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This study investigates the effects of adjacent deep excavation on the seismic performance of buildings. For that purpose, the numerical models are constructed for different buildings (i.e., 5-Story building and 15-Story building) considering the deep excavation-soil-structure interaction (ESSI) and soil-structure interaction (SSI). The results achieved from the ESSI and SSI systems are discussed and compared. Fully nonlinear numerical models with material, geometric, and contact nonlinearities are developed. Eleven earthquakes with different intensities, epicentral distances, significant durations, and frequency contents are applied to the models; and, the numerical results are given in terms of average records. The buildings are carefully designed and verified based on common design codes. The numerical modelling procedure of the deep excavation-soil system is validated using centrifuge test data. The comparisons between the ESSI and SSI systems are carried out in terms of accelerations, lateral displacements, inter-story drifts, story shear forces, and the nonlinear behavior of the soil medium under the buildings. The results show that it is necessary to consider the ESSI effect, and it might significantly change the seismic behavior of buildings adjacent to the deep excavations. The findings from this study can provide valuable recommendations for engineers to design buildings close to deep excavations under earthquakes. [ABSTRACT FROM AUTHOR]

We present the results of probabilistic seismic hazard assessment for Iran based on a statistical procedure specifically developed to manage macroseismic intensity data. This method takes into careful consideration the specific features of such data, which are characterized as ordinal, discrete, and confined within a finite interval, ensuring a logically coherent approach throughout the analysis. The results of our assessment are then compared with hazard maps generated using a standard approach, putting in evidence significant differences both on a national scale and relative to individual cities. This comparative analysis will be useful in identifying areas of utmost concern, where further studies are strongly recommended to yield hazard estimates of greater robustness and reliability. By pinpointing these critical scenarios, we aim to guide future research endeavors towards providing more accurate and reliable seismic hazard estimates. Identifying these critical situations facilitates the prioritization of resources and interventions, ultimately enhancing seismic risk mitigation efforts across Iran. [ABSTRACT FROM AUTHOR]

In regions where strong earthquakes occurred before the deployment of dense seismic and accelerometric networks, intensity datasets can help select appropriate ground motion prediction equations (GMPEs) for seismic hazard studies. This is the case for the Hainaut seismic zone, which was one of the most seismically active zones in and around Belgium during the twentieth century. A recent reassessment of the intensity dataset of the area showed that intensities in this region attenuate much faster with distance than in other parts of northwestern Europe. Unfortunately, this characteristic has not yet been taken into account in current hazard maps for Belgium and northern France. Based on this dataset, we evaluate the goodness of fit of published GMPEs with intensities in Hainaut by means of a ground-motion-to-intensity conversion equation (GMICE) and according to different metrics (Likelihood, Log-likelihood and Euclidean-based Distance Ranking) published in literature. We also introduce a new measure to specifically evaluate the distance trend. Our results show that none of the tested GMPEs convincingly fits the intensity dataset, in particular the fast attenuation with distance. Nevertheless, applying the few GMPEs that show a reasonable fit in seismic hazard computations, we observe a decrease of the influence of the Hainaut seismicity on hazard maps for Belgium and northern France. This result is compatible with the earthquake intensity observations for the last 350 years in this part of Europe. [ABSTRACT FROM AUTHOR]

Masonry-infilled reinforced concrete (MI-RC) buildings are one of the abundant building inventories and are commonly seen because of their relatively cheaper construction materials, and easier workmanship. However, often due to the negligence of the design guidelines or disregard of the contribution of masonry infills in structural weight and stiffness, these buildings become seismically vulnerable. Generally, the design involves uncertain parameters related to material and geometric properties, a slight change of which may lead to large variation in the structural response. More specifically, the masonry infill wall parameters can result in huge structural response variation. The issue of variation in structural response becomes more critical considering the large uncertainty involved in the quantification of earthquakes and the ground motion parameters while conducting time history analysis. Usually, peak ground acceleration (PGA) is considered as the ground motion intensity measure (IM) to define the ground shaking. However, several other IMs, such as arias intensity, specific energy density, the ratio of peak ground velocity to peak ground acceleration, dominant frequency, and the strong motion duration can also influence and determine the severity of seismic damage caused to the buildings, explicitly in case of infilled RC frames. The present study is an effort to quantify the effect of several such ground motion parameters, on the response of masonry-infilled reinforced concrete frame. An attempt has also been made for modification of the established demand–capacity relationship, also known as IM versus EDP (engineering demand parameter) based on the relative frequency characteristics of the building and the ground motion. It is suggested that relating the EDP with multiple ground motion parameters considering the frequency characteristics of the building and the ground motion can give a more realistic picture of the effect of seismic vibration of such buildings. [ABSTRACT FROM AUTHOR]

In a recent work, we evidenced some empirical discrepancies between the macroseismic intensity estimates in Italy in the last decade with respect to those made previously. A possible reason might be the progressive adoption by Italian researchers of the European Macroseismic Scale (EMS) in place of the Mercalli Cancani Sieberg (MCS) scale mostly used up to 2009. In theory, in modern settlements where reinforced concrete (RC) buildings are increasingly replacing those in masonry, EMS should overestimate MCS because the former accounts for the lower vulnerability of RC whereas the latter does not because RC buildings were not considered at all by the MCS scale since they were almost absent at the time (1912–1932) when it was compiled by Sieberg. However, such theoretical inference is contradicted by the empirical evidence that, on average, MCS intensities really estimated in Italy over the past decade slightly overestimate EMS and not vice versa as it should be. A possible explanation is that the EMS scale had not been well calibrated to reproduce the MCS, as its authors intended to do. Another possible reason for the discrepancies between the last decade and the previous ones might be that the MCS scale applied today is not the same as that defined by Sieberg at the beginning of the twentieth century. In order to better understand the possible causes of such discrepancies, we present here a formal comparison between the definitions of the different degrees of such macroseismic scales. After such analysis, we might argue that another possible reason for the observed discrepancy may come from the inaccurate assessment of building vulnerability when assessing the EMS intensity. [ABSTRACT FROM AUTHOR]

In the general practice of performance-based seismic assessment and dynamic analysis of building structures, the recorded ground motions from past earthquake events are selected and modified according to the site conditions and hazard level of the project's site. For this purpose, only the mainshock earthquake event is considered for the analysis while neglecting the foreshocks and aftershocks. However, in several real cases, especially for existing RC buildings with non-seismic detailing, low- to moderate-magnitude foreshocks and aftershocks may also affect the seismic performance. Several studies have shown that the application of repeated earthquake events may lead to damage accumulation and significant seismic losses, even if the structure is at a life safety performance level. This study examines the seismic performance of mid-rise RC frame structures in Pakistan under repeated earthquakes. For this purpose, a representative case study building has been selected for the detailed analysis after surveying typical existing RC buildings in Pakistan. The detailed nonlinear finite element model is constructed and subjected to several cases of repeated earthquakes with different intensity levels. The seismic performance in terms of key demand parameters is evaluated for single earthquake scenarios (mainshock only) and seismic sequences (foreshock, mainshock, and aftershock). The results showed the application of seismic sequences has a negligible effect on the peak seismic force and displacement demands of the buildings compared to the single mainshock event. However, an increase in seismic performance indicators, including residual displacements and inelastic hysteretic energy, is observed. Resultantly, an increase in structural damage (quantified in terms of material cracking, yielding, crushing, etc.) is also observed for ground motion sequences compared to the single ground motion. [ABSTRACT FROM AUTHOR]

