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The Taiwan Ground Deformation Index (TGDI) is proposed to quantify site vulnerability using a non-linear soil deformation model, PGA parameters from the Taiwan seismic intensity scale, and microtremor analysis. Site vulnerability is graded into four levels: low (TGDI < 2.4), moderate (2.4 ≤ TGDI < 4.2), high (4.2 ≤ TGDI < 7.4), and very high (TGDI ≥ 7.4), based on susceptibility to seismic damage. Validating TGDI with 13 disaster events in Tainan during the 2016 Meinong earthquake showed 12 cases of moderate-to-high vulnerability. Since weak ground and strong amplification properties favor TGDI increases, this index serves as an early warning parameter for disasters. [ABSTRACT FROM AUTHOR]

In-service reinforced concrete (RC) structures trigger complex deterioration mechanisms in seismic performance due to corrosion, leading to difficulties in evaluating the seismic capacity. To scientifically evaluate the seismic capacity of corroded RC frame structures, this paper proposes a quantifiable framework for absolute seismic capacity evaluation. The study establishes numerical models of typical RC frame structures considering the number of stories, service years, seismic fortification intensity, and different versions of design codes. Additionally, classification criteria for structural failure states based on the proportion of component damage are proposed. The seismic capacity of corroded RC frame structures under different failure states is determined using elastoplastic time-history analysis, and the influence of various parameters on the structural seismic capacity is investigated. Based on the results of the structural seismic capacity evaluation, a prediction model for the seismic capacity of corroded RC frame structures is developed using the BP neural network to establish the nonlinear mapping relationship between key parameters and structural seismic capacity. The results indicate that the seismic capacity of corroded RC frame structures continuously decreases with an increase in the service years and the number of stories. Earlier versions of design codes result in smaller residual seismic capacity of RC frame structures under different failure states, with a faster degradation rate. The sensitivity of the structural seismic capacity to various parameters is ranked as follows: structural failure states, the number of stories, seismic fortification intensity, service years, and versions of design codes. [ABSTRACT FROM AUTHOR]

Strip foundations are the most prevalently used shallow foundations in low-rise residential buildings in hilly regions. The strip foundations in many of these structures are often placed on rock slopes. In a seismic event, the behavior of the foundation–rock slope system is complex. It is characterized by a reduced bearing capacity in the strip foundation for low-intensity shaking and rock slope instability at higher seismic intensity. The quantification of this behavior is essential for the seismic design of these foundations. This work presents an analytical formulation to estimate the critical seismic loading for a given geometry and material properties of a rock slope that is represented by the Hoek–Brown (HB) failure criterion, up to which the stability of the slope is ensured. An extensive study that uses pseudo-static finite-element limit analysis (FELA) is carried out to parametrically analyze the effect of the slope angle and seismic acceleration on the seismic bearing capacity factor of a footing on rock slopes with a wide range of rock mass properties. The results of the FELA are utilized to develop a design tool (Rock-Bearing) to estimate the bearing capacity of strip foundations that are placed on rock slopes. The developed tool could be used instead of the computationally expensive numerical analysis for the preliminary design of foundations in seismically active hilly areas. Practical Applications: The assessment of the seismic bearing capacity of a geomaterial that sustains a strip foundation is a crucial element in the design of strip foundations that rest on it. Using the code-based presumptive values for the bearing capacity for the seismic design might lead to unsafe designs where the strip foundation is near the edge of a slope in hilly areas. The seismic design of these foundations demands a comprehensive analysis, which preliminarily investigates the global stability of the slope and further incorporates the effect of horizontal seismic acceleration and vicinity of the slope in the reduction of the bearing capacity. The previously illustrated design requirements demand a sophisticated analysis of the design. This work develops a design aid tool that could be used instead of the computationally expensive numerical analysis for the preliminary design of foundations in seismically active hilly areas. [ABSTRACT FROM AUTHOR]

The definition of the targeted engineering demand parameters (EDPs) is important to probabilistic seismic demand modeling (PSDM), which produces probability density functions of EDPs conditioned on seismic intensity measure (IM). The targeted EDPs are usually defined at the group level to account for multiple components/units. Thus, they are affected by the considered range of units, i.e., the sample positions. For instance, the maximum peak floor acceleration (PFA) within the whole building differs from the maximum among only the important positions related to seismic loss. Additional uncertainties are induced in the PSDM of PFA if the sample positions vary when architectural function and non‐structural elements change. In this study, the aforementioned influence is termed random‐positioned‐sampling (RPS) effect, and it is investigated by targeting a modularized suspended building, which features the tuning mechanism, multiple major modes, uneven response envelopes, and notable non‐structural‐object‐structure interactions (NSOSI). Results show that the RPS effect lowers the maximum‐based group‐level EDP and increases the dispersion within the EDP sample sets, indicating that conventional PSDMs without considering the RPS effect are biased. The significance of the influence is positively correlated to the position‐wise coefficient of variation of EDP but negatively correlated to the density of sample positions. The combined influence of the NSOSI and the RPS effect is two‐sided for PSDM. The NSOSI amplifies the RPS effect via enlarging position‐wise dispersion of EDP, whereas, the RPS effect waives part of the detrimental scattered contributions from NSOSI. Overall, the IM performance is handicapped, even with IM optimization. However, it can be compensated if architectural function region information is acquired beforehand since the sample positions are restrained. [ABSTRACT FROM AUTHOR]

