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In the last thirty years, Seismic Structural Health Monitoring (S SP 2 sp HM) has received a growing interest from both researchers and professionals, and an increasingly high number of seismic monitoring systems are currently installed in various countries. Therefore, the paper B Liao et al. b shows that medium-quality accelerometers (MEMS-based instruments) can provide feasible solutions for cost-effective city-scale deployment and performances that are superior to those of sensor networks with high-quality accelerometers. Vibration-based damage identification techniques are thus an important decision support tool that is being investigated by several research groups using both data-driven and model-based approaches. [Extracted from the article]

Regional seismic risk assessment is necessary for designing effective seismic risk mitigation measures. In general, such risk assessment studies consist of three components: hazard, vulnerability, and exposure modelling. This paper lays the foundations for regional seismic risk assessment of the residential building stock in Serbia and addresses each of the three seismic risk assessment components, either by reviewing the existing or proposing novel models. First, a review of seismic hazard models and seismic design codes used in Serbia in the past 70 years was presented. Next, an overview of Serbia's population metrics and historical development of Serbian's residential building stock was presented to provide the context for the exposure model. Furthermore, the paper proposed a novel building classification for Serbia's residential building stock, which is based on the existing building taxonomies, but it has been adapted to account for the local building characteristics. Building damage patterns reported in past earthquakes in Serbia and neighbouring countries were reviewed as a basis for damage classification pertaining to building typologies included in the proposed classification. Finally, the results of a preliminary vulnerability model were presented in the form of expert-based fragility functions derived for buildings typical of Serbia's residential building stock. [ABSTRACT FROM AUTHOR]

Timber structures are important components of the architectural and cultural heritage. To enrich literature on reconnaissance and heritage preservation, this paper provides a comprehensive damage survey and assessment of the Shuanghe Confucian temple after the 2019 Changning earthquake Series. Confucian temple is a temple for the veneration of Confucius and the sages and philosophers of Confucianism in Chinese folk religion and other East Asian religions. The Shuanghe Confucian temple, which sits in southwestern China, was first built at about 1241, but have been gradually deteriorating and refurbished for 600 years. It has the supreme structural grade in ancient Chinese architecture and delicate local characteristics. On June 17th, 2019, an Ms 6.0 earthquake stroke Changning County, and another four earthquakes (aftershocks) with magnitude larger than Ms 5.0 took place in the next 20 days. The Shuanghe Confucian temple experienced very distinctive damage during the earthquake series. The paper first present sufficient ground motion information. Characteristics of the all the major structural components are also introduced along with their mechanical functions. Next, the damage of all the typical timber structural components, like roof overhangs drop, column rupture, column bottom lateral residual displacement, and non-structural components failure are carefully documented and assessed. The paper reveals two important aspects that some major damages of the Shuanghe Confucian temple occurred in aftershocks, and that the columns bottom lateral residual displacement was caused by eternal impact induced by adjacent wall collapse, instead of structural inner forces. Thus, this paper helps better understand the seismic performance of traditional timber structures and identify potential weaknesses which might have adverse influences on timber structures. Lessons learnt from the Shuanghe Confucian temple can be used in future to better protect other historical timber structures from earthquakes. [ABSTRACT FROM AUTHOR]

The October 30, 2020 Earthquake caused unexpectedly significant damage in İzmir considering its distance to the city. This paper evaluates the recorded ground motions, summarizes the performance of structures affected from the earthquake with emphasis on the reasons of damage. A detailed damage assessment was carried out by the Earthquake Engineering Research Center of Middle East Technical University to compile data on the damage of RC and masonry buildings. It was observed that majority of the damage was concentrated in the Bayraklı district due to its peculiar soil properties where many 7–10 story mid-rise RC buildings suffered heavy damage and collapse. The level of amplified ground motions combined with deficiencies of apparently non-code compliant buildings exacerbated the damage. The main reasons of damage were mainly attributed to the presence of soft stories, lack of proper detailing, poor construction quality, presence of heavy overhangs, and hence significant lack of code-compliance in essence. The influence of infill walls on seismic performance of deficient and inadequate buildings was clearly seen in this earthquake. This paper also discusses seismic code requirements in effect and their influence on the observed building performance. The recorded ground motions were compared with the code spectra to evaluate the performance of the buildings. The code response spectra were found to be well above the recorded ground motion spectra at the sites where significant damage was observed. [ABSTRACT FROM AUTHOR]

In Almaty, the largest city in Kazakhstan lying on a high seismic region, many residential buildings constructed during the Soviet Union are still in service. These buildings were not properly designed against earthquakes and special seismic detailing was not well considered according to the local design code. Therefore, this paper presents an analytical seismic assessment of two typical reinforced concrete moment frame residential structures constructed in this era, representing 812 buildings with almost identical construction materials, geometries, and structural details. Two-dimensional nonlinear models were developed for these buildings in each orthogonal direction based on the structural details collected from a Kazakh government agency. Incremental dynamic analyses were then performed using 24 historical strong ground motions with fault characteristics similar to those in the Almaty region. Structural global and local seismic responses were investigated. A new approach was proposed to define structural global inter-story drift limits at different damage states based on local seismic demands considering uncertainties of earthquakes and structural nonlinear dynamic responses. Based on these inter-story drift limits, the structural fragility curves were then developed to identify the damage probability of these buildings, which were further used to roughly estimate repair costs at different earthquake intensity levels. It has been found that these buildings are vulnerable to destructive earthquakes due to poor structural details. They possess a high probability of incurring extensive damage (high repair cost) or even collapsing (irreparable) at the earthquake intensity level, with a return period of 475 years or 2475 years, respectively. [ABSTRACT FROM AUTHOR]

This paper documents performance of cast-in-place reinforced concrete (RC) buildings in the Durrës municipality during Albania earthquake of November 26, 2019 (MW 6.4). Both mid- and high-rise RC buildings were affected by the earthquake, experiencing structural and/or non-structural damage and even collapse in some cases. The authors performed a reconnaissance study after the earthquake and were involved in seismic assessment of buildings in the affected area. Besides the observations related to physical damage of RC buildings, the paper also presents results of a statistical analysis of damaged RC buildings in the Durrës municipality. The discussion in the paper is focused on damage patterns and failure mechanisms that are relevant for the seismic response of RC structures. Most common damage pattern observed after the earthquakes was related to masonry infill walls, which experienced damage and failure in some cases, and affected the performance of adjacent RC columns due to the infill/frame interaction. Taller RC framed buildings (10 storeys and higher) were expected to have RC shear walls; however, these walls were reportedly absent in the damaged buildings of this type. In some cases, masonry infill walls (instead of RC shear walls) were used in the elevator shaft areas, which resulted in inadequate seismic performance. A case study has been presented to illustrate seismic behaviour of mid-rise and high-rise cast-in-place RC buildings in the November 2019 earthquake, and is based on post-earthquake field observations and a detailed seismic assessment of two earthquake-damaged buildings. Finally, relevant lessons and recommendations are presented in light of the observed performance of RC buildings. [ABSTRACT FROM AUTHOR]