To overcome negative effects of traditional masonry infilling walls (MIWs) on the seismic resilience of a self-centering prestressed concrete (SCPC) frame, a novel SCPC frame with sliding infill walls (SCPC-SIW frame) is proposed. This study compares the seismic performance of the SCPC-SIW frame and the SCPC frame with MIWs (SCPC-MIW frame) through quasi-static tests, fragility analysis, and risk assessment. To begin, quasi-static tests on single-story SCPC-SIW and SCPC-MIW frame specimens are performed to compare their failure characteristics, hysteresis response, energy dissipation, and self-centering ability. The numerical simulation methods for SCPC-SIW and SCPC-MIW frame specimens are then presented and validated. Subsequently, two four-story SCPC-SIW frames and two four-story SCPC-MIW frames are designed, and their dynamic response under MCE is preliminary analyzed. Finally, the fragility analysis and risk assessment of these multi-story SCPC-SIW and SCPC-MIW frames are conducted to determine the probability of their peak inter-story drift ratio (PIDR), residual inter-story drift ratio (RIDR), and peak floor acceleration (PFA) exceeding the specified limit states under any intensity earthquake and within 50 years. The results indicate that, except for cracks caused by fatigue damage appearing on the SIW at the end of loading, the SCPC-SIW frame specimen remains undamaged, whereas the SCPC-MIW frame specimen exhibits diagonal step cracks on the MIW. The hysteresis curve of the SCPC-SIW frame specimen exhibits an ideal and repeatable flag shape, whereas the stiffness and strength of the SCPC-MIW frame specimen degrade during the test. Besides, the probability of exceeding the 4% PIDR and exceeding 0.2% and 0.5% RIDRs within 50 years for the SCPC-SIW frame is significantly lower than that for the SCPC-MIW frame. The SCPC25-MIW frame has a higher probability of exceeding the 1 g PFA within 50 years than the SCPC25-MIW frame. In other cases, the SCPC-SIW frame has a lower probability of exceeding 1 g, 2 g, and 3 g PFA within 50 years than the SCPC-MIW frame. [ABSTRACT FROM AUTHOR]

In the last decades, high priority has been given to enhancing the seismic resilience of structures by reducing the damage of structural and non-structural elements after a disaster. In this context, the European Research Fund for Coal and Steel (RFCS) project DISSIPABLE was funded to perform large demonstration tests of steel frames equipped with easily repairable seismic dissipative devices. The paper extensively describes the experimental campaign carried out at the University of Trento on a steel frame equipped with innovative Dissipative Replaceable Link Frame (DRLF) systems, composed of two rigid columns connected by weakened beams at their ends. Hybrid Simulation was employed, enabling to physically test the first floor of the building yet allowing for considering the response of the remaining five floors, which were numerically simulated. A bidimensional frame was tested under increasing seismic intensity levels: Damage Limitation, Significant Damage and Near Collapse limit states. The experimental results proved that the DRLF system was able to dissipate energy and protect the primary elements of the structure from plasticisation. Moreover, the structure's re-centring capability was verified to ensure the components' replaceability. Finally, the calibration of the nonlinear model was performed following the tests, which allowed to develop a high-fidelity model suitable for further numerical investigation. [ABSTRACT FROM AUTHOR]

Performance-based design establishes performance objectives in terms of earthquake intensities. Damage limit states depend on the building demands in the nonlinear range of behavior when subjecting the structure to a suite of seismic records. Most of world databases have strong-motions recorded from small- and moderate-magnitude earthquakes that need to be scaled when studying the expected building performance under maximum considered earthquake. Scaling accelerograms is a frequent activity in nonlinear analysis of structures, and different techniques based on several intensity measures have been used, without a general consensus to select the most appropriate scaling methodology. This study shows the variability in the seismic performance assessment of reinforced concrete buildings of different heights, symmetrical in plan and regular in elevation, on four seismic zones, when using scaled accelerograms for a maximum considered earthquake, assumed for a return period of Tr = 2500 years. Ten methodologies frequently used in the literature are analyzed to evaluate inter-story drift ratio and floor acceleration demands of buildings subjected to a suite of near-, medium- and far-fault interplate earthquakes. The results show different expected damage limit states as a function of the scaling technique used. Additionally, some scaling techniques consistently generate higher seismic demands regardless of the seismic location of the buildings, whereas another group produces quite similar demands. Moreover, a building could be placed in the slight damage limit state or in a zone of extensive damage depending on the scaling technique used. [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]

The ability of an intensity measure (IM) to accurately reflect the characteristics of ground motions is of utmost importance for seismic fragility assessment. Traditional investigations focused on selecting the optimal IM have primarily been conducted based on ordinary reinforced concrete (RC) structures. The direct application of IM specifically tailored for ordinary RC structures in the fragility analysis of self-centering prestressed RC (SCP-RC) structures will potentially introduce increased uncertainties of ground motions. This paper aims to conduct a comprehensive analysis to identify the optimal vector-valued IMs (vIMs) for the fragility assessment of SCP-RC structures. A total of eight vIMs were constructed by combining various scalar-valued IMs (sIMs) associated with the peak values and spectra of ground motions. A 5-story SCP-RC structure was designed to evaluate the efficiency and correlation of the established vIMs using a multi-parameter damage measure (mDM). Probabilistic seismic demand models for the eight examined vIMs were developed. A comparative analysis between the fragility surface slices obtained using the identified optimal vIM and the fragility curve derived from the corresponding sIM was performed. The results indicate that (PGV, I N p /PGV) is the most suitable vIM for accurately quantifying the fragility of SCP-RC structures. The seismic fragility surface is more efficient than fragility curve in estimating the seismic performance of SCP-RC structures. [ABSTRACT FROM AUTHOR]

This study aims at developing new macroseismic intensity attenuation models valid for Italy by exploiting the most updated macroseismic dataset and earthquakes catalogue, as well as the information obtained from a critical analysis of the most recent models in the literature. Several different attenuation models have been calibrated as a function of the moment magnitude (Mw) and epicentral distance from 16,260 intensity data points, that are related to 119 earthquakes occurred after 1900. According to trends and residuals analysis, the preferred calibrated intensity attenuation function is a Log-Linear model for epicentral distance (Repi in km) and a linear model for Mw as: I MCS = 1.81 - 2.61 L o g R - 0.0039 R + 1.42 M w with pseudo hypocentral distance R = R epi 2 + 9.87 2 ; the estimated standard deviation is σ = 0.75. Also noteworthy is another model for macroseismic intensity attenuation that proved to be as good as the best model and shows higher sensitivity to physical parameters, such as focal depth and magnitude, especially in the epicentral area. Performance of all calibrated models was also checked on an independent set of 15 post-1900 Italian earthquakes. One of the results of the present work is the opportunity to define earthquake scenarios (e.g. probabilistic seismic hazard maps) in terms of Macroseismic Intensity and its related standard deviation, avoiding the uncertainties due to the conversion of various ground shaking parameters into intensity values. [ABSTRACT FROM AUTHOR]

To comprehend the empirical seismic vulnerability capability of various typical structures in towns and suburbs, this study considers, as the research background, the structural damage data observation from the Mw 7.1 Yushu earthquake that occurred on 2010 April 14th in China. The proposed research activity sorts out the actual investigation data (7156 buildings) of five types of typical structures in towns and villages and establishes the vulnerability and seismic fragility evaluation model of a group of buildings considering multidimensional parameters by using the Chinese macroseismic intensity standard. Using spatial modal, numerical calculation, and regression analysis methods, an updated lognormal distribution vulnerability and resilience assessment model based on multidimensional quantitative parameters is performed. Based on the principle of the conditional probability and damage quantification model, an innovative model (domain, point cloud, curve, surface, matrix, and function) is established for regional vulnerability and seismic resilience assessment of typical group buildings. A logarithmic relationship model considering both the updated Chinese macroseismic intensity and three-dimensional composite peak ground acceleration as intensity measures is proposed, and an empirical vulnerability assessment model for typical rural buildings is established. The traditional average earthquake loss index calculation model is updated, and an innovative regional domain vulnerability assessment model is conducted. Taking the samples of various typical structures surveyed in the Yushu earthquake, regional group structure vulnerability domain comparison models of various structures are performed. Ultimately, depending on the typical damage characteristics of structures, the actual damage features and mechanisms of various structures are analysed. [ABSTRACT FROM AUTHOR]