This study presents a novel methodology for the seismic vulnerability assessment of ground-supported liquid storage tanks, with a particular emphasis on tanks exhibiting deformed shells. The framework is built around the development of a simplified two-degree-of-freedom (2DoF) system, specifically designed to enable efficient probabilistic analysis through incremental dynamic analysis. The 2DoF model is calibrated using detailed nonlinear finite element simulations, which account for fluid–structure interaction and complex geometric effects. This approach allows for a significant reduction in computational effort while maintaining a high level of accuracy in predicting seismic fragility. A key feature of the proposed methodology is the explicit inclusion of deformed tank geometries, which are often encountered in real cases and can critically impact seismic performance. The study identifies and quantifies the effects of these deformations on various damage states, such as local buckling, overturning, and liquid overspill. Fragility curves are developed to characterize the probability of exceeding these damage states under different levels of seismic intensity. The proposed methodology is validated through a representative case study, demonstrating its ability to capture the key features of tank behavior and provide robust fragility estimates. The results highlight the potential of the 2DoF system to serve as a practical tool for seismic risk assessment, enabling engineers and researchers to evaluate tank vulnerabilities more efficiently. [ABSTRACT FROM AUTHOR]

As large-scale depletion of shallow coal seams and increasing mining depths intensify, the frequency and intensity of mining-induced earthquake events have significantly risen. Due to the complex formation mechanisms of high-energy mining-induced earthquakes, precise identification and early warning cannot be achieved with a single monitoring method, posing severe challenges to coal mine safety. Therefore, this study conducts an in-depth risk analysis of two high-energy mining-induced earthquake events at the 3308 working face of Yangcheng Coal Mine, integrating microseismic monitoring, stress monitoring, and seismic source mechanism analysis. The results show that, by combining microseismic monitoring, seismic source mechanism inversion, and dynamic stress analysis, critical disaster-inducing factors such as fault activation, high-stress concentration zones, and remnant coal pillars were successfully identified, further revealing the roles these factors play in triggering mining-induced earthquakes. Through multi-dimensional data integration, especially the effective detection of the microseismic "silent period" as a key precursor signal before high-energy mining-induced earthquake events, a critical basis for early warning is provided. Additionally, by analyzing the spatiotemporal distribution patterns of different risk factors, high-risk areas within the mining region were identified and delineated, laying a foundation for formulating precise prevention and control strategies. The findings of this study are of significant importance for mining-induced earthquake risk management, providing effective assurance for safe production in coal mines and other mining environments with high seismic risks. The proposed analysis methods and control strategies also offer valuable insights for seismic risk management in other mining industries, ensuring safe operations and minimizing potential losses. [ABSTRACT FROM AUTHOR]

This paper considers two earthquakes which occurred on October 18, 2017 and October 25, 2017 in western Transbaikalia. In spite of the moderate energy level of both events, they can be treated as significant for the study area, because such earthquakes have been recorded there relatively rarely compared with the adjacent high-seismicity areas in the Baikal Rift Zone. The mechanisms of both earthquakes based on surface wave amplitude spectra showed that these events occurred under a dominating east–west near-horizontal compression and an inclined or nearly vertical NW‒SE tension, which is typical for western Transbaikalia. For both earthquakes, we also computed source parameters: scalar seismic moment M0 = 5.0 × 1015 N m, moment magnitude Mw = 4.4, and source depth h = 7 km for the October 18, 2017 event; M0 = 3.5 × 1015 N m, Mw = 4.3, and h = 29 km for the October 25, 2017 event. These earthquakes have caused noticeable macroseismic effects in the near-field; the maximum observed shaking intensity was IV–V (MSK-64) during the October 18, 2017 earthquake and V during the October 25, 2017 earthquake. These data were the basis for our analysis of present-day activity of faults in the study area. The results may be helpful for more accurate assessment of earthquake hazard and seismic risk in western Transbaikalia. [ABSTRACT FROM AUTHOR]

This paper presents a procedure for simplified collapse probability prediction of RC frame buildings when subjected to ground motion intensities commonly used in designing buildings. For this purpose, seismic collapse probability of a range of RC moment resisting frame buildings are assessed at the design basis earthquake (DBE) and the maximum considered earthquake (MCE) levels of seismic intensity by conducting more than a thousand nonlinear response history analyses (NRHA) using a suite of 40 seismic ground motion records. The 13 buildings included in the investigation have different heights (5–15 storeys) and footprints (3–6 bays), are designed to different target maximum inter‐storey drifts (within the code specified limit), and have critical members detailed to sustain different levels of confinement and anti‐buckling demands. The NRHA results consistently demonstrate that the design inter‐storey drift and the anti‐buckling detailing of longitudinal rebars in the critical frame members strongly influence the collapse probability of RC frame buildings. The results also show that while RC frame buildings designed to reach 2.5% (or less) inter‐storey drifts and detailed for ductile seismic performance can successfully avoid collapse at DBE, avoidance of collapse at DBE cannot be guaranteed if RC frames are designed to reach a target drift of more than 2% and not detailed for full ductility. At MCE, collapse probability is found to consistently exceed 10% unless the building is designed to incur no more than 1% plastic drift and the frame members have ductile detailing. Based on the NRHA results of the 13 case study buildings, easy‐to‐use equations relating their seismic collapse probability at MCE with the design drift and a quantifiable measure of ductile detailing are generated and validated by comparing with the collapse probability obtained by NRHA of an independent RC frame building. The proposed equations provide a rapid, yet reasonably reliable tool for performance‐based seismic design of RC frame buildings, and enable designers to estimate seismic collapse probability of RC frame buildings without having to conduct cumbersome NRHA. [ABSTRACT FROM AUTHOR]