The seismic peak interstory drift ratio (IDR) of RC columns following an earthquake is measured in this paper through surface crack image analysis. The succolarity, lacunarity and fractal dimensions of the crack patterns for damaged RC columns are considered as the quantitative representatives of the complexity and irregularity of the crack images. An extensive databank of 445 crack maps from cyclic experiments on 110 rectangular reinforced concrete column specimens with double-curvature deformation mode is collected and utilized for the development and validation of the proposed procedure. The research databank covers a broad series of structural and geometric characteristics. Eight predictive closed-form equations are derived aiming at estimating the experienced peak IDR experienced by the RC columns during a seismic event using the accessible structural data from the damaged column. Results reveal that succolarity dimension is a strong vision-based indicator of damage in RC columns. Finally, the methodology is demonstrated through a practical application for a real damaged column in 2017, M 7.3, Kermanshah earthquake. [ABSTRACT FROM AUTHOR]

This paper presents a seismic vulnerability analysis of historic brick masonry buildings in Vienna, Austria from the period of the Austro-Hungarian monarchy (1840–1918). The vulnerability study is based on comprehensive data from the devastating earthquake damage to the masonry buildings in Zagreb, Croatia on March 22, 2020, which are from the Austro-Hungarian monarchy and comparable to Viennese buildings from that period, as well as on comprehensive numerical structural analyses calibrated on in situ test series. The statistical analysis of the earthquake damage to the Zagreb masonry stock and the comprehensive numerical simulations, allowed profound conclusions about the proportional damage distribution over individual structural areas of the masonry buildings, considering construction-specific characteristics such as the building height, the structural regularity/irregularity or the construction type under the ground level. This study enhances the still limited knowledge about the vulnerability of the historic brick masonry buildings from the period of the Austro-Hungarian monarchy and allows extensive conclusions about the seismic vulnerability of these buildings. [ABSTRACT FROM AUTHOR]

Remote reconnaissance missions are promising solutions for the assessment of earthquake-induced structural damage and cascading geological hazards. Space-borne remote sensing can complement in-field missions when safety and accessibility concerns limit post-earthquake operations on the ground. However, the implementation of remote sensing techniques in post-disaster missions is limited by the lack of methods that combine different techniques and integrate them with field survey data. This paper presents a new approach for rapid post-earthquake building damage assessment and landslide mapping, based on Synthetic Aperture Radar (SAR) data. The proposed texture-based building damage classification approach exploits very high resolution post-earthquake SAR data integrated with building survey data. For landslide mapping, a backscatter intensity-based landslide detection approach, which also includes the separation between landslides and flooded areas, is combined with optical-based manual inventories. The approach was implemented during the joint Structural Extreme Event Reconnaissance, GeoHazards International and Earthquake Engineering Field Investigation Team mission that followed the 2021 Haiti Earthquake and Tropical Cyclone Grace. [ABSTRACT FROM AUTHOR]

This paper discusses and compares two recently developed methodologies for the prediction of damage accumulation in structures subjected to multiple earthquakes within their lifetime, one based on a regression model and one based on a Markov-chain based approach. A stochastic earthquake hazard model is considered for generating sample sequences of ground motion records that are then used to estimate the probabilistic distribution of the damage accumulated during the time interval of interest using the various methodologies. A simulation-based approach provides a reference solution against which the other methodologies are compared. Besides assessing the effectiveness and accuracy of the two methodologies, some improvements of the regression model are proposed and evaluated. The comparison between the methodologies is carried out by examining a reinforced concrete (RC) bridge pier model and using the Park–Ang damage index to describe the damage accumulation. The study results demonstrate the importance of considering the possibility of occurrence of multiple shocks in estimating the life-cycle performance of structures and highlight strengths and drawbacks of the investigated methodologies. [ABSTRACT FROM AUTHOR]

The motivation of this study stems from a retaining wall made of waste tires. The wall did not suffer any earthquake or tsunami-induced damage during the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan. This paper deals with a case study on this tire retaining wall. Results from a series of field and laboratory investigations are first described. A numerical simulation is also described in which whole tires were used as protective layers in an embankment. The results show that confining effect of each tire, friction between the tires, ductility, and damping inherent in tires contribute towards the excellent performance of the retaining wall during the earthquake loading. The case study also reveals that it is the isolation mechanism due to the vibration absorption capability of rubber particles in tires, which could protect tire retaining structure during the earthquake. [ABSTRACT FROM AUTHOR]

The definition of relationships between damage and losses is a crucial aspect for the prediction of seismic effects and the development of reliable models to define risk maps, loss scenarios and mitigation strategies. The paper focuses on the analysis of post-earthquake empirical data to define relationships between buildings' damage expressed as usability rating or as global damage state and the associated costs for repair (i.e. direct costs) or for population assistance (i.e. a part of total indirect costs). The analysis refers to the data collected on residential buildings damaged by 2009 L'Aquila earthquake. For different usability rating or damage states, the paper presents the costs expressed in terms of percentage with respect to the reference unit cost of a new building (%Cr and %Ca for repair and population assistance costs, respectively). In particular, the costs analysis refers to undamaged, lightly or severely damaged buildings classified according to usability rating (i.e. A, B-C or E according to Italian classification) or to five different global Damage States (DSs). DSs comply with European Macroseismic Scale (EMS-98) and derive from literature available matrices properly defined to convert empirical damage to structural and non-structural components into building global damage. The %Cr probability density functions and relevant statistics derive from the analysis of actual data of post-earthquake reconstruction process, while, to determine those related to %Ca, a deep analysis of population assistance types, person/month assistance cost for each assistance form, and a methodology to associate such costs to each building are herein presented and discussed. Finally, the paper presents a relationship calibrated on empirical data to directly correlate repair costs on a building with assistance costs to their occupants. The relationships between empirical damage and direct and indirect costs herein presented are of paramount importance because they allow reliable loss scenarios to be defined by simply using literature fragility curves (defined according to empirical or mechanical approaches) aimed at evaluating the probability of exceeding different usability rating or damage states of existing buildings. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for rapidly addressing the earthquake-induced damage identification task in historic masonry towers. The proposed method, termed DORI, combines operational modal analysis (OMA), FE modeling, rapid surrogate modeling (SM) and non-linear Incremental dynamic analysis (IDA). While OMA-based Structural Health Monitoring methods using statistical pattern recognition are known to allow the detection of small structural damages due to earthquakes, even far-field ones of moderate intensity, the combination of SM and IDA-based methods for damage localization and quantification is here proposed. The monumental bell tower of the Basilica of San Pietro located in Perugia, Italy, is considered for the validation of the method. While being continuously monitored since 2014, the bell tower experienced the main shocks of the 2016 Central Italy seismic sequence and the on-site vibration-based monitoring system detected changes in global dynamic behavior after the earthquakes. In the paper, experimental vibration data (continuous and seismic records), FE models and surrogate models of the structure are used for post-earthquake damage localization and quantification exploiting an ideal subdivision of the structure into meaningful macroelements. Results of linear and non-linear numerical modeling (SM and IDA, respectively) are successfully combined to this aim and the continuous exchange of information between the physical reality (monitoring data) and the virtual models (FE models and surrogate models) effectively enforces the Digital Twin paradigm. The earthquake-induced damage identified by both data-driven and model-based strategies is finally confirmed by in-situ visual inspections. [ABSTRACT FROM AUTHOR]