Assessing the actual seismic economic losses of regional building portfolios is essential to quantify the seismic resilience of urban and rural areas. Various building clusters indicate different damage levels under real earthquakes of different intensities, which directly leads to apparent anomalies in the actual economic losses of various building portfolios. This paper proposes an economic loss assessment model for large-scale regional building portfolios, considering the damage probability matrices. The traditional empirical vulnerability quantification method is optimized and updated by combining the analysis methods of probability risk, reliability, macroseismic intensity, and instrument intensity. Five typical building sample sets (total survey area: 56,937.1893 × 104 m2) of 57 typical cataclysmic earthquakes that occurred in Yunnan Province, China, from 1993 to 2022 are collected and processed, and an updated fragility dataset is established. The calculation model considering empirical structural vulnerability and economic loss quantitative parameters is innovatively developed. Combined with the quantitative approaches of the multidimensional nonlinear fitting model and the established regional empirical structural vulnerability database, the seismic loss evaluation model of large-scale regional structures is established. Ultimately, the earthquake loss point cloud and matrix of typical building portfolios in the large-scale zone are developed using cloud analysis and the proposed seismic loss evaluation model. [ABSTRACT FROM AUTHOR]

Recent earthquakes have highlighted the high vulnerability of the industrial structures that are not specifically designed for accounting seismic forces. Among them, a widespread typology is characterised by steel structures without bracing or other anti-seismic details and with masonry infills. With the aim of increasing the knowledge on the seismic behaviour of these structures, this work focuses on a mechanical-based approach for the evaluation of fragility curves for industrial areas. The exposure data are obtained by in-situ survey and acquiring information available in existing databases, like the Italian Cartis-GL one that is specifically devised for industrial structures. The variability of geometrical and mechanical data and the presence of epistemic uncertainties are considered by constructing a population of structures using the Monte Carlo method. Each structure is analysed through static-nonlinear simulations adopting mixed finite elements accounting for geometrical and constitutive nonlinearities. The approach is tested for infilled steel structures in the industrial area of the municipality of Spezzano Albanese (Italy). Results show that the presence of masonry infill drastically modifies the seismic behaviour of this structural typology. In particular, it turns out that if the mechanical contribution of the infill is neglected, the structures exhibit high damages even for low intensities of the seismic action. [ABSTRACT FROM AUTHOR]

In earthquake-prone countries, transport network managers need to perform extensive seismic risk assessments coping with a considerable number of bridges characterised by an unsatisfying knowledge level and designed in the past without anti-seismic requirements. This study proposes a framework for efficient risk assessment of multi-span girder bridges considering knowledge-based uncertainties. The framework is intended to be applied to risk-informed prioritisation of bridge portfolios. It is based on subsequent modules that involve the input of knowledge data, the simulation of knowledge-based uncertainties, simplified seismic analysis, fragility and loss assessment. The seismic vulnerability of a given bridge is represented by loss ratio percentiles related to a given seismic intensity measure which can be used to quantify the expected annual losses and the corresponding variability due to the influence of knowledge-based uncertainty. A case-study section demonstrates the framework for the widespread category of simply supported girder-reinforced concrete bridges. It addresses issues such as the use of optimal intensity measures, the required number of model realisations and discrepancies with respect to accurate nonlinear time-history analysis. Finally, an illustrative example of the proposed framework for eight case-study bridges in Southern Italy demonstrates its applicability for seismic risk-informed prioritisation of critical bridges and for directing in-depth knowledge data collections where needed. [ABSTRACT FROM AUTHOR]

Due to the unique soil, morphological, and subsurface topographical conditions, amplified and prolonged seismic demand traces were observed in historical strong ground motion records from Bayrakli-Izmir-Turkiye. A vivid example of this response was recorded during the Mw 7.0 Samos event on October 30, 2020. After the event, structural damage and loss of life were unexpectedly concentrated in Bayrakli-Izmir, even though the fault rupture was located 70 km away. The presence of strong ground motion stations (SGMS) located on rock (#3514) and soil (#3513) sites enabled a quantitative assessment of the amplified and prolonged seismic demand traces. The seismic response of SGMS #3513 site was assessed by using 1-D equivalent linear and analytical methods. The idealized 1-D soil profile and input parameters were calibrated and fine-tuned by using the 2020 Samos earthquake accelerograms. Then, the calibrated equivalent linear site response model was further validated by the recordings from historical events. Alternatively, an analytical wave propagation-based model was proposed, the input parameters of which were probabilistically estimated based on, again, historical recordings. Finally, the seismic responses of the site during future earthquakes were predicted based on the calibrated and validated site response models. The predicted intensity-dependent amplification spectral responses were compared with the provisions of the TEC (2018). Even though limited in number in all five future seismic scenario events, amplification ratios suggested by TEC were exceeded by a factor of 2–4 at periods falling in the range of 0.5 to 1.2 s. This clearly suggested the need to further quantify the Bayrakli seismic basin responses with basin-specific models, rather than code-based, intensity-dependent generalized amplification factors. [ABSTRACT FROM AUTHOR]

Industrial facilities, as an essential part of socio-economic systems, are susceptible to disruptions caused by earthquakes. Such disruptions may result from direct structural damage to facilities or their loss of functionality due to impacts on their support facilities and infrastructure systems. Decisions to improve the seismic performance of industrial facilities should ideally be informed by risk (and resilience) analysis, taking into account their loss of functionality and the following recovery under the influence of various sources of uncertainty. Rather than targeting specific individual facilities like a hazardous chemical plant, our objective is to quantify the resilience of interacting industrial facilities (i.e., networked industrial facilities) in the face of uncertain seismic events while accounting for their functional dependencies on infrastructure systems. A specific facility, such as a hazardous chemical plant, can be a compound node in the network representation, interacting with other facilities and their supporting infrastructure components. In this context, a compound node is a complex system in its own right. To this end, this paper proposes a formulation to model the functionality of interacting industrial facilities and infrastructure using a system of coupled differential equations, representing dynamic processes on interdependent networked systems. The equations are subject to uncertain initial conditions and have uncertain coefficients, capturing the effects of uncertainties in earthquake intensity measures, structural damage, and post-disaster recovery process. The paper presents a computationally tractable approach to quantify and propagate various sources of uncertainty through the formulated equations. It also discusses the recovery of damaged industrial facilities and infrastructure components under resource and implementation constraints. The effects of changes in structural properties and networks' connectivity are incorporated into the governing equations to model networks' functionality recovery and quantify their resilience. The paper illustrates the proposed approach for the seismic resilience analysis of a hypothetical but realistic shipping company in the city of Memphis in Tennessee, United States. The example models the effects of dependent water and power infrastructure systems on the functionality disruption and recovery of networked industrial facilities subject to seismic hazards. [ABSTRACT FROM AUTHOR]