The article discusses a long-runout loess landslide triggered by a 6.2 magnitude earthquake in Qinghai, China, resulting in significant casualties and property damage. The study highlights the geological and topographic factors controlling groundwater in the loess layer, emphasizing that long-term irrigation activities are not the primary cause of groundwater accumulation. The research aims to elucidate the failure process and motion characteristics of the landslide, providing insights into the mechanisms and prevention measures of deep-seated flows triggered by earthquakes in the region. [Extracted from the article]

This paper introduces cross-fade sampling, a computationally efficient Markov Chain Monte Carlo simulation method that uses a semi-analytical approach to quickly solve Bayesian inverse problems that do not themselves have an analytical solution. Cross-fading is efficient in two ways. First, it requires fewer samples to obtain the same quality simulation of the target probability density function (PDF). Secondly, it is much faster to evaluate the posterior probability of each sample than conventional sampling methods for simulating Bayesian posterior PDFs. Conventional methods require evaluating the prior probability (which describes your a priori constraints) and data likelihood (which describes the fit between the observations and the predictions of the model) for each sample model. However, cross-fading does not require evaluating the data likelihood, meaning that 'big data' can be fit with zero additional computational cost. Further, the cross-fading approach can be used to calculate the marginal likelihood associated with a model design, facilitating model comparison and Bayesian model averaging. Topics covered in this paper include derivation of the cross-fade approach and how it can be used to simulate Bayesian posterior PDFs and compute the marginal likelihood, discussion of the class of problems to which cross-fading can be applied (with examples from earthquake statistics, earthquake ground motion modelling, volcanic eruption forecasting, and finite fault slip modelling), demonstration of efficiency relative to existing sampling methods and discussion of how cross-fading can be used to account for prediction errors (i.e. epistemic errors) as part of the geophysical inverse problem. [ABSTRACT FROM AUTHOR]

The scientific process of earthquake forecasting involves estimating the probability and intensity of earthquakes in a specific area within a certain timeframe, based on seismic activity features and observational data. Among the various methodologies, epidemic-type aftershock sequence (ETAS) models, rooted in seismic empirical laws, stand as widely used tools for earthquake forecasting. In this study, we introduce the CL-ETAS model, a novel approach that integrates convolutional long short-term memory (ConvLSTM), a deep learning model, with the ETAS model. Specifically, we leverage the forecasting outputs of ETAS to enhance both the training and forecasting processes within the ConvLSTM framework. Through forecasting tests, our findings illustrate the effectiveness of the CL-ETAS model in capturing the trends observed in earthquake numbers (⁠|$M \ge 3$|⁠) in Southern California following three main shocks. Overall, our model outperforms both a simple ETAS model and ConvLSTM in this context. [ABSTRACT FROM AUTHOR]

For the risk analysis of spatially distributed structures, the joint prediction of ground motion intensities at multiple sites is required. Therefore, many researchers have come up with spatial correlation models for seismic intensity measures (IMs). The spatial correlation model requires site-specific non-ergodic ground motions. One of the chosen approaches for correlation studies is physics-based simulations (PBS), which account for the complexities related to earthquake source, path and site. The present study evaluates the efficiency of the artificial neural network-based broadband response spectra generator (BBANN) of Sharma et al. (2023) in terms of residual analysis and spatial correlation. The Turkey earthquakes of 6th February 2023 are taken as the case study. The model-predicted values corresponding to a short period are compared with the recorded values for the events. We found that the model was able to capture ground motion trends without any bias in residuals. Also, in the spatial correlation scale, the model predictions are comparable with recorded values. The results highlighted the efficiency of the BBANN model in effectively capturing the spatial pattern of ground motion intensity measures. The study draws attention to the ability of PBS to generate non-ergodic ground motion and, hence, can be useful in seismic hazard and risk frameworks. [ABSTRACT FROM AUTHOR]