This paper investigates the role of the horizontal axial force on the in-plane shear and flexural strength of masonry spandrels subjected to seismic actions. Strength criteria included in the main national and international codes take into account for geometrical and material properties, but valuable considerations about the influence of the horizontal axial force are missing. Nevertheless, experimental programs and post-earthquake damage scenarios proved that the horizontal axial force within the spandrels can be also significant under seismic actions, especially when they are surrounded by strength and stiff vertical piers or when significantly compressed by the effect of tensile-resistant elements. As main purpose, the strength criteria proposed by the Italian code for the spandrels have been revised accounting for the effect of the horizontal axial force on its shear and flexural strength. A database containing experimental tests conducted on masonry spandrels was elaborated and used to compare experimental with theoretical results. Outcomes showed that the revised criteria match satisfactorily the experimental results when significant axial forces affect the spandrels, both in terms of strength and failure mechanism. Contrariwise, existing code formulations are representative for the spandrels subjected to low axial force such that rocking or pure shear mechanisms tend to prevail. [ABSTRACT FROM AUTHOR]

In the last decades, recent earthquakes have further highlighted the high vulnerability of non-structural components. Post-earthquake damage due to building envelope, equipment and building contents can lead to substantial economic losses in terms of repair costs and daily activity interruption (downtime). Moreover, non-structural damage can represent a life-safety threat for both occupants and pedestrians. These considerations confirm the crucial need for developing low-damage systems for either structural or non-structural elements. This paper aims to assess the seismic performance of glazed facade systems, widely adopted in modern buildings, focusing on point fixed glass facade systems (PFGFSs), also referred to as "spider glazing". In this work, a numerical investigation is developed to study the seismic performance of such systems at both local-connection level through a 3D FEM in ABAQUS as well as at global system level through a simplified lumped plasticity model in SAP 2000 to assess the overall in-plane capacity of the facade. Based on the local connection and global facade system behavior, a novel low-damage connection system is herein proposed, and a parametric study is carried out on the key parameters influencing the facade capacity. The benefits of implementing low-damage connection details are highlighted by an increase of the in-plane capacity of the facade system when compared to a traditional solution. To further investigate the potential of the proposed low-damage details in preserving the integrity of the facade system itself, non-linear time history analyses have been carried out on a case-study building equipped with the innovative PFGFSs. [ABSTRACT FROM AUTHOR]

Inerter-based passive control devices have great potential to efficiently mitigate damage to structures subjected to earthquakes as they can provide large added mass effects, while having a relatively small physical mass. The added mass effect of inerters is typically achieved through the conversion of translational motion to the rotation of a flywheel. In a clutch inerter damper (CID), energy transferred to the flywheel cannot transfer back to the structure. Despite this potentially advantageous behavior, few studies have considered the seismic performance of structures with CIDs. As a result, the effect of the device parameters (i.e., effective mass and damping), the ability of the device to delay yielding and collapse of the structure, and the relative effectiveness of the device in far-field and near-field earthquakes, which more often include a dominant pulse, are uncertain. This paper addresses these gaps in knowledge through a numerical study of SDOF structures. The numerical model considers the nonlinear behavior of the structure in addition to nonlinear behavior of the CID. Incremental dynamic analyses were performed with suites of recorded earthquake ground motions. The results of these analyses showed that the CID is typically significantly more effective than a comparable viscous damper. Also, while performance differences were observed for different earthquake types, the median performance is broadly similar. Overall, this work shows the CID is capable of delaying the onset of yielding and collapse and otherwise mitigating the effects of a wide range of types of seismic excitation; thus, further investigation on its use is warranted. [ABSTRACT FROM AUTHOR]

The regional seismic risk assessment plays an important role in the disaster prevention and mitigation. The accurate time-history analysis for a region provides an important data base for regional seismic risk assessment. However, an accurate calculation method is limited, then, its accuracy still lacks validation. Meanwhile, there is also a lack of risk assessment methods and indicators applicable to the regional accurate time-history analysis, both of which hinder the seismic risk assessment. In this paper, a regional-scale time history analysis-driven method is proposed for the quantitative evaluation of regional seismic damage risk and verified with a real earthquake damage survey. First, the regional time history analysis method is introduced, including the automatic modeling, response calculating, result analysis and 3-D visualization modules. Second, a calculation method for seismic damage degrees (DD) of buildings is introduced. Subsequently, the probabilistic models of each DD under the ground motions with a specific intensity are calculated based on regional-scale nonlinear time history analysis. Next, the concept of the three-level seismic damage risk is offered, then a determining workflow of seismic damage risks is proposed based on the code-abiding three-level design requirement. Afterward, the regional seismic damage index is suggested for the quantitative evaluation of earthquake-induced damage risk. Finally, the actual seismic damage database of 192 buildings in epicenter of Ludian Earthquake is established through on-site investigations, then used to verify the regional simulation's accuracy. Consequently, it could be an aid to accurately present seismic damage distribution assessments and effectively develop seismic risk mitigation strategies. [ABSTRACT FROM AUTHOR]

This paper introduces a framework to estimate the seismic response of buildings at a regional scale by using representative indicator buildings. A robust database of buildings is required in the proposed framework to provide high-level structural and site information of the buildings. In this study, a database of 234 reinforced concrete buildings with five or more stories located in the central business district of Wellington, New Zealand was selected as a case study. In a prior phase of the research, the buildings were clustered into typologically similar clusters and eight representative indicator buildings were selected, where an indicator building was the closest building to the mean cluster structural and site characteristics. In this work, the concept of using indicator buildings to estimate building response across each cluster is investigated. First, three-dimensional structural models of each of the eight selected indicator buildings from the Wellington database were developed using the opensource structural analysis program OpenSeesPy. Five models were developed for each indicator building: one nonlinear model, one linear model, and three linear supplementary models where the effective stiffness of the structural members were modified to represent the period range of all buildings across a given cluster. The supplementary models were used to develop a period correction relationship to modify the estimated drifts based on the spectral shape of the imposed ground motion. Ground motions from the 2016 Kaikōura and 2013 Seddon earthquakes in New Zealand, as well as the 1995 Kobe earthquake in Japan, were selected to evaluate the proposed framework. The relationships between predicted elastic and inelastic drifts were explored, and polynomial regression models were investigated to provide drift correction accounting for the spectral shape of the three earthquakes. Finally, the efficacy of the proposed framework in estimating the response of all buildings across all clusters and the applicability of this framework as a near real-time impact tool were demonstrated using post-earthquake damage reports from the Kaikōura and Seddon earthquakes. [ABSTRACT FROM AUTHOR]