Onshore high - pressure gas pipelines constitute critical infrastructure that usually cross seismic - prone regions and are vulnerable to Permanent Ground Deformations (PGDs) due to active seismic faults. In design, it may not be feasible to avoid fault rupture areas due to various technical, economical and topographic reasons. Moreover, the presence of soil layers affects the PGDs resulting from a tectonic fault, which in turn may alter the seismic demand on the pipeline. The current study investigates numerically the impact of soft soil layers on the seismic kinematic distress of onshore gas pipelines. For this purpose, a decoupled numerical modeling approach is adopted, consisting of two separate finite - element models for the simulation of soil response and pipeline distress, respectively. Soil non - linearities are taken into account utilizing the Mohr - Coulomb constitutive model with isotropic strain softening. An extensive parametric analysis is performed considering different faulting mechanisms and fault dip angles, as well as soil geometry and mechanical properties. Consequently, the maximum absolute values of both tensile and compressive pipeline strains are correlated with the seismic intensity level (i.e., in terms of bedrock offset which is associated with earthquake magnitude via simple relationships). The paper concludes with a set of design charts and tables for the preliminary seismic design of onshore high - pressure gas pipelines. These charts and tables predict with reasonable accuracy pipeline deformations, in terms of strains, for different magnitude, fault type, dip angle, sand type, and varying overlying soil layer thickness. [ABSTRACT FROM AUTHOR]

From November to December 2015, shaking table experiments were conducted on a ten-story reinforced-concrete building to acquire useful data for developing advanced technology for seismic structures and to investigate numerical analysis models. Two structural system types, which are a free-standing base-sliding and conventional seismic structure system, were used in this experiment; the second system was the same building as the first, but with a fixed base. The specimen building was subjected to Kobe earthquake motions with amplitudes of 10%, 25%, 50%, 100%, and 60%. The experimental results of the free-standing base-sliding and conventional seismic structures were compared, and regression analysis was conducted on the relationship between the seismic performance of each structure and seismic intensity. During the Kobe earthquake with 100% amplitude, the peak maximum inter-story drift ratio of the free-standing base-sliding was smaller than that of the conventional seismic structure. The acceleration response distributions for the free-standing base-sliding and conventional seismic structure system experiments with smaller amplitudes were similar to the distribution provided by the Architectural Institute of Japan. The shear force coefficient at the base-sliding surface did not fluctuate significantly, despite the increase in sliding velocity. According to the regression analysis results, the global rotation stiffness ratio and equivalent story stiffness ratio of each story may be related to the cumulative value of the peak velocity of the shaking table; further, the peak maximum inter-story drift ratio may be linearly related to the seismic intensity. [ABSTRACT FROM AUTHOR]

Two models of the 10-story reinforced concrete building tested at E-Defense laboratory in 2015 are built: the F model, in which nonlinear behavior is distributed over the element length, and the H model, in which nonlinear behavior is lumped in plastic hinges with a moment-chord rotation response assigned based on empirical formulations proposed in the literature. Nonlinear time–history analyses are performed to reproduce the experimental shaking-table tests performed at increasing seismic intensity level. The incremental experimental test has been performed twice: the first time (BS test), the structure base was free to slip on a concrete base fixed to the shaking table. After the BS test, a second test was performed on the same structure with the foundation fixed to the concrete base (BF test). Both tests are simulated for both models. When simulating both the BS and BF tests, the seismic input adopted for the numerical analyses is the displacement time-history registered at the base of the specimen's columns, in order to implicitly account for base slip through the input signal without explicitly modeling the slipping devices. It is observed that the significant damage experienced by the specimen during the runs of BF tests at medium–high seismic intensity is probably triggered by softening and damage of beam-column joints: this is reproduced also by H numerical model and highlights the influence of beam-column joints on the overall seismic response of the structure. In general, it is observed that both numerical models, which were constructed, based on experimental data, only by adopting available and well-established tools proposed in the literature, can reproduce the overall response of the case-study structure, especially in terms of maximum top displacement demand and maximum damage state for structural members, provided that beam-column joints' contribution is adequately considered. [ABSTRACT FROM AUTHOR]

This study is aligned with United Nations, Sustainable Development Goal 11, concerned about making cities and human settlements inclusive, safe, resilient and sustainable, in particular, in line with resilience to disasters, and protecting the world's cultural heritage targets. Focused on a small sample of rammed earth residential dwellings in the city of Mula, one of the areas of highest seismic hazard in Spain, the seismic vulnerability has been assessed adapting the Vulnerability Index Method (Risk-UE) to tackle the specificities of earthen residential buildings. The majority of this humble earthen heritage, despite being an essential part of the Spanish Culture, suffers from the effects of abandonment and insufficient maintenance. As a consequence, these genuine buildings will be seriously damaged in the event of an earthquake of intensities from VII to VIII, with heritage losses representing 17% to 43% of the built area. These research outcomes can be used to define repair and strengthening priorities among the buildings in the sample when financial resources are limited. The proposed indices and coefficients can be applied to similar earthen structures, widely built in the Iberian Peninsula and the Mediterranean region. [ABSTRACT FROM AUTHOR]

The spatial estimation of the soil response is one of the key ingredients for the modelling of earthquake risk. We present a ground motion amplification model for Switzerland, developed as part of a national-scale earthquake risk model. The amplification model is based on local estimates of soil response derived for about 240 instrumented sites in Switzerland using regional seismicity data by means of empirical spectral modelling techniques. These local measures are then correlated to continuous layers of topographic and geological soil condition indicators (multi-scale topographic slopes, a lithological classification of the soil, a national geological model of bedrock depth) and finally mapped at the national scale resorting to regression kriging as geostatistical interpolation technique. The obtained model includes amplification maps for PGV (peak ground velocity), PSA (pseudo-spectral acceleration) at periods of 1.0, 0.6 and 0.3 s; the modelled amplification represents the linear soil response, relative to a reference rock profile with VS30 (time-averaged shear-wave velocity in the uppermost 30 m of soil column) = 1105 m/s. Each of these amplification maps is accompanied by two layers quantifying its site-to-site and single-site, within event variabilities, respectively (epistemic and aleatory uncertainties). The PGV, PSA(1.0 s) and PSA(0.3 s) maps are additionally translated to macroseismic intensity aggravation layers. The national-scale amplification model is validated by comparing it with empirical measurements of soil response at stations not included in the calibration dataset, with existing city-scale amplification models and with macroseismic intensity observations from historical earthquakes. The model is also included in the Swiss ShakeMap workflow. [ABSTRACT FROM AUTHOR]

Near-fault earthquakes can cause more intricate dynamic responses and potentially lead to severe damage to bridge structures compared to far-field earthquakes. In January 8, 2022, a 6.9-magnitude earthquake struck Menyuan, Qinghai Province, resulting in the disruption of the Lanzhou-Urumqi high-speed railway. The Liuhuanggou Bridge is the first high-speed railway bridge in the world to have undergone severe earthquake damage. In order to investigate the reasons for the seismic damage and girder falling mechanism, this study established a comprehensive nonlinear analysis model that considers the entire process from mild damage to complete failure of bridge components. Based on the LS-DYNA explicit dynamic analysis software, the model accurately simulates the collision, girder falling, and bearing damage. Based on limited field investigation data and combined with theoretical methods, reasonable seismic inputs are constructed, which accurately reproduce the bridge damage. The analysis results indicate that the girders and piers of high-speed railway simply supported bridges exhibit good seismic performance under seismic, while the bearings and shear keys are damaged. The seismic intensity (IX degree) significantly exceeded the fortification intensity (VII degree) of the bridge. The near-fault earthquake velocity pulse, inappropriate seismic measures, and nonuniform excitation of cross-fault earthquake are significant factors leading to the collapse of the Liuhuanggou Bridge. Further research is needed for the rational selection of bridge types in fault zones. The numerical results and conclusions of this study can provide a reference for the seismic design of high-speed railway simply supported bridges built near faults. [ABSTRACT FROM AUTHOR]