This research aims to comprehensively estimate seismicity parameters and create seismotectonic and isoseismal maps for the state of Meghalaya, located in the North-East (NE) region of India using an earthquake catalog collected between 1861 and 2022. The seismic influence zone considered for the study is a circular area with a radius of 350 km around Shillong city (latitude 25.57° N and longitude 91.88° E). Distinct magnitude classes, such as 3.50–3.99, 4.00–4.99, 5.00–5.99, 6.00–6.99, and ≥ 7.00, are considered for analysis, and corresponding completeness periods are obtained as 40, 60, 100, 160, and 130 years, respectively. The study area seismicity parameters a and b values of the Gutenberg–Richter (G–R) relationship are obtained with values ranging from 5.50 to 6.23 and 0.70 to 0.75, respectively. This study further estimates earthquake magnitude occurrence probabilities for 1, 50, and 100 years, as well as the associated return periods. Additionally, seismotectonic maps are developed to provide crucial insights into seismic hazards within the study area. These maps delineate fault lines, active tectonic structures, and seismic zones, facilitating the assessment of potential seismic risks. Intensity-based isoseismal maps are generated to assess the influence of the past five major earthquake occurrences within the study area. It is observed that, if a recurrence of past seismic events occurs at or near the same region, a maximum intensity XI on the Medvedev–Sponheuer–Karnik (MSK) intensity scale might be felt in the study area. The outcome of this study will serve as a valuable resource for seismic hazard assessment specific to the Meghalaya region. [ABSTRACT FROM AUTHOR]

In view of the construction difficulties and other problems faced by structure construction in areas with high-altitude, high-intensity seismic regions, a dry-connection fully precast concrete frame structure was proposed. The connections in this structure eliminate the need for templates or auxiliary supports, facilitating simultaneous component installation on multiple floors and at multiple locations. This significantly reduces construction labor intensity and enhances the construction efficiency. To investigate the seismic performance of the structure, a 3-story test structure with a scale ratio of 1/2 was designed, and shaking table tests were conducted to study the dynamic characteristics and damage progression of the test structure under various intensities of earthquakes. The test results show that the structure performs well as designed. Then, a finite-element model of the structure was established, and numerical simulations were performed to investigate the seismic response characteristics and seismic vulnerability. The numerical simulation results indicated that the seismic performance of the fully precast concrete frame structure is slightly lower than that of the cast-in-place concrete frame structure, but sufficient to survive rare earthquakes without collapsing even under the action of near-field earthquakes. [ABSTRACT FROM AUTHOR]

This journal article titled "An open access dataset for strong-motion data (PGA, PGV, and Site VS30) of 2023 M6.2 Jishishan, Gansu, China earthquake" provides a dataset of strong-motion data from the 2023 M6.2 Jishishan earthquake in China. The dataset includes records of peak ground acceleration (PGA) and peak ground velocity (PGV) from 741 sensors, as well as site VS30 data. The article discusses the instruments used to collect the data and the processing scheme for the records. The authors also present methods used to estimate VS30 values for various locations in China, including field investigations and a model that incorporates observations and topographic slope. The authors compare their model to other existing models and find that it performs the best. The dataset is available online for access. The authors acknowledge their support and declare no conflicts of interest. [Extracted from the article]

This paper proposes a procedure to design low‐rise base‐isolated structures achieving a specific target level of earthquake‐induced loss (e.g., dollars, downtime) while complying with a predefined minimum level of structural reliability. The procedure is "direct" since the target loss is specified at the first step of the process, and virtually no design iterations are required. Direct loss‐based design (DLBD) is enabled by a simplified loss assessment module involving: (1) surrogate probabilistic seismic demand models representing the probability distribution of peak horizontal displacements and accelerations on top of the isolation layer conditional on different ground‐motion intensity levels; (2) approximations of the superstructure response; (3) simplified consequence models for isolation system and superstructure based on damage‐to‐loss ratios (economic loss or repair time); (4) simplified consequence models for acceleration‐ and drift‐sensitive non‐structural components, based on storey loss functions of a potential inventory of components. Given some basic geometrical parameters of the superstructure, DLBD provides the isolation system's force‐displacement curve and the required superstructure's strength complying with a selected loss target. The members' structural detailing follows the principles of direct displacement‐based design, sectional analysis, and the general theory of base isolation. The procedure is illustrated by designing six reinforced concrete wall buildings (two‐, three‐, and four‐storeys) base isolated with lead rubber bearings, to achieve predefined targets of expected repair time. Repair time is benchmarked against a more refined method adopting a cloud‐based non‐linear time history analysis, finding a maximum underestimation of 17%, thus confirming the dependability of DLBD. Such error is almost entirely attributable to the simplified estimation of peak floor accelerations, and it could be potentially eliminated by refining such estimation. [ABSTRACT FROM AUTHOR]

The slope of a linear approximation of a probabilistic seismic hazard curve, when it is represented in the log‐log scale, is a key parameter for seismic risk assessment based on closed‐form solutions, and other applications. On the other hand, it is observed that different hazard models can provide, at the same site, comparable ground shaking, yet appreciably different slopes for the same exceedance return period. Moreover, the slope at a given return period can increase or decrease from low‐ to high‐hazardous sites, depending on the models the probabilistic seismic hazard analysis (PSHA) is based on. In the study, the sensitivity of the slope to the main model components involved in PSHA was explored, that is: the earthquake rate, the magnitude and source‐to‐site distance distributions, and the value of the residual of ground motion models (GMM). With reference to a generic site, affected by an ideal seismic source zone, where magnitude follows the Gutenberg‐Richter (G‐R) relationship, it was found that the local slope of hazard curve increases with the following factors in descending order of importance: (i) increasing distance from the source; (ii) decreasing maximum magnitude and increasing b$b$‐value of the G‐R model; (iii) increasing rate of earthquakes of interest; (iv) increasing residual of the GMM. These results help explain the systematic differences in hazard curve slopes found in three authoritative hazard models for Italy, and the related impact on simplified risk assessment. [ABSTRACT FROM AUTHOR]