This paper explores and validates the use of ground shaking scenarios generated via 3D physics-based numerical simulations (PBS) for seismic fragility studies. The 2009 L'Aquila seismic event is selected as case-study application, given the availability of a comprehensive post-earthquake database, gathering observed seismic damages detected on several building typologies representative of the Italian built environment, and of a validated numerical model for the PBS of ground shaking scenarios. Empirical fragility curves are derived as a function of different seismic intensity measures, by taking advantage of an improved statistical technique, overcoming possible uncertainties in the resulting estimates entailed by data aggregation. PBS-based fragility functions are compared to the corresponding sets of curves relying on updated ShakeMaps. The predictive capability of the adopted simulation strategies is then verified in terms of seismic damage scenarios, by respectively coupling PBS- and ShakeMap-based fragility models with the corresponding ground shaking scenarios. Comparison of observed and predicted damage distributions highlights the suitability of PBS for region-specific seismic vulnerability and risk applications. [ABSTRACT FROM AUTHOR]

Recent seismic events worldwide have demonstrated the high vulnerability of existing school buildings and the urgent need to have reliable tools for the rapid seismic performance assessment and damage and loss quantification. Indeed, the significant damage observed on structural and non-structural components may have a significant impact in terms of direct and indirect losses making critical the recovery of stricken communities. Although a significant amount of work has been done in developing fragility curves for the residential building stock, only few contributions clearly refer to school buildings that significantly differ in terms of the main characteristics from the residential ones. This research work proposes fragility curves for reinforced concrete and unreinforced masonry public school buildings typical of the Italian building stock, based on the damage observed in the aftermath of the 2009 L'Aquila earthquake. A comprehensive and unique database including data on damaged and undamaged school buildings (2037 records) in the Abruzzo region was built using data from four different sources. Due to limited amount of data, the fragility curves can be very sensitive to the method adopted for their derivation, thus three different approaches (i.e. empirical, empirical-binomial, heuristic) are considered in the paper and the results are compared. Finally, a direct comparison with fragility curves available in the literature for the Italian residential building stock is presented. [ABSTRACT FROM AUTHOR]

This study proposes predictive equations for estimating the peak-experienced drift ratio of unreinforced masonry walls based on the visual characteristic of the damages. In this regard, a comprehensive database comprised of 190 images associated with 30 unreinforced masonry walls at different drift ratios between 0.0 and 1.1 percent is collected, and the visual features of the progressive damages are extracted. Various image processing filters are implemented to the images to quantify the cracking length and crushing areas. The filters are capable of distinguishing different crack patterns, such as joint cracking and block cracking. In the following, four scenarios are introduced based on the accessible parameters of the damaged walls to perform the post-earthquake damage assessment. Predictive equations are proposed based on the apparent characteristics of cracking and crushing as well as the mechanical property of the walls and loading conditions. The models provide nonlinear regression equations for estimating the drift ratio with an R factor up to 90 percent. The peak drift ratio predicted by the proposed models of this paper is also attributed to the damage states using existing fragility models. The proposed framework of this study plays a crucial role in post-earthquake structural damage assessment to determine the updated damage state and performance level of the damaged unreinforced masonry walls. [ABSTRACT FROM AUTHOR]

The January 24, 2020 Sivrice-Elazığ (Mw = 6.8) earthquake occurred on the East Anatolian Fault zone. Main shock of this earthquake was occurred 20:55 at local time. The Peak Ground Acceleration was equal to 0.3 g at the epicenter (Sivrice district) of the earthquake. Even though the main shock was moderate, its effects on the structures were rather serious. The main shock caused significant damage and resulted in 41 casualties. 1540 buildings were damaged moderately, while 8519 buildings were damaged heavily and collapsed. This main shock effected four cities surrounded the epicenter due to its shallow earthquakes. The purpose of this paper is to summarize past and present seismic characteristics of the earthquake region. In addition, the aim of this paper is to summarize the seismotectonic of the region, the general characteristics of the earthquake and more specifically to report on the structural damage, and structural damage caused by the earthquake, observed during the site investigation. The damages were classified for reinforced concrete structures, masonry dwellings and non-residential structures. All distinguished earthquake induced failures and damages were discussed. Moreover, lessons learned were presented in this study. [ABSTRACT FROM AUTHOR]

The earthquake that took place at 03:56 local time on November 26, 2019, with Mw = 6.4, struck the west part of Albania and caused heavy damages to many public and residential buildings in the districts of Durres, Tirana, Lezha, Shkodra, Diver, Berat and the surrounding areas. Immediately after the earthquake, teams from the Institute of Earthquake Engineering and Engineering Seismology arrived and made rapid visual assessment of 169 damaged buildings in the affected area. During the inspection, severe damages to structural and nonstructural elements were found. This paper shows the analytical proof of the seismic behaviour of the structures in which damages were observed during visual assessment. Elastic (static and equivalent seismic force) analyses of elements were performed up to ultimate state of strength along with dynamic analyses of low-, mid- and high-rise buildings with different structural systems and characteristics corresponding to the period of their construction and the design legislation for such type of structures in Albania. The ductility and displacement capacities were defined for each of these groups of structures, while dynamic analysis was performed to define the displacements and the ductility caused by the real earthquake record and the intensity of the earthquake recorded in Durres. The results from the analyses confirm the behaviour of low- and mid-rise structures under this earthquake considering that damages observed on-site completely correspond to damages that occur under the displacements obtained from the analytical investigations. Since high-rise buildings were not found in the stricken region, their behaviour under an earthquake with the same characteristics as the one that took place in November 2019 was predicted applying the same methodology used for the low- and mid- rise buildings. [ABSTRACT FROM AUTHOR]

A new method for seismic design of structures with the aim of controlling earthquake damage to a prescribed level is presented in this paper. The method is specified for special moment frame buildings with vertical and horizontal regularity. The main idea is determining a design story drift in correlation to a selected damage index value. For this purpose, the Park-Ang damage index is correlated with the maximum story drift. Through performing several nonlinear dynamic analyses of selected moment frame steel structures and regression analysis, it is shown that such a correlation is possible for the studied building type by a simple linear relation. Beginning from a desired value of the damage index, the design story drift is calculated using the developed linear equation and the same buildings are designed using a displacement-base procedure. Results of the nonlinear dynamic analysis of the buildings show that the maximum story damage index under a suit of spectrum compatible ground motions is consistent with the selected initial damage index using the proposed procedure. [ABSTRACT FROM AUTHOR]

Ground motion amplitude, frequency content, and duration are commonly identified as the main features of seismic waves affecting structural demand. Among these parameters, earthquake duration can have a substantial influence on assessment of structural seismic demand. The paper proposes a new empirical model for predicting the significant duration of ground-motion records in Turkey. Significant duration is an important parameter in determining the damage potential of earthquakes and is defined as the time interval between two specific values of Arias intensity. The proposed model is as function of moment magnitude ( M w ), Joyner-Boore distance ( R jb ), time-averaged shear-wave velocity in the top 30 m ( V S 30 ), and fault mechanism ( F m ). In the regression process, a database consisting of 850 records from 408 earthquakes in Turkey is used. According to the physics of the problem, mixed effect regression is employed. Next, besides residual analysis, comparison of the mean values with the other prediction models are performed. The results of this study indicate that the new model is satisfactory while reliable estimates of significant duration could be assessed for the Turkish region. [ABSTRACT FROM AUTHOR]