The determination of ground motion is crucial to plan the appropriate emergency activities, especially in areas characterised by an intense seismic history like the Italian peninsula. Ground motion assessment is generally based on the seismological parameters reported in the instrumental and parametric seismic catalogues. Therefore, the computation of shaking scenarios of historical earthquakes is very challenging, due to the poorly constrained variables (i.e., magnitudes, epicentral location, seismogenic sources), derived from the macroseismic intensity. In this study, we propose a novel approach to investigate the location and parametrization of the seismogenic sources of historical earthquakes and derive shaking scenarios. To this aim, the ground motion of two historical events, the Fabriano (1741, Mw = 6.1, Imax IX MCS) and Camerino (1799, Mw = 6.1, Imax IX–X MCS) earthquakes is simulated. In order to include the site response, a Vs,30 map of the Umbria and Marche regions is created from near-surface data. Different causative faults solutions are tested, finally discussing the ideal seismogenic source based on the residual analysis between observed and simulated macroseismic intensities. The resultant shaking scenarios of the two events are obtained by integrating observed intensities and simulations. [ABSTRACT FROM AUTHOR]

In this paper, we tackle the problem of the intensity attenuation at Ischia, a critical parameter in a high seismic risk area such as this volcanic island. Starting from the new revised catalogue of local earthquakes, we select a dataset of 118 macroseismic observations related to the four main historical events and analyse the characteristics of the intensity attenuation according to both the deterministic and probabilistic approaches, under the assumption of a point seismic source and isotropic decay (circular spreading). In the deterministic analysis, we derive the attenuation law through an empirical model fitting the average values of ΔI (the difference between epicentral intensity I0 and intensities observed at a site IS) versus the epicentral distances by the least-square method. In the probabilistic approach, the distribution of IS conditioned on the epicentre-site distance is given through a binomial-beta model for each class of I0. In the Bayesian framework, the model parameter p is considered as a random variable to which we assign a Beta probability distribution on the basis of our prior belief derived from investigations on the attenuation in Italy. The mode of the binomial distribution is taken as the intensity expected at that site (Iexp). The entire calculation procedure has been implemented in a python plugin for QGIS® software that, given location and I0 (or magnitude) of the earthquake to be simulated, generates a probabilistic seismic scenario according to the deterministic or probabilistic models of attenuation. This tool may be applied in seismic risk analyses at a local scale or in the seismic surveillance to produce real-time intensity shake-maps for this volcanic area. [ABSTRACT FROM AUTHOR]

This paper investigates the seismic performance of an RC frame subjected to horizontal ground motions and vertical ground motions (VGMs) through the application of a shaking table test of a two-story, 1/2-scale three-dimensional (X-, Y- and Z-axes) reinforced concrete (RC) frame. The horizontal ground motions and VGMs are input along the X- and Z-axes of the specimen, respectively. The structural responses monitored in the test include the specimen's dynamic properties, displacements, and accelerations. The test results support the following findings: (1) the beams of the frame are heavily damaged due to the vertical load caused by the VGM. The damages to the beams on the second floor are more severe than those on the first floor because the vertical loads of the second story caused by VGMs are larger than those of the first story. (2) The vertical acceleration amplification factor of the slab in the first (second) story generally decreases from 3.54 to 2.93 (2.3–1.93) as the seismic intensity increases. (3) The horizontal frequency (X-axis) after the test is reduced to approximately 40% of the elastic frequency of the structure before the test. The vertical frequency (Z-axis) is reduced to approximately 65% of that of the undamaged structure. The horizontal frequency (Y-axis) after the test is also reduced to approximately 56% of the elastic frequency of the structure, although no seismic excitations are input along the Y-axis. [ABSTRACT FROM AUTHOR]

The concept of macroseismic intensity arose with the purpose of measuring the strength of an earthquake by the effects it causes on buildings, people, and domestic furnishings. From this perspective, buildings can be considered seismic sensors that record the shaking. Early scales were conceived at a time when buildings were mainly in masonry and therefore they could be used as markers of the intensity in case of earthquakes. Indeed, since they were fairly homogeneous, their level of damage could be considered as an indicator of the shaking level. In recent decades, the evolution of construction techniques have made the MCS scale unsuitable for damage assessment of buildings of various resistance. To overcome this problem the EMS-98 scale was designed. Because the MCS scale is still used in Italy, even in the presence of many reinforced concrete buildings, the purpose of this work is to show that the EMS-98 is the most suitable tool for assessing intensity as it is more consistent with the built environment. Theoretical and real intensity assessments, by both MCS and EMS-98, have been determined and compared, showing that nowadays intensity is a function of the vulnerability. MCS and EMS-98 would be comparable only when the building stock is composed of very vulnerable edifices (generally class A). Finally, thanks to the similarity of the two scales for old and vulnerable buildings, EMS-98 appears fully adequate to investigate historical earthquakes and represents a powerful tool to ensure continuity among earthquakes of different epochs. [ABSTRACT FROM AUTHOR]

The modern engineering approach to design of structures exposed to rare but intense earthquakes allows for their inelastic response. Models and tools to rapidly but accurately assess the extent of the inelastic response of the structure and control its performance are, therefore, essential. We develop a closed-form μ - R ∗ - S d , y relation between the ductility μ and the strength reduction factor R*, as well as its approximate inverse R*- μ -Sd,y relation, both functions of the SDOF oscillator yield displacement Sd,y, not its vibration period T. The fundamental vibration period of the structure varies during the iterative design process focused on modifying its strength. However, the yield displacement of the structure is practically invariant with respect to the strength of the structure, as it depends primarily on its geometry and material properties. We use these relations to formulate a constant yield displacement seismic design procedure and exemplify it. Noting the structure of the developed relations, we use dimensional analysis to formulate a version of the ductility-strength and strength-ductility relations that are dimensionless and independent of the seismic hazard intensity. These novel, dimensionless master relations are the μ -R*-H/B- κ ductility-strength and the R*- μ -H/B- κ strength-ductility relations. [ABSTRACT FROM AUTHOR]

Construction sites are not generally flat but heterogeneous. It would be of significance to explore the patterns of ground response where soil and rock strata laterally distribute near the ground surface. Shaking table test of scaled free-field model is conducted to investigate the local site effect caused by the influence of soil-rock strata. In this test, model ground with artificial soil and rock is designed to reproduce the dynamic characteristics of the prototype. Recorded earthquake waves and site-specific artificial waves are selected as the bedrock motions inputted from the shaking table, in both transverse (SH wave) and longitudinal (SV wave) directions. Four sites of the ground are classified according to the combination of the soil deposit and the rock. The standard spectral ratio (SSR) is introduced to identify the fundamental frequency and the amplification amplitude of the four sites. Correspondingly, one-dimension (1D) theoretical analysis is used to clarify the amplification effects affected by the local constitution at each local site of the ground by comparing the response spectral ratios with the 1D analysis results (Aggravation factor). Site-specific parameters, such as the peak ground acceleration, arias intensity, and acceleration response spectra, are documented with discussions. It is found that the amplifications of locations vary with thickness of soil deposit, nonlinearity of soil property under increasing seismic intensity, and scattering of high-frequency components of input motion. [ABSTRACT FROM AUTHOR]

UnReinforced Masonry (URM) buildings constitute the majority of the Italian building stock and represent one of the most vulnerable construction typologies, as emerged during the seismic events occurred in the last decades. The objective of the present work is the proposal of a methodology for the seismic vulnerability and fragility assessment of different typologies of URM buildings. Through the statistical analysis of post-earthquake damage survey forms and of census data, the most prevalent structural typologies were identified in the Emilia Romagna region (Italy), leading to the definition of two reference masonry buildings, built at the beginning of the XX century and representative of the building stock of the study area. These buildings were modeled according to the equivalent frame method and their seismic performance was studied by means of nonlinear static analyses, considering uncertainties on the mechanical properties of masonry, on the intensity of the seismic action and on the displacement demand calculation method. Through the definition of Response Surfaces, analytical fragility curves relative to the investigated structural typologies were determined for the different damage states. [ABSTRACT FROM AUTHOR]

The severe socio-economic impact of recent earthquakes has represented a tough reality check, further confirming the mismatch between society expectations and reality of seismic performance of modern buildings. Life-safety code-compliant design criteria are not enough when dealing with new structures. To raise the bar in terms of structural safety and overall performance objectives, the renewed challenge is defining high-performance buildings able to sustain a design-level earthquake with minimum disruption of business and limited economic losses. To achieve this goal, alternative strategies might be adopted: (a) implementing more advanced design methodologies, (b) increasing the seismic design level, (c) adopting low-damage earthquake-resistant technologies. However, the common perception is that these strategies would lead to unaffordable costs. To support decision-makers, the paper develops a comprehensive parametric study to compare the cost–benefit of reinforced concrete multi-storey buildings designed for increasing levels of seismic intensities (representing a higher seismicity zone or Importance Class) and according to alternative design approaches (Force-based vs. Displacement-based) and technologies (traditional vs. low-damage). Analytical/numerical investigations are carried out to determine the building performance, and loss assessment analyses are performed to compute the Expected Annual Losses of all the parametric configurations. Results, further elaborated through a machine-learning technique, highlight the convenience of implementing more advanced design methodologies, such as a displacement-based approach allowing for a better control of the building response, and the remarkable benefits of applying low-damage technologies, leading to a very high performance and significantly reduced economic losses (> 50%) for a small increase (< 5–10%) of the initial investment cost. [ABSTRACT FROM AUTHOR]

By integrating the vulnerability index of buildings, earthquake disaster matrix, and historical earthquake disaster data, the vulnerability of typical buildings and compounds in rural areas of China are analyzed. The disaster matrix of buildings in historical earthquakes was obtained by analyzing historical earthquake disaster data. By integrating the historical disaster matrix and vulnerability analysis of typical structures in rural areas, a seismic disaster matrix was established to assess the seismic performance of regional compounds. Combined with the historical earthquake disaster matrix and vulnerability index, the lognormal distribution function was used to analyze the vulnerability index of regional structures and compounds to obtain the disaster matrix of structures under different seismic intensities. Considering the structures and compounds in the rural areas in the Tianjin district as an example, the seismic vulnerability of typical structures was investigated. The regional structure disaster matrix of the study region was established and the vulnerability indices of different types of structures and compounds were obtained to clarify the regional disaster prevention ability. [ABSTRACT FROM AUTHOR]

Evaluating the seismic vulnerability of regional group structures is essential for effectively quantifying the seismic resilience and risk analysis of regional cities. To study the degree of damage caused by a typical earthquake to the overall group of buildings in a specific area, this paper takes the field observation data of the Wenchuan earthquake on May 12, 2008, in China as the research background and makes empirical vulnerability statistics and classification on all the inspection data of structural groups in Dujiangyan city. The seismic risk experience database (8621 building samples) based on the overall regional group buildings is developed. Using nonlinear regression, probabilistic risk prediction, and a cumulative damage conditional probability model, the empirical vulnerability matrices of six typical groups of buildings in different seismic intensity zones are established. Considering the effects of seismic design, age, purpose, number of floors, and plane shape features on the seismic resilience and vulnerability of regional group structures, a multifactor vulnerability innovation comparison model based on updating the quantitative scale of vulnerability level is developed. Ultimately, an innovative seismic vulnerability update index domain assessment model is proposed to quantify the damage modes of regional group structures. Zonal fragility prediction models of six typical regional structure groups are established. In the analysis results of the multidimensional empirical vulnerability model, it is found that with the increase in the macroseismic intensity grade, the sample number distribution shows a decreasing trend. Additionally, an essential finding is that the damage of the regional reinforced concrete structure is relatively light, indicating that it has a certain seismic resilience. The empirical vulnerability database is used within the proposed model to obtain a seismic vulnerability index. [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]

The importance of non-structural elements on the seismic performance of buildings is now widely recognized. A building cannot achieve a life-safety or continuous functionality performance after an earthquake if all its non-structural elements are damaged and/or out of function. Suspended non-structural elements, such as piping and mechanical services, play a crucial role in maintaining life-safety and functionality of a building after an earthquake. The importance of non-structural elements for the seismic performance of buildings have prompted the development of both force-based and displacement-based seismic design methodologies that can be applied to suspended non-structural elements. This paper focuses on appraising force-based and displacement-based seismic design methodologies available in Europe for suspended non-structural elements by comparing fragility functions for a case-study suspended piping trapeze restraint installation layout located in a mid-to-high seismic zone in Italy. The aim of this study is to determine if the seismic design methodologies available for suspended non-structural elements are capable of producing archetypes that achieve a life-safety performance objective for a design level earthquake (return period of 475 years) and maintain a reasonable performance, in terms of life-safety, for other earthquake intensity levels. Advantages and disadvantages of these methodologies are also highlighted. [ABSTRACT FROM AUTHOR]

We present a dataset of 77 strong ground motion records within 200 km epicentral distance from the 30 October 2020, M7.0 Samos Island (Aegean Sea) earthquake, which affected Greece and Turkey. Accelerograms from National Networks of both countries have been merged into a single dataset, including metadata that have been uniformly derived using a common preliminary source model. Initial findings from the analysis and comparative examination of acceleration time histories, Fourier amplitude spectra and 5%-damped response spectra are discussed along with significant source, propagation path and site effects. The long-period amplifications observed in most records in Izmir bay triggered failures and severe damages in weak structures. Yet, the spectral accelerations are observed to lie below the current and previous design spectra corresponding to the damaged regions. Peak ground motions are used to construct a purely instrumental-based macroseismic intensity map, which is capable of reflecting the actual earthquake damage caused by this considerably large event. Finally, peak ground motions are compared to various ground motion models (GMMs) and deviations are highlighted. Our overall preliminary analysis reveals a strong energy signature of the Samos earthquake in the period range 0.5–1.5 s at many sites, both on rock and soil, whereas records in the heavily hit Izmir city, at an epicentral distance circa 70 km, provide strong indication for additional amplification due to basin effects. At relatively large distance from the earthquake source (> 120 km), several recorded amplitudes are significantly lower than those predicted by many GMMs, implying that further studies are necessary toward the improvement of regional attenuation models. [ABSTRACT FROM AUTHOR]

Given the increase of nuclear power plants, it has become unavoidable for the pile-supported nuclear-island buildings to be constructed on the coastal deposits potentially influenced by strong earthquakes. The coupling influences of the hysteresis nonlinearity of soil and the soil-pile-structure interaction (SPSI) have not yet been considered comprehensively in the seismic response analysis of the nuclear-island building, although it is a vital issue. On the basis of a newly-developed generalized non-Masing hysteretic constitutive model, a 3D integrated simulation method is proposed to evaluate the seismic responses of the pile-mat-founded nuclear-island building system subjected to multidirectional earthquake motions. This integrated method involves an explicit parallel algorithm framework, comprising the nuclear-island building modeling, the pile-mat foundation modeling, the inhomogeneous soil domain modeling, and the artificial boundary condition. The bedrock records of near-field, moderate-far field and far-field earthquake scenarios are assumed for determining the bedrock motions of the ultimate and operational safety earthquakes. For an actual pile-mat-founded AP1000 nuclear-island building, the simulation results show the complexity and significance of the coupling effect of the site, the tridirectional earthquake shaking, and the secondary nonlinearity of soil. Such a complex coupling effect significantly increases the seismic responses of the pile-mat-founded nuclear-island building. A notable finding is that the scenario earthquakes with abundant long period components may have more destructive potential to the pile-mat-founded nuclear-island buildings than the scenario earthquakes with characteristics of abundant short period components and shorter durations. The results provide insights into the seismic design of the pile-mat-founded nuclear-island buildings, which could guide the design and construction of such similar facilities in the high seismic intensity regions. [ABSTRACT FROM AUTHOR]

Seismic-resistant self-centering concentrically braced frames (SC-CBFs) are susceptible to the concentration of inter-story drifts during earthquakes owing to the relatively low energy dissipation ability of braces. To address this limitation, this study proposed a novel solution by designing a strong backup (SB) system to mitigate inter-story deformation concentration in “weak” stories. The proposed SB system consisting of truss members can be attached to the existing SC-CBF through pin connections, forming a system, termed strong backup SC-CBF (SC-CBF-SB), to promote a more uniform distribution of inter-story drifts along the height of the frame and mitigate the weak story behavior. A six-story chevron-braced frame is adopted to investigate the seismic performance of SC-CBF and SC-CBF-SB. Finite element models of SC-CBF and SC-CBF-SB are built. The mechanical characteristics and dynamic responses of the SC-CBF-SB are examined. To comprehensively evaluate the performance of both SC-CBF and SC-CBF-SB, static pushover analyses and nonlinear time-history analyses are conducted. Additionally, incremental dynamic analysis (IDA) is performed to evaluate the responses (particularly drift concentration) of both frame types subjected to increasing seismic intensity levels. Numerical results show that the maximum value of the drift concentration factor (DCF) is around 1.3 and 1.8 for SC-CBF-SB and SC-CBF, respectively, indicating that SC-CBF-SB can effectively mitigate inter-story drift concentration of SC-CBF. Meanwhile, the proposed SB system has a minimal negative impact on the favorable SC ability of the frame. [ABSTRACT FROM AUTHOR]

A Ground Motion Intensity Measure (GMIM) provides a quantitative metric of the strength of a ground motion with the objective of defining a mapping to the damaging effects induced by earthquakes. The correlation between GMIMs and earthquake damage allows their use in earthquake engineering applications such as (pre-event) seismic hazard/risk assessment and mitigation, and (post-event) damage assessment and resource allocation for disaster response. GMIMs are also used for damage prediction in the context of performance-based earthquake engineering and earthquake-resistant design. This paper presents the evaluation of GMIMs using strong motion records obtained during the 2023 Turkey-Syria earthquake. The GMIMs studied include peak ground acceleration, peak ground velocity, spectral accelerations, root-mean-square acceleration, Arias intensity, cumulative absolute velocity, Housner spectral intensity, and Araya-Saragoni intensity. The GMIMs are evaluated at several spatial locations where ground motion records were measured during the events. The results demonstrate that some GMIMs showed significantly high values at locations where severe damage was observed after the earthquake. Based on a cross-correlation analysis the peak ground acceleration and the root-mean-square acceleration were the GMIMs that showed the strongest correlation with the observed damage. It is also shown that the maximum considered earthquake spectra were exceeded at several locations where extensive damage was observed, with the design base shear underestimated by a factor of up to four when considering the compounding effects of the strong ground motion shaking and the fundamental vibration period shift due to the stiffening induced by infill walls in frame structures. [ABSTRACT FROM AUTHOR]

An efficient design method should provide practitioners with a means for sizing timber buildings to meet specific performance levels against estimated earthquake intensities. Displacement and energy design considerations in force-based design (FBD) procedures are not as precise as intended in complex systems, such as mid- to high-rise timber buildings. The main aim of this study is to tailor the direct displacement-based design (D-DBD) classical framework to platform-type cross-laminated timber (CLT) shear wall structural systems and validate their performance for low-rise to high-rise timber mixed-use buildings. A comparison with results obtained via the FBD analyses is also provided. To this end, timber buildings with heights of 4, 8 and 12 stories are designed via the D-DBD and FBD methods. The seismic performance of platform-type CLT wall buildings is assessed in terms of the repair cost, repair time and casualty rate using FEMA P-58 methodology. The seismic response of CLT shear walls shows that the FBD method may lead to an expensive overdesign, especially in high-rise platform-type CLT walls. Conversely, the D-DBD method develops structural systems which can sustain a comparable level of damage from low- to high-rise platform-type CLT walls. Although the seismic loss assessment of buildings shows slightly better performance for the FBD method than the D-DBD method, it is worth noting that the D-DBD method does not lead to an unsafe building. Consequently, the D-DBD method sounds like a proper alternative approach for designing the CLT shear walls to achieve target performance levels without requiring a premium upfront cost. [ABSTRACT FROM AUTHOR]

In recent years, precast segmental bridge columns (PSBCs) have been widely used in high-speed railway bridges, but the lack of long-term seismic performance limits PSBCs application in harsh environments and high-intensity areas. However, the selection of high-speed rail lines in high-intensity offshore areas is inevitable. Therefore, considering the impact of environmental erosion and earthquake, it is necessary to study the seismic performance of PSBC. In order to study the application of PSBCs in offshore high-intensity areas, this paper comprehensively compares the time-varying seismic fragility of PSBCs and cast-in-place bridge columns (CPBCs) in high-speed railway bridges. Based on offshore high-speed railway columns, the finite element models of representative PSBCs and CPBCs are established and verified by experiments. Then, the verified finite models are utilized to implement the time-varying fragility analysis by considering chloride ion erosion under four damage states. The main conclusions are as follows: the exceeding probabilities of PSBCs and CPBCs are close in intact bridges under different damage states and seismic intensities. With the prolongation of bridge service time, the steel bars corrosion rate of PSBCs is faster than that of CPBCs due to the discontinuity of PSBCs segments, the exceeding probabilities of PSBCs increase more rapidly than those of CPBCs. When the columns reach the design working life, the exceeding probability and PGA (Peak Ground Acceleration) median of PSBCs are higher than those of CPBCs under four damage states. Taking the moderate damage state as an example, the maximum exceeding probability of PSBCs and CPBCs were 97.2% and 89.1%, respectively, and the PGA median of PSBCs were 24% lower than that of CPBCs at 100 years. This work provides a theoretical foundation for the better application of PSBCs in offshore high-intensity areas. [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]

This paper contains a large-scale seismic assessment of the downtown area of Skikda city in Algeria. This area was identified for the present work based on its importance regarding size and the legacy of older buildings for which information was available. Moreover, seismic microzonation studies for the city of Skikda based on the simulation of local effects are available. This paper aims to evaluate the seismic risk in the old part of Skikda using the Risk-UE LM1 methodology, namely, the empirical method LM1 based on an in situ survey. Damage probability matrices have been obtained for the deterministic (historical events) and probabilistic earthquake scenarios (i.e., characterized by a return period), in accordance with the city's microzoning study. The results of the seismic risk assessment in the city are represented by damage to buildings. Thus, physical damage was also used as a hazard-related variable to predict economic and human losses, and other quantities, such as restoration cost and quantities of debris, were studied. Despite the moderate seismic risk in Skikda, the results show a high risk due to the high exposure and vulnerability of the buildings, which are generally made up of buildings in unreinforced masonry. Important social and economic losses are expected in these areas as well. The seismic risk of Skikda was estimated as moderate with a predicted number of 83 million USD global economic impacts, including economic losses and restoration costs for a seismic intensity scenario of VII. To better manage and analyze the human and economic exposure. The seismic risk maps was elaborated to be used as a guide to decision-making to prepare emergency plans for earthquake risk mitigation in Skikda. [ABSTRACT FROM AUTHOR]

Seismic loss prediction of regional-scale buildings provides key information for disaster management. However, previous seismic loss prediction models ignored the time-lag effect of cost information and adopted rough loss ratios without considering the characteristics of a region and disaster (including GDP, magnitude, focal depth, epicentre intensity, seismic precautionary intensity, and design basic acceleration of ground motion), which prevented the earthquake loss prediction from achieving sufficient forecasting accuracy. This study develops a novel storey-based seismic direct loss prediction model of regional-scale buildings for the pre-earthquake hazard mitigation and post-earthquake disaster responses based on the machine learning approach. Specifically, the multi-factor support vector machine (SVM) model is established to predict loss ratios, and the hybrid model (ARIMA-SVM) composed of the autoregressive integrated moving average (ARIMA) model and SVM is built to forecast unit replacement costs. The results show that the above models can achieve promising forecasting performance. Finally, the prediction framework has been applied to Wangjiang Campus of Sichuan University in China, and the spatial distribution of storey-level seismic damage and losses in this region can be visualized. Importantly, the outcome of this study provides a comprehensive and realistic understanding of future losses in a region, which supports decision makings in disaster mitigation. [ABSTRACT FROM AUTHOR]

The probability of light damage to unprepared, unreinforced masonry structures exposed to induced seismicity due to gas extraction in the north of the Netherlands is still under investigation. Repeated light seismic excitations caused by frequent, light and nearby earthquakes have been linked to economical losses and societal unrest in particular, with extensive damage claims. Moreover, the damaging potential of the seismic events has been related to the condition of the structure, especially if damage corresponding to settlement causes is already present. A comprehensive testing campaign oriented towards the initiation and progression of light damage of replicated clay brick masonry has been conducted at Delft University of Technology. Based on these tests, calibrated finite element models have been produced. This article uses the calibrated non-linear time-history models to simulate the effect of earthquake ground motion on a variety of initial conditions, wall geometry, material properties, and number, type and intensity of earthquakes. The results are then used to regress a relationship between damage and these parameters. This is subsequently employed to run a MonteCarlo simulation and produce fragility curves where the probability of exceeding specific damage values for various initial damage levels is presented against the seismic hazard. The vulnerability or fragility curves show that visible damage, with cracks wider than 0.1 mm, appears, with a 10% exceedance probability, at 13 mm/s of peak ground velocity; but, if the masonry had already undergone some light, yet imperceptible damage, a PGV of 6 mm/s was sufficient to aggravate it into visible cracks. To attain a 1% probability of exceeding light damage however, for which the masonry would need more invasive repair, it was observed that PGVs larger than 15 mm/s were required. These fragility curves were finally compared to graphs from other authors and found to capture well the variability in the range assigned to light damage. [ABSTRACT FROM AUTHOR]

To deeply explore the seismic vulnerability characteristics of typical structures and obtain the differences in the seismic capacity of multiple structural categories in actual earthquakes, combined with mathematical statistics and probabilistic damage model analysis methods, the bulk of collection and statistics were made on the structural seismic damage observation data (98,051.8122 × 104 m2 and 995,269 buildings) of 213 destructive earthquakes in China from 1975 to 2013. Seismic damage sample databases of wooden roof truss structures, adobe and timber structures, brick wood structures, masonry structures, RC structures, and bottom frame seismic wall masonry structure were established. A seismic damage investigation and analysis were conducted. All samples' vulnerability grades were evaluated using the latest version of the Chinese seismic intensity scale (CSIS-20). The actual damage vulnerability probability matrix and surface model of structures in multiple intensity regions based on the investigated area and quantity parameters were established. A nonlinear regression prediction model analysis method was proposed. A typical structural vulnerability prediction model considering the failure ratio and exceedance probability in the multi-intensity region was established and verified by the earthquake damage database. In addition, a vulnerability matrix prediction model considering updating the mean vulnerability index parameter was proposed, and a comparison model of the vulnerability prediction matrix of typical regional structures was developed. [ABSTRACT FROM AUTHOR]

Rocking wall structures present a resilient alternative to conventional structures. Although the displacement responses of these structures have been discussed in past works, the force-based responses especially in the context of nonlinearity due to gap-opening behavior need to be explored in detail. In the current research, the effect of gap-opening behavior at predetermined locations in the rocking walls on the seismic force responses has been discussed. For this purpose, five rocking walls of varying heights and against two levels of seismic intensity are designed and analyzed using time history analysis procedure. A modal decomposition technique is used to separate the complex responses to their modal responses to better understand the different factors in play. It is found that the modal properties based on initial stiffness properties are unable to predict the inelastic seismic demands and a new capacity design procedure, based on modified modal properties incorporating the effect of gap-opening, has been proposed. The issues associated with the use of modified modal properties are discussed in detail and a simple, yet effective solution is shown to provide a much better prediction of inelastic seismic responses of these structures. [ABSTRACT FROM AUTHOR]

Seismic hazard maps from probabilistic seismic hazard analysis or PSHA collect, at different sites, the values of the (site-specific) ground motion intensity measures of interest that, taken individually, have the same exceedance return period. For large-scale analyses, a widely used intensity measure is the macroseismic (MS) intensity, that provides an assessment of the earthquake effect based on the observed consequences in the hit area. Hazard maps can be developed in terms of MS intensity, and some examples exist in this respect. In the case of Italy, the last MS hazard map is based on the same seismic source model (known as MPS04) adopted to derive the design seismic actions of the current building code, a study dating more than ten years ago. It provides results in terms of countrywide Mercalli–Cancani–Sieberg (MCS) intensity level with 475 years return period. This short paper presents and discusses MCS probabilistic seismic hazard maps for Italy based on a recent grid-seismicity source model, herein named MPS19, synthetizing the large effort of a wide scientific community. The results, which are obtained by means of classical PSHA, are given in the form of maps referring to the 475 years return period, and also others of earthquake engineering interest. Moreover, it is discussed that the return period does not univocally identifies the MS intensity because, although MS is, by definition, a discrete random variable, it is modelled, in a given earthquake, by means of a normal distribution, that is, treated as continuous. Thus, the maps of the minimum return period causing the occurrence or exceedance of different MCS intensities are also provided. Finally, the comparison between the 475 years return period hazard map presented and the one which is currently the point of reference in Italy, that is, computed using MPS04, is briefly discussed. All the computed maps are made available to the reader as supplemental material. [ABSTRACT FROM AUTHOR]

This paper focuses on the probabilistic analysis of Intensity Measures (IMs) and Engineering Demand Parameters (EDPs) in the context of earthquake-induced ground motions. Several statistical properties, which are desirable in IMs when they are used to predict EDPs, have been analysed. Specifically, efficiency, sufficiency and steadfastness have been quantified for a set of IMs with respect to two EDPs: the maximum inter-storey drift ratio, MIDR, and the maximum floor acceleration, MFA. Steadfastness is a new statistical property proposed in this article, which is related to the ability of IMs to forecast EDPs for large building suites. In other words, this means that efficiency does not significantly vary when different types of buildings are simultanously considered in the statistical analyses. This property allows reducing the number of calculations when performing seismic risk estimations at urban level since, for instance, a large variety of fragility curves, representing specific building typologies, can be grouped together within a more generic one. The main sources of uncertainty involved in the calculation of the seismic risk have been considered in the analysis. To do so, the nonlinear dynamic responses of probabilistic multi-degree-of-freedom building models, subjected to a large data set of ground motion records, have been calculated. These models have been generated to simulate the dynamic behavior of reinforced concrete buildings whose number of stories vary from 3 to 13. 18 spectrum-, energy- and direct-accelerogram-based IMs have been considered herein. Then, from clouds of IM-EDP points, efficiency, sufficiency and steadfastness have been quantified. For MIDR, results show that IMs based on spectral velocity are more efficient and steadfast than the ones based on spectral acceleration; spectral velocity averaged in a range of periods, AvSv, has shown to be the most efficient IM with an adequate level of steadfastness. For MFA, spectral acceleration-based-IMs are more efficient than velocity-based ones. A comparison is also presented on the use of linear vs quadratic regression models, and their implications on the derivation of fragility functions. Concerning sufficiency, most of the 18 IMs analysed do not have this property. Nonetheless, multi-regression models have been employed to address this lack of sufficiency allowing to obtain a so-called 'ideal' IM. [ABSTRACT FROM AUTHOR]