contribution of masonry infill walls. It was so possible to get useful indications on the reliability and discrepancies of different modelling approaches as well as on the influence of masonry infills on the seismic response of existing r.c. buildings. [ABSTRACT FROM AUTHOR]

Between the late nineteenth century and the early twentieth century, Barcelona was expanded, occupying the terrains connecting the old walled city and the nearby towns of the plateau of Barcelona. At that time, a large number of unreinforced masonry buildings were constructed and nowadays many of them are still used as dwellings. Though built individually, these buildings are connected to adjacent buildings, forming blocks composed of aggregates. In order to analyze the seismic behavior of isolated buildings and aggregates, two typical central buildings and one typical corner building have been chosen. The two central buildings and the corner building are referred as C1, C2, and E buildings. Two corner buildings and two central buildings have been connected in order to simulate a block side. This aggregate is referred as AGG and it is composed by the following sequence of individual buildings: E- C1- C2- E. Original plans and drawings of existing buildings are then used to model these buildings. The modeled buildings have five stories. Standard pushover analyses lead to evaluate their seismic performance by means of capacity spectra and fragility curves. The analysis has been carried out in the parallel (Ux) and transversal (Uy) directions to the street. Then, a capacity spectrum based method is used to analyze the seismic behavior of these buildings considered as individual buildings and as an aggregate. Two earthquake scenarios are considered. The first one is a deterministic scenario which is based on a historical earthquake occurred in 1,824, 25 km away from the city and the second one is a probabilistic scenario, which represents the ground motion with a probability of occurrence of 10% in 50 years. The soil local effects have been also considered and both scenarios have been used to assess the expected damage. Four non-null damage states are considered: slight (1), moderate (2), severe (3) and extensive-to-collapse (4). For the type of soil where most of the buildings are, and in the Ux direction, the four buildings show a similar behavior. The mean damage grade is 2.3 for the deterministic scenario and 2.7 for the probabilistic one. This means that moderate to severe damage is expected in both cases; furthermore, in the case of the deterministic scenario more than 10% of the buildings would suffer extensive-to-collapse damage and nearly 20% for the probabilistic scenario, confirming the high vulnerability of such buildings. The differences in the expected damage are due to the significant different characteristics of the response spectra of the earthquake scenarios in the range of the fundamental periods of the buildings. [ABSTRACT FROM AUTHOR]