This paper presents a novel hybrid-based methodology devoted to develop urban fragility curves and damage probability matrices to predict likelihood seismic damage scenarios for small and medium Italian urban centres, considering URM buildings only. The concept of urban fragility curve consists of a single curve mean-representative of the seismic fragility of an entire area accounting for the combinations of building classes and their percentage, then they differ from those typological. The methodology has been developed with reference to Rocca di Mezzo, a small Italian urban centre located in the central Apennine area, Italy. Based on CarTiS inventory, building classes have been firstly recognized and urban fragility curves, representative for damage scenarios at Ultimate Limit State, developed. To predict damage scenarios from low to high-intensity earthquakes, an approach to define multi-damage urban fragility curves and damage probability matrices has been also presented. To this aim, a damage scale suffered by building classes has been defined by converting the final outcomes of the AeDES form (used in Italy for post-earthquake surveys) in the damage levels provided by the European Macroseismic Scale (EMS98). Data coming from urban fragility curves have been compared with the actual damage scenario recorded in Rocca di Mezzo after the 2009 L'Aquila's earthquake, in terms of both peak-ground acceleration and Mecalli-Cancani-Sieberg scale. The achieved results showed a good accordance between theoretical predictions and actual damage scenarios, coherent also with the damage scenarios occurred in other Italian historical centres hit by severe earthquakes over the years. Thus, the methodology can provide a first important indicator to support the development of emergently plans devoted to identify priority of interventions in such areas particularly vulnerable with respect to others. [ABSTRACT FROM AUTHOR]

This paper analyses the seismic vulnerability of various rammed earth medieval fortifications situated in Southeastern Spain, where seismic events with intensity over VII have taken place in the last millennium, using the vulnerability index method. This method begins with the choice of a certain initial value, V0, of the vulnerability index, which is obtained from a preset range between maximum, V 0 max , and minimum, V 0 min , values, which are likely for vulnerability indices, according to the constructive material characteristics and based on expert judgments. Rammed earth structures have not yet been studied using the vulnerability index method, despite the fact that they are quite common medieval structures in Spain and other countries in the Mediterranean region, many of which are also heritage sites, and hence are legally protected. Intervention priorities on them have been determined from the results in this paper with the aim of reducing their seismic vulnerability. For the different rammed earth techniques, a proposed primary value Vp = 0.76 together with some other material modifiers (construction typology and quality, current material porosity and density, and superficial deterioration) make the range of values V0 vary between 0.58 and 1.02. Moreover, structural behavior modifiers (MK) have been adapted to the various defensive rammed earth structural typologies used for these fortifications allowing us to obtain individualized vulnerability index values. Three rammed earth fortifications damaged by historical earthquakes and located in SE Spain have been used to validate the method, in which values of V0med range between 35.2 and 89.1% and upwards and the vulnerability index IVmed may vary between 27.9 and 70.7% and upwards as compared to those used by other authors for castles. Besides, the proposed method has been used by carefully choosing six rammed earth fortifications (two towers, two walls and two castles) in SE Spain which are representative of different construction systems, structural typologies and topographies. Furthermore, the mean damage grade and the probability of its occurrence is determined for each fortification based on PGA data and site effects, taking into account a probabilistic seismic scenario for a 975 year return period, in accordance with existing legislation. In the end, direct relations are established between the seismic vulnerability and the types of material and the typology of the fortifications. We have carried out a sensibility analysis in order to learn about the influence of the constructive technique, the material condition and the structural typology on the damage grade value. The results show that lime-crusted rammed earth technique and tower typologies are the most vulnerable structures while topography is somehow less important. The results suggest that for half of the structures analyzed for the given scenario the probabilities are above 80% for damage grade 4 and 5 (EMS-98). [ABSTRACT FROM AUTHOR]

Traditional sacrificial concrete shear keys are generally employed in highway bridges to restrain the excessive transverse displacements of the bridge superstructures and protect the substructures from being seriously damaged under the earthquakes. However, the post-earthquake rehabilitation or reconstruction of the conventional concrete shear keys are difficult and inconvenient. To this end, this paper proposed and designed a novel modified post-tensioned unbonded prestressing ultra-high-performance-concrete (UHPC) prefabricated retaining block (UHPC-PRB) structure with the straight joint connection. The novel UHPC-PRB structure consisted of a prefabricated UHPC retaining block, a prestressing anchorage system, and a cast-in-situ cap beam. The prefabricated UHPC retaining block was installed to the cast-in-situ cap beam using the unbonded prestressing tendons. The proposed UHPC-PRB structure is supposed to be effective in not only providing the same functionality as that of the traditional concrete shear keys, but also is expected of simplifying the retrofit procedure and reducing the rehabilitation expense simultaneously. To investigate the seismic behavior of the proposed UHPC-PRB structure, four test specimens were designed and the pseudo-static tests were carried out. The damage process, displacements, strains, and stress states of the specimens were studied. In addition, the influences of the loading height, thickness of the UHPC retaining block, and the initial tension of prestressing tendons on the seismic performance of the proposed UHPC-PRB structures were also examined. Finally, the experimental results indicated that, (i) the proposed UHPC-PRB structures had excellent lateral deformation capacity and self-resetting ability; (ii) the initial tension of prestressing tendons had significant effects on the lateral displacement, critical rotational load, and horizontal load-carrying capacity of the UHPC retaining blocks; (iii) the prestress loss of prestressing tendons had certain effect on the development of the bilinear analytical model of the UHPC retaining blocks, but this effect could be ignored in practical highway bridges; and (iv) increase of the horizontal loading height could reduce the critical rotational load and load-carrying capacity of the UHPC retaining blocks. [ABSTRACT FROM AUTHOR]

The diffusion of seismic structural health monitoring systems, evaluating the dynamic response of engineering structures to earthquakes, is growing significantly among strategic buildings. The increasing availability of valuable vibration data is being backed by continuously evolving techniques for analysing and assessing structural health and damage. Within this framework, the paper proposes a novel model-driven vibration-based methodology to support the assessment of the damage level in masonry buildings hit by earthquakes. The leading idea is to exploit, in the pre-event phase, synthetic equivalent-frame modelling and nonlinear dynamic analyses to systematically relate the gradual reduction of natural frequencies to increasing levels of structural damage. The resulting behavioural chart (seismic chart) of the building, constructed by employing computational tools and robustly defined on a statistical base, may provide the theoretical expectation to ascertain a certain level of seismic damage, based on the decrease in vibration frequency experimentally identified in the post-event phase. The methodology is firstly formalized, integrating common identification techniques with a novel damage grade estimation procedure, and finally exemplified for a monitored strategic masonry building damaged by the 2016–2017 Central Italy earthquake sequence. The outcomes of this application confirm the operational validity of the methodology, which can be intended as effective support for the decision-making process regarding structural usability and safety in the post-earthquake scenario. [ABSTRACT FROM AUTHOR]

This paper proposes a novel seismic vulnerability model for the classification of the existing residential building stock. The vulnerability model rests on a data-driven approach, taking advantage of observed seismic damages detected on several Italian building typologies, struck by the 2009 L'Aquila earthquake. Unsupervised machine learning techniques are exploited for clustering empirical damage data and objectively identifying vulnerability classes of decreasing vulnerability. The cascading use of different strategies, involving clustering analysis and probability theory, results in a comprehensive vulnerability model, which allows for determining, into a probabilistic framework, the degree of belonging of a given building typology to multiple vulnerability classes. The adoption of the peak ground acceleration for characterising the ground shaking is a further advantage of this study, overcoming several limitations related to the use of macroseismic intensity. [ABSTRACT FROM AUTHOR]

In recent years, the growing need for reducing non-structural damage after earthquakes has stimulated a dedicated effort to develop innovative types of fasteners for anchoring non-structural components (NSCs) to reinforced concrete (RC) host-structures. To contribute to such need, and building on previous research, this paper presents the results of a series of uni-directional shake-table tests of simulated NSCs anchored to concrete via: (1) expansion, and (2) chemical anchors; post-installed into: (a) uncracked, and (b) cracked concrete. Considering different construction details, the experimental investigation focused on traditional anchorage systems, alternative solutions comprising mortar filling into the gap clearance, and a low-damage system relying on supplemental damping devices, capable of reducing the acceleration of the NSCs as well as the force of the anchorage during seismic shakings. The experimental tests provided significant evidence on the beneficial effects of a dissipative anchorage protecting both the non-structural component and the anchorage itself, even during strong earthquakes. Moreover, when construction details allow to close the fixture clearance with a mortar filling, this stiffer solution provide an additional reduction of NSCs seismic accelerations and forces. Therefore, suggestions for further improvements of the adopted low-damage solution are also proposed. [ABSTRACT FROM AUTHOR]

Both the April 6, 2009 L'Aquila (Italy) earthquake, and the 2010-2011 Canterbury (New Zealand) earthquake sequence provided unprecedented opportunity to enhance the understanding on earthquake performance of infrastructure systems, and to analyse still-opened issues affecting the post-earthquake assessment and management of infrastructure. This paper provides a succinct and holistic overview on the physical and functional performances of the gas, water, waste water, road and electric networks (this one to a limited extent for the L'Aquila case-study), following the moment magnitude (M) 6.3 L'Aquila earthquake, and two main events of the Canterbury earthquake sequence, namely: the M 7.1 September 4, 2010 Darfield and the M 6.2 February 22, 2011 Christchurch earthquakes. A structured format, based on internationally recognised taxonomies and damage descriptors, is introduced to present the assets and to report on the earthquake-induced physical impacts for both above-ground and underground components. Functional impacts, interdependency issues and resilience attributes observed during the emergency management and recovery phases for the same infrastructure systems are furthermore discussed in the paper. It is envisaged that the data and overview on the seismic performance and management of infrastructure systems presented in the paper can be used to test the effectiveness of existing models and to inform the development of new models for seismic risk assessment and resilience analysis. Also, the structured framework presented within this paper can form the basis for defining specific and standardised survey tools for post-earthquake assessment of infrastructure systems. [ABSTRACT FROM AUTHOR]

Performance indicators such as energy, stiffness and displacement are the key parameters to evaluate the damage degree of structures or members subjected to earthquake. Establishing accurate and effective damage models based on these parameters is very necessary for performance-based seismic design. The current damage models have some deficiencies in dynamic mechanism, threshold range, accuracy and applicability. According to the mechanism of energy dissipation, it is assumed that the damage of structures and members is closely related to the difference between the ideal elastic–plastic deformation energy and the actual elastic–plastic deformation energy. This differential ratio can be used to represent the damage degree and damage evolution. Based on this, the damage model based on differential ratio of elastic plastic dissipated energy is proposed, and the specific calculation methods under monotonic static load, quasi-static load and dynamic load are given, respectively. Further, the damage index ranges corresponding to different damage grades are determined, and the application ranges and characteristics of different damage models are compared. The applicability and accuracy of damage model based on differential ratio of elastic plastic dissipated energy in members and structures subjected to different load are verified by damage assessment of the shear wall (static load), one 6-story RC frame structure (static load, seismic load) and one 12-story RC frame structure (shaking table test). The analysis results proved the damage model proposed in this paper has the advantages of clear mechanism, strict threshold, widely application range and can characterize the dynamic evolution of damage. [ABSTRACT FROM AUTHOR]

The creation of building exposure models for seismic risk assessment is frequently challenging due to the lack of availability of detailed information on building structures. Different strategies have been developed in recent years to overcome this, including the use of census data, remote sensing imagery and volunteered graphic information (VGI). This paper presents the development of a building-by-building exposure model based exclusively on openly available datasets, including both VGI and census statistics, which are defined at different levels of spatial resolution and for different moments in time. The initial model stemming purely from building-level data is enriched with statistics aggregated at the neighbourhood and city level by means of a Monte Carlo simulation that enables the generation of full realisations of damage estimates when using the exposure model in the context of an earthquake scenario calculation. Though applicable to any other region of interest where analogous datasets are available, the workflow and approach followed are explained by focusing on the case of the German city of Cologne, for which a scenario earthquake is defined and the potential damage is calculated. The resulting exposure model and damage estimates are presented, and it is shown that the latter are broadly consistent with damage data from the 1978 Albstadt earthquake, notwithstanding the differences in the scenario. Through this real-world application we demonstrate the potential of VGI and open data to be used for exposure modelling for natural risk assessment, when combined with suitable knowledge on building fragility and accounting for the inherent uncertainties. [ABSTRACT FROM AUTHOR]

This paper presents an overview on the response of the healthcare system in the area mostly affected by the 2016 Central Italy earthquake based on specific surveys and information from local health authorities. The authors collected in the field information on the seismic response capacity of the healthcare system. They surveyed five hospital complexes from medium to small dimension whose maximum capacity was up to 50 beds. This type of hospitals are representative of those ones present in the small towns located along the Apennines mountain range, usually including few buildings (i.e. 3–5) constructed in different periods and with different structural types. In all the surveyed hospitals there were partially or totally unusable buildings causing severe limitations to the functionality of the healthcare services, forcing to move many patients to other hospitals and to stop outpatient treatment. This was due mainly to severe damage to non-structural components and, in some cases, to moderate damage to structural components. In the present paper, two hospital case studies, namely "Tolentino" and "San Severino" hospitals, both located in Marche region, are analysed and discussed in detail in order to better understand their performance to the earthquakes, by also estimating their seismic risk via simplified methods, including the WHO Safety Index and the Cosenza and Manfredi (in: Fajfar and Krawinkler (eds) Seismic design methodologies for the next generation of codes, Balkema, Rotterdam, 1997) damage index. [ABSTRACT FROM AUTHOR]

The seismic assessment of the vulnerability of existing public structures, especially school buildings, is a crucial issue in seismic prone countries. Recently, several national and regional programs and activities have focussed on the mitigation of Italian public buildings. They promote the scheduling of public buildings' structural safety assessment and, when needed, the design and execution of strengthening interventions. Nevertheless, the three strong earthquakes that occurred in the last decade in Italy, Abruzzo (2009), Emilia (2012), and Central Italy (2016), confirmed the vulnerability of school buildings and the social importance of their quick re-opening after a damaging earthquake. In the present paper, the activities carried out on 1514 school building structures in the aftermath of the 2016 Central Italy earthquake sequence are reported and analysed. According to survey data collected by post-earthquake usability inspections, the paper analyses the school buildings characteristics, damage level and extent to structural and non-structural components as well as the correlation between seismic intensity and observed damage. [ABSTRACT FROM AUTHOR]

In the present paper a numerical study is reported, aimed at investigating the role of openings in the in-plane response of infilled RC frames when masonry infills with sliding sub-panels are adopted. Such innovative infills are meant to reduce post-earthquake damage and infill-frame interaction, with respect to traditional solid masonry infills. Their study was carried out mainly on the fully infilled configuration, and limited information is available about its response in presence of an opening. In the paper focus is made on the interaction of the infill with both the surrounding frame and with the specific post placed at the opening side, which is essential to confine the infill and protect the opening fixtures. The adopted numerical model is calibrated on the experimental results of a test performed on a real scale infill wall with horizontal sliding joints and a full-height opening on a side. A parametric study is carried out to investigate the influence of different design parameters. In detail, the focus is placed on the stiffness of the post and on the geometry of the infill (in terms of position of the opening, infill length and sliding joint configurations). The obtained results show the beneficial effect of the post deformability in reducing the infill-frame interaction, with a significant reduction of the shear action exerted on the frame columns and on the post itself. Moreover, the obtained results allowed to define some preliminary recommendations for the design of the infill and of the post at the opening side. [ABSTRACT FROM AUTHOR]

The post-earthquake damage assessment represents the first step after an emergency to support not only the safety of people, but also the preservation of buildings through the realization of prompt and effective provisional interventions. The issue is of particular relevance in case of monumental assets such as churches that are the focus of the paper. In Italy, since 1997 the post-earthquake damage assessment of churches has been carried out using a specific form, which was formally approved in 2001 by the Italian Civil Protection. Being the most advanced tool available in the literature within this specific field, the Italian form has been widely used also internationally. It follows the approach based on the decomposition of the church into macroelements. Although the latter has found wide confirmation through the interpretation of real damage, some critical issues were raised in relation to the versatility of the form and the reliability of the damage index that the approach provides. The post-earthquake damage assessment of 48 unreinforced masonry churches located in New Zealand, hit by the Canterbury earthquake sequence 2010–2011, represented an unprecedented opportunity, at international level, to investigate and to address the aforementioned issues. Starting from some weaknesses of the actual form, a new proposal (named CAF-D) for the damage assessment of unreinforced masonry churches has been developed and presented in the paper. The new form is still based on the macroelement approach, but it considers, in a separate way, the macroelements and the seismic damage modes they might develop, thus overcoming the limitation of the fixed number of damage mechanisms identified a priori by the current Italian form. The more reliable damage assessment approach that such form aims to achieve is the prelude to the development of a specific vulnerability model, derived by combining an empirical and an expert elicitation approach. A specific vulnerability model developed for New Zealand churches, derived by implementing the proposed CAF-D form and the related damage assessment procedure, is presented in the last part of the paper. [ABSTRACT FROM AUTHOR]

At 03:56 local time on November 26, 2019, an earthquake with a Mw = 6.4 struck western part of Albania. The duration of the tremor lasted less than 50 s and was felt largely also in Albania's capital Tirana, and in places as far away more than 300 km northeast of the epicenter. It caused damage to many public and residential buildings in districts of Durres, Tirana, Lezha, Shkodra, Diver, Berat and surrounding areas. This paper describes rapid visual assessment of the damaged buildings (169 in total) in affected areas by IZIIS teams' inspection of damaged buildings. Severe damages were identified in structural and non-structural elements as a result of inconsistent application of recent knowledge in design, construction and quality control of earthquake resistant structures. Structural errors in design and construction as well as inappropriate quality of built-in materials have been observed. Such results from the rapid damage assessment leads to the necessity of taking specific measures as detailed engineering inspection of vital structures as a basis of definition corresponding technical solutions for repair and strengthening with aim of restoring their operational mode. Last but not least, the biggest effect of earthquake damage was observed in non-structural elements which made the structures not-usable for citizens of the earthquake region. [ABSTRACT FROM AUTHOR]

Making a decision on the post-earthquake functionality of structures has always been one of the most challenging issues in earthquake engineering. There is an increasing trend toward resilient infrastructures that their post-earthquake functionality is planned so that the life and economic losses after the occurrence of earthquakes would be mitigated. Bridges, as the main elements of the transportation network, have received less attention in this regard. Deciding on the post-earthquake functionality of bridges is mostly subjective and based on the judgment of the inspectors. This paper aims to present an analytical-empirical decision-making framework for expediting the decision on the post-earthquake functionality of bridges that employs the damage data from inspections. The proposed framework is a two-phased probabilistic procedure that adopts the damage state and residual displacement of the bridge after the mainshock, and the possible aftershock characteristics as well. The link between the functionality of the bridge, allowed traffic, and the state of the damaged bridge is made with consideration of the uncertainties. The proposed framework is implemented on a sample bridge, and the decision procedure is illustrated. [ABSTRACT FROM AUTHOR]

In this paper, three different damage indexes were used to detect nonlinear damages in two adjacent Reinforced Concrete (RC) structures considering pounding effects. 2-, 4- and 8-story benchmark RC Moment Resisting Frames (MRFs) were selected for this purpose with 60%, 75%, and 100% of minimum separation distance and also without any in-between separation gap. These structures were analyzed using the incremental dynamic analysis method under 44 far-field ground motion records. Comparison of the results between the MRFs with and without considering pounding effects show that collisions lead to a decrease in the values of coefficient of determination and the nonlinear damage occurs in lower seismic intensity. As a result, using the damage indexes, nonlinear damages can be detected during a specific seismic intensity. Moreover, considering a minimum separation distance leads to an increase in the coefficient of determination between the damage index and the maximum story drift ratio. Furthermore, due to pounding, shorter MRFs are damaged more significantly than the taller structures. [ABSTRACT FROM AUTHOR]

The out-of-plane collapse of the façade represents one of the major threats and the most frequent cause of damages of churches due to strong earthquakes. Due to the slenderness of the façade and the lack of adequate connections to the side walls and the wooden roof, the seismic action can trigger the overturning. A detailed assessment is therefore required to judge whether or not to intervene. This paper presents an approach for the seismic assessment of the stability of the façade, through a discrete element model based on a photographic survey, with the aim of representing the actual geometry and arrangement of the stone units and their effects on the kinematics of the overturning. The collapse mechanism is simulated with both, quasi-static pushover and dynamic pulse-based analyses and the results compared to those of conventional rigid-body kinematics. The proposed approach is then applied to seven masonry churches that suffered severe damages during the 2009 L'Aquila (Italy) earthquake and the failure mode provided by the analyses is compared to the damages caused by the earthquake. The method is able to give a reliable estimate of the expected failure mechanism, taking into account the quality of the masonry and the connections to the side walls, while also providing the seismic acceleration required to trigger the motion and the ultimate displacement beyond which collapse occurs. [ABSTRACT FROM AUTHOR]

The development of building inventory is a fundamental step for the evaluation of the seismic risk at territorial scale. Census data are usually employed for building inventory in large scale application and their use requires suitable rules to assign buildings typologies to vulnerability classes, that is an exposure model specific for the considered vulnerability model. Several exposure models are developed proposing class assignment rules that are calibrated on building typological data available from post-earthquake survey data. However, this approach has the drawback of being based on data from specific geographic areas that have been hit by damaging earthquakes. Indeed, the distribution of building typologies can vary greatly for different areas of a country and the diffusion of one building's typology rather than another one may depend on the availability of construction material in the area, the evolution of construction techniques and the codes in force at the time of construction. This paper aims to improve the exposure modelling at regional scale, investigating the variability of masonry building typologies distribution. It proposes a methodology to recalibrate the exposure models at regional scale and evaluates the influence of the improved characterization of regional vulnerability on damage and risk assessment. The study shows that the analysis of local building typologies may strongly impact on the evaluation of the seismic risk at territorial scale. [ABSTRACT FROM AUTHOR]

The present paper deals with the elaboration of a methodology to assess the macro-seismic risk of monumental historical buildings, representing a fundamental part of the European cultural assets. Monumental buildings typically arise from a very complex constructive and morphological evolution process characterised by modifications occurred over the centuries. Therefore, they are usually heterogeneous buildings similar to 'structural aggregates' rather than single constructions and characterised by a structural behaviour depending on the mutual interaction of different structural units. An accurate knowledge process can allow the determination of structural units within the complex: such units can be therefore analysed using a specific evaluation form conceived to provide a 'risk ranking' of the different portions constituting the aggregate and accounting for vulnerability, exposure and seismic hazard parameters. The proposed methodology exploits what is already used to quickly determine structural features and eventual damages in the post-earthquake phase for ordinary buildings, introducing specific aspects typical of historical-cultural heritage requiring attention. According to the results achieved, retrofit interventions or deepen investigations can be planned for units provided by a higher position in the risk scale, optimising and rationally planning the use of available economic and time resources. In the present work, the proposed methodology is applied to the monumental complex of the Certosa di Calci, Pisa (Italy). [ABSTRACT FROM AUTHOR]

This paper describes CEQID, a database of earthquake damage and casualty data assembled since the 1980s based on post-earthquake damage surveys conducted by a range of research groups. Following 2017–2019 updates, the database contains damage data for more than five million individual buildings in over 1000 survey locations following 79 severely damaging earthquakes worldwide. The building damage data for five broadly defined masonry and reinforced concrete building classes has been assembled and a uniform set of six damage levels assigned. Using estimated peak ground acceleration (PGA) for each survey location based on USGS Shakemap data, a set of lognormal fragility curves has been developed to estimate the probability of exceedance of each damage level for each class, and separate fragility curves for each of five geographical regions are presented. A revised set of fragility curves has also been prepared in which the bias in the curve resulting from the uncertainty in the ground motion parameter has been removed. The uncertainty in the fragility curves is evaluated and discussed and the curves are compared with those from other studies. A resistance index for each class of building is developed and cross-regional comparisons using this resistance index are presented. [ABSTRACT FROM AUTHOR]

This paper presents seismic fragility assessment of RC high rise-buildings for seismic excitation, typical for Southern Euro-Mediterranean zone. The fragility curves were derived and log-normal cumulative distribution function parameters were obtained for the four defined damage states by conducting 3600 nonlinear time-history analyses on the basis of 60 ground motions with wide range of magnitudes, distance to source and different site conditions, including in this way uncertainties during ground motion selection. As a prototype buildings, 20-story, 30-story and 40-story RC high-rise buildings with core wall structural system were chosen. The key points of the process for obtaining the fragility curves are shown by using algorithm, defined in this paper, and generally applicable to all types of RC high-rise buildings. For the purpose of conducting nonlinear time-history analyses, non-linear 3D models of the buildings were designed. A detailed probabilistic seismic damage analysis was done and as its result the limit states as well as corresponding damage states for RC high-rise buildings were defined, where the damage states were treated as random variables. Inter-storey drifts at threshold of damage state were defined as random variables with the range of possible values. Since no probabilistic fragility curves exist for this class of buildings and for this seismic zone, this work partially fills the void in Southern Euro-Mediterranean seismic risk assessment. The whole approach presented in this paper may be used for efficient obtaining probabilistic fragility curves for RC high-rise buildings of different configurations. [ABSTRACT FROM AUTHOR]

In recent years, significant economic and human loses have been caused by earthquake events across the globe, particularly in developing countries, where non-seismically designed buildings constitute a significant share of the existing stock. Algeria is one of those cases and has witnessed earthquakes in the northern part of the country, which indicated the urgency to establish a robust disaster risk reduction strategy. Building exposure is one of the main model components for natural hazard risk assessment and, typically, exposure models are defined from proxies, such as national census databases or local expert opinion, for the distribution of buildings and population. However, no specific indications on the best nature or size of a regional exposure model are available to provide guidance on large-scale seismic assessment studies. In this paper, a step forward is provided by engaging different Algerian stakeholders in the collection of in-situ building data through a user-friendly smartphone/tablet application, with the aim of aiding the development of building exposure and vulnerability models, as well as increasing the risk awareness among local population and practitioners. Subsequently, earthquake damage estimates are produced and evaluated over the buildings' lifetime in terms of exceeding slight, moderate, extensive and collapse damage states. The computed damage metrics are also used to provide input on the importance and usefulness of the in-situ collected data as a supporting data source in the development of exposure and vulnerability models. A discussion on the possible sources and size of the exposure model and preliminary guidance on conducting in-situ surveys are provided, with a view to a possible re-use in other contexts (provinces) with similar building stocks to the region addressed in this study. [ABSTRACT FROM AUTHOR]

Conventional concrete frames are designed to dissipate the earthquake energy through inelastic deformation of the structural elements. It leads to hefty repairment costs and prolonged down time after earthquakes. Self-centering concrete frames (SCCF) have been introduced to minimize the unrecoverable structural damages and post-earthquake repairment costs. SCCF exhibits predictable yield mechanism and self-centering capacity. This paper presents an energy-based seismic design (EBSD) procedure for SCCFs. Based on a proposed damage model, hysteretic energy demand, EH, is introduced as a key design parameter. The desired damage state and structural deformations can be considered in design process. EBSD allows designers to select various performance objectives at different seismic intensities. A prototype building is designed using the proposed EBSD procedure. The performance of SCCF designed using EBSD is compared with the same prototype structure designed using direct displacement-based design method (DDBD). The results show that SCCF has high performance with low residual drift. The performance of the EBSD designed SCCF exhibits more controlled damage compared with the DDBD designed SCCF. [ABSTRACT FROM AUTHOR]

A hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions. Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building's class has been chosen as an Intensity Measure to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minimum value of PGAs defined for each building class. To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber macroseismic intensity scale has been used and the corresponding fragility curves developed. Results show that the proposed building's classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods. [ABSTRACT FROM AUTHOR]

The article focuses on earthquake reconnaissance missions and their benefits to earthquake engineering. Topics discussed in the article include achievements of early missions like the 1627 Gargano earthquake in Italy, contributions of UNESCO supported missions between 1963-1980 and modern post-earthquake field investigations along with investigating teams such as the German Task Force (GTF) and the Japanese Society for Civil Engineering (JSCE).