This article presents the results of the LNEC-3D shaking table tests on a full-scale masonry cross vault without and with the textile reinforced mortar used as strengthening solution. The specimen has been tested in the scope of the European project SERA. TA 07 "Seismic Response of Masonry Cross Vaults: Shaking table tests and numerical validations". The specimen replicates a generic cross-section of a central bay located in a lateral nave of a three-nave church, derived from the intersection of two semi-circular barrel vaults with low rise. It is representative of a generic monumental church in Central Italy, generated by a squared base groin vault with a net span of 3.13 m and 1.13 m rise at full scale. A unidirectional seismic action is applied to develop shear damage in the shell of the vault. A detailed description of the two tests and the conclusions are presented. The response is evaluated based on the displacements, damage, and collapse mechanisms developed as a function of an increasing intensity earthquake testing protocol, in which a pre-processed strong ground motion component of the L'Aquila (Italy) earthquake (April 6, 2009) was used. [ABSTRACT FROM AUTHOR]

Fragility curves are fundamental tools in seismic risk assessments, providing insights into the vulnerability of structures to earthquake-induced damages. These curves, which plot the probability of a structure reaching or exceeding various damage states against earthquake intensity, are critical for developing effective modification strategies. This review aims to present the characteristics between building- and site-specific fragility curves, which incorporate detailed local characteristics, and generic fragility curves that apply broader, more generalized parameters. We utilize the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology to systematically review the literature to address key research questions about the methodological differences, applications, and implications of these curve types in assessing seismic risks. The methods involved a comprehensive search and combination of existing studies on the topic, focusing on how these curves are developed and applied in real-world scenarios. The results from this review show that building- and site-specific curves, while more precise, require extensive data and are therefore more complex and costly to develop. In contrast, generic curves, though less accurate, offer a cost-effective solution for preliminary risk assessments over large areas. The conclusions drawn from this review suggest that while each type has its merits, the choice between building- and site-specific and generic fragility curves should be guided by the specific requirements of the seismic risk assessment task, including available resources and the need for precision in the vulnerability estimations. [ABSTRACT FROM AUTHOR]

The global energy crisis is increasingly severe, and the construction industry, as a high-energy-consuming sector, is one of the main sources of carbon emissions. As a result, the development of green buildings has become imperative. Shear walls, as a common structural form in buildings, have their wall layout ratio significantly influencing the amount of building materials used, which is crucial for material reduction and carbon emission reduction during construction. This paper innovatively introduces the concept of the optimal shear wall layout ratio, focusing on the analysis of the variation patterns of wall ratios and their associated carbon emissions in both traditional and optimal models. Various optimal models are designed with shear wall length as the variable, and the relationship between shear wall layout ratio and carbon emissions is examined. Under a seismic fortification intensity of level 7 (0.1 g), the layout ratio of the optimal models does not exceed that of the traditional model (4.24%), and the carbon emissions are reduced by approximately 11%. A reasonable design of the shear wall layout ratio not only reduces carbon emissions in buildings and improves reverse performance but also promotes a dual enhancement in both economic and environmental benefits in the construction industry. [ABSTRACT FROM AUTHOR]

With the aim of achieving a graded-protection braced frame structure and minimizing the excessive residual deformation of traditional metal dampers under intense seismic action, a graded-yield-type metal self-centering brace (SC-GYMB) is proposed. The brace is composed of X-shaped and U-shaped steel plates with different yield point displacements, which jointly dissipate energy. Additionally, it employs a composite disc spring as a self-centering element to provide restoring force for the brace. The brace's basic structure and working mechanism are described, and the theoretical model for its restoring force is derived. The ABAQUS finite element software (ABAQUS 2021) is utilized to investigate the hysteretic performance of the SC-GYMB under low-cycle reciprocating load, while thoroughly discussing the influence of various model parameters on its key mechanical behavior. The results demonstrate a strong agreement between the theoretical restoring force model and the numerical simulation results. The hysteretic curves of the braces exhibit a distinct "flag" characteristic, indicating excellent energy dissipation capacity and self-centering performance. Moreover, these curves display a hierarchical yield behavior that satisfies the seismic performance requirements for different intensity earthquakes. The deformation mechanism of X-shaped steel sheets transitions from bending deformation during the initial loading stage to tensile deformation in the subsequent loading stage. Increasing the initial pre-compression force of the combined disc spring enhances the restoration performance of the brace. Augmenting the thickness of X-shaped or U-shaped steel sheets modifies the displacement and load at both the first and second yield points, thereby enhancing energy dissipation capacity and bearing capacity of the brace; however, it also leads to increased residual deformation. [ABSTRACT FROM AUTHOR]

In earthquake-prone regions, the seismic performance assessment of reinforced concrete (RC) continuous bridges is critical for ensuring their resilience and safety. This study proposes a fragility curve developed through a hybrid pushover–incremental dynamic (PO-ID) analysis to accurately evaluate the seismic vulnerability of RC continuous bridges. The proposed method integrates the advantages of pushover analysis, which provides insights into the bridge's capacity, with incremental dynamic analysis, which captures the bridge's response under varying earthquake intensities. The resulting fragility curves offer a more comprehensive understanding of the likelihood of bridge failure at different seismic intensities. Incremental dynamic analysis (IDA) effectively illustrates a bridge's response to increasing seismic demands but does not account for ultimate displacement under static lateral loads. Pushover analysis (POA) is useful for capturing maximum displacement capacity under static forces, yet it falls short of addressing the dynamic effects of near-fault ground motions. The hybrid approach combines the strengths of both IDA and POA, and this hybrid method's heightened sensitivity to damage states allows for earlier detection and conservative displacement estimates, improving seismic assessments, informing design and retrofitting practices, and enhancing safety by addressing transverse displacements and weak axis vulnerabilities. [ABSTRACT FROM AUTHOR]

The transverse-direction post-seismic running safety of a longitudinally connected ballastless track-continuous girder bridge (LCBTCGB) system considering earthquake damage state (EDS) was studied. In this study, a simulation model of an LCBTCGB was established, and the post-earthquake damage law of the LCBTCGB was analyzed by selecting the ground motion that had the greatest influence from within the existing studies. The EDS of key interlayer components and the residual deformation law of each layer structure of the LCBTCGB system were defined. Subsequently, the residual deformations and EDS from the simulation model were imported into a coupled dynamic model of the train, track, and bridge. Evaluation of running safety evaluation after an earthquake was carried out with and without considering EDS, and a running safety guidance diagram for after an earthquake is provided. The results revealed that under conditions of rare earthquakes, without considering EDS, the running safety judgment after the earthquake were underestimated, and the risk increased by 13.6%. Following the designed earthquake, the running safety risk after the earthquake increased by 18.7% if EDS was not considered. The risk of the running safety index exceeding the limit did not increase linearly with earthquake intensity with and without considering EDS. When the EDS was considered, derailment coefficients and wheel axle lateral forces exceeded the safety limit value at an earthquake intensity of 0.2 g, whereas these limit values were only exceeded at an earthquake intensity of 0.3 g when EDS is ignored. When the earthquake intensity reached 0.5 g, the influence on the derailment coefficient was greater but the difference in the wheel axle lateral forces was not significant with or without considering EDS. It is suggested that EDS should be considered when post-seismic running safety of LCBTCGBs are analyzed; otherwise, it will lead to misjudgment of running safety after an earthquake. [ABSTRACT FROM AUTHOR]

On 18 December 2023, a 6.2-magnitude earthquake struck Jishishan, affecting multiple counties and cities in Gansu and Qinghai Provinces. The seismic intensity of the meizoseismal area was VIII, resulting in extensive structural damage and building collapses. A damage assessment was conducted of the epicenter and surrounding high-intensity zones. To understand the typical structures and characteristics of the buildings that were damaged in these high-intensity zones, this study summarizes the characteristics of the damage to typical rural houses, compares the damage of the rural houses across different sites, and analyzes the causes behind these variations. The findings of the study indicate the following: (1) Timber and some brick–timber structures, due to their age, insufficient material strength, and lack of adequate connections between parts of the building, primarily experienced severe damage or total collapse, characterized by through-wall cracks, partial collapses, or complete collapses. (2) Brick–concrete structures predominantly suffered moderate to severe damage due to factors such as improper layout, uneven façades, and inadequate or incomplete seismic measures. The observed damage included significant wall cracks and extensive damage to two-story buildings. (3) Frame structures, mainly used for public facilities like schools, hospitals, and health centers, exhibited strong integrity and excellent seismic performance, resulting in minimal to no damage, with damage largely confined to non-load-bearing components. (4) The amplification effects of seismic waves in thick loess basin areas, slope sites, and the hanging wall effect of faults exacerbated structural damage to rural houses located in certain villages within the high-intensity areas. The results of this study can serve as a reference for post-disaster reconstruction and seismic retrofitting of buildings and contribute positively to enhancing the disaster resilience of rural housing. [ABSTRACT FROM AUTHOR]

The Xianshuihe fault, located in the southeastern Tibetan Plateau, stands as one of the most active faults in China. As assessing earthquake hazard relies on access to long‐term paleoseismological archives, this paper seeks to optimize the interpretation of paleoseismological records. We retrieved nine sediment cores from three lakes over a 30 km fault segment. Earthquake‐related deposits were identified through grain‐size analysis, XRF core scanning, and SEM observations of thin sections. Age models based on short‐lived radionuclides correlate these events with historical earthquakes, which are recorded with varying sensitivities to seismic intensity across the three lakes. We developed a code that evaluates the plausibility of rupture scenarios against sedimentary evidence: Each site is used as a binary paleoseismometer, indicating whether or not an earthquake reached a local intensity threshold. The combined evidence from the three sites allows to evaluate rupture scenarios on the Xianshuihe fault, according to rupture length‐magnitude scaling laws and intensity prediction equations. The most probable scenarios allow to discriminate the rupture area and magnitude range providing a good agreement with historical reconstructions. Our work demonstrates the potential of combining earthquake records to infer the magnitude and rupture zone of paleo‐earthquakes, even with a limited data set. Our approach, applicable across diverse geological settings and timescales, offers enhanced precision in understanding long‐term paleoseismology covering multiple earthquake cycles. However, establishing the synchronicity of events in such an active area—where earthquake return times are typically <100 years—demands highly accurate age models, which remains challenging. Key Points: Multi‐proxy analysis and short‐lived radioelement dating revealed earthquake deposits in three small mountain lakes in SE TibetThe lakes documented the historical seismicity of the Xianshuihe fault, showing varying sensitivities to seismic intensitiesComparing lacustrine records, a code using seismic scaling laws and fault geometry could discriminate possible paleo‐earthquake locations [ABSTRACT FROM AUTHOR]

Jailolo, the capital of West Halmahera Regency, faces earthquake risks due to its proximity to a Jailolo volcano and a double subduction zone in Eastern Indonesia. This study is aimed at investigating the seismic hazard characteristics in Jailolo through the analysis of statistic and signal parameters. Analyzing seismic hazard characteristics in this region is crucial for assessing earthquake risks and understanding how local soil conditions influence ground shaking. Earthquake catalogs from several databases spanning from 1970 to 2018 were utilized. Additionally, 40 locations around Jailolo were surveyed using a short‐period seismometer to gather microtremor data. The earthquake catalogs underwent b value analysis using the maximum likelihood method, while microtremor data were examined for f0 and A0 using the horizontal‐to‐vertical spectrum ratio (HVSR) method. VS30 profiles were derived using the H/V curve inversion method. The b value characterizes earthquake size distribution, HVSR evaluates ground properties, especially the shallow subsurface, and VS30 represents the time‐averaged shear wave velocity in the upper 30 m of the Earth's surface. The findings revealed the average b value around Jailolo is 1.36 with a 15% deviation, categorizing the area as earthquake prone and volcanic. The values of f0 and A0 ranged from 0.536 to 2.44 Hz and 8.97 to 21.2, respectively. The results of f0 and A0 suggested that the Jailolo area is predominantly characterized by thick sediment. The H/V curve analysis provided a VS30 profile ranging from 109 to 460 m/s, indicating that the area is dominated by sediment consisting of stiff soil, very dense soil, and soft rock. In conclusion, Jailolo is highly prone to earthquakes due to its seismic and volcanic activity, supported by soil characteristics that can amplify seismic waves and increase ground shaking intensity during earthquakes. These findings stress the need for long‐term seismic monitoring and community involvement to mitigate seismic risks. [ABSTRACT FROM AUTHOR]

The nonlinearity of the ballastless track-simply supported girder bridge primarily manifests in the bearings and track structure during earthquakes. While existing research has elucidated the effects of bearing nonlinearity on running safety during earthquakes, the effects of track structure nonlinearity remain unclear. Therefore, this study further explores the effects of track structure nonlinearity on running safety during earthquakes. First, a dynamic analysis of the train–track–bridge coupled system (TTBCS) incorporating track structure nonlinearity, was performed using the ANSYS-TRBF (train–rail–bridge-foundation coupled system dynamic analysis software, TRBF) co-simulation approach to assess running safety during earthquakes. Then, by comparing results from the TTBCS models both with and without track structure nonlinearity, this study clarified the effects of track structure nonlinearity on dynamic response and running safety assessment (RSA) indices. It was found that neglecting track structure nonlinearity during earthquakes can result in an overestimation of the Nadal, leading to an inaccurate RSA. Moreover, this effect intensifies as the seismic intensity increases. By explaining these results, this study elucidates the mechanism by which track structure nonlinearity affects running safety. Finally, this study specified the necessary seismic intensities and vehicle speed ranges needed to consider track structure nonlinearity, and established a comprehensive influence domain. This study reveals the effects of track structure nonlinearity on running safety during earthquakes, contributing to a more accurate RSA during earthquakes. [ABSTRACT FROM AUTHOR]

Taking the typical brick–wood structure houses in northern China as the research object, two 1/2‐scale brick–wood structure house models with the same size and layout were tested using large‐scale shaking table test technology. Model 1 has seismic measures of ring beams, structural columns, wall tie bars, reinforced concrete lintels for doors and windows, and purlin bottom plates. Model 2 has the same structural layout, dimensions, and construction technical conditions as Model 1 but lacks the seismic measures of ring beams and structural columns as Model 1, and the other construction measures are the same. In the test, the Wenchuan record, EL‐Centro record, and Lanzhou artificial record were selected to simulate the horizontal seismic action on the models. Through the analysis and comparison of the seismic damage process and seismic response characteristics of the two models, the results showed that horizontal shear failure was the main failure mode of single‐story brick–wood houses, and the protruding gable wall parts of the crosswall were the weak points for seismic resistance. The seismic measures adopted in the test effectively improved the seismic performance of the houses, with Model 1 and Model 2 achieving the basic seismic fortification of intensity VIII and IX, respectively. The relevant research results presented in this paper clarify the seismic response law and seismic failure mechanism of brick–wood houses. Meanwhile, the corresponding seismic technical measures proposed based on these results have certain guiding significance for the construction of suburban or rural houses. [ABSTRACT FROM AUTHOR]

Two new structure-specific scalar intensity measures for plane reinforced concrete moment resisting frames under far-fault ground motions are proposed. These intensity measures, of the spectral acceleration and spectral displacement type, are characterized as multi-modal and multi-level. They encompass the effects of the first four natural periods and are defined for four performance levels, including considerations of inelasticity up to the collapse prevention level. This is achieved with the aid of equivalent linear modal damping ratios previously developed by the authors for performance-based seismic design purposes. These modal damping ratios, dependent on period, soil type, and deformation, are associated with the transformation of the original multi-degree-of-freedom (MDOF) nonlinear structure into an equivalent MDOF linear one. The proposed intensity measures are conceptualized to be simple and elegant, incorporating all the aforementioned features rationally, without the artificial combination of terms, definition of period ranges, or addition of coefficients determined by optimization procedures. This approach sets it apart from existing measures that attempt to account for multiple modes and inelasticity. A comparison of the proposed intensity measures against ten of the most popular existing ones in the literature, focusing on efficiency, practicality, proficiency, scaling robustness and sufficiency, demonstrate their advantages. [ABSTRACT FROM AUTHOR]

ASMI, the Italian Archive of Historical Earthquake Data, is a data collection distributed online that provides seismological data on more than 6600 earthquakes that occurred in the Italian peninsula and surrounding areas from 461 BC to the present day, based on more than 460 seismological data sources. ASMI is the Italian node of AHEAD, the European Archive of Historical Earthquake Data, which is, in turn, the European node providing data on historical earthquakes to EPOS ERIC, the European Plate Observing System, a European Research Infrastructure Consortium. ASMI distributes earthquake parameters, sets of macroseismic intensity data and other details about earthquake effects, together with the bibliographical reference of the data source and, if possible the data source itself. ASMI's web portal allows users to query the data by earthquake or by data source, and to download the earthquake parameters and macroseismic intensities and represent them on interactive maps and tables. ASMI is updated regularly with new data on past and recent earthquakes. ASMI is the basic source of data for the Italian Macroseismic Database (DBMI) and the Parametric Catalogue of Italian Earthquakes (CPTI). This article describes the archive content and structure, its main features and functionalities, and its potential seismological research applications. [ABSTRACT FROM AUTHOR]

This study presents the development and analysis of high damping rubber bearings (HDRBs) with enhanced stiffness properties to improve seismic isolation performance. The proposed HDRBs exhibit displacement-dependent nonlinear stiffness and significant damping effects, especially under large deformations caused by various seismic events. A deformation history integral model, calibrated with experimental data, is employed to accurately simulate the mechanical behavior and stiffness-damping characteristics of the HDRBs. The numerical simulations are validated through experimental tests, providing a solid basis for parameter design and performance assessment. The results show that the equivalent stiffness coefficient of the HDRBs increases with deformation amplitude, effectively limiting extreme deformations. Parametric analyses and case studies across a wide range of earthquake scenarios demonstrate that the enhanced stiffness and high damping effects of HDRBs significantly improve seismic isolation efficiency while controlling isolation layer displacement. The performance-based design methodology developed in this research effectively limits bearing deformation, thereby preventing potential superstructure failures. Moreover, the adaptive characteristics of the HDRBs allow for the adjustment of deformation levels according to seismic intensity, ensuring the structural safety of buildings under varying earthquake conditions. [ABSTRACT FROM AUTHOR]

A shallow sub‐seafloor seismic model that includes well‐determined seismic velocities and clarifies sediment‐crust discontinuities is needed to characterize the physical properties of marine sediments and the oceanic crust and to serve as a reference for deeper seismic modeling endeavors. This study estimates the seismic structure of marine sediments and the shallow oceanic crust of the Alaska‐Aleutian subduction zone at the Alaska Peninsula, using data from the Alaska Amphibious Community Seismic Experiment (AACSE). We measure seafloor compliance and Ps converted wave delays from AACSE ocean‐bottom seismometers (OBS) and seafloor pressure data and interpret these measurements using a joint Bayesian Monte Carlo inversion to produce a sub‐seafloor S‐wave velocity model beneath each available OBS station. The sediment thickness across the array varies considerably, ranging from about 50 m to 2.80 km, with the thickest sediment located in the continental slope. Lithological composition plays an important role in shaping the seismic properties of seafloor sediment. Deep‐sea deposits on the incoming plate, which contain biogenic materials, tend to have reduced S‐wave velocities, contrasting with the clay‐rich sediments in the shallow continental shelf and continental slope. A difference in S‐wave velocities is observed for upper oceanic crust formed at fast‐rate (Shumagin) and intermediate‐rate (Semidi) spreading centers. The reduced S‐wave velocities in the Semidi crust may be caused by increased faulting and possible lithological variations, related to a previous period of intermediate‐rate spreading. Plain Language Summary: Sediment input has been regarded as a "lubricant" that smooths the subduction interface, allowing earthquakes to rupture over large horizontal distances and resulting in large earthquakes. Variations in sediment properties have been correlated with heterogeneity in the intensity and frequency of earthquakes along the Alaska‐Aleutian subduction zone. Here, we produce a shear‐wave velocity (Vs) model of seafloor sediment and the shallow oceanic crust along the Alaska Peninsula using ocean‐bottom seismic and seafloor pressure data from the Alaska Amphibious Community Seismic Experiment. Lithological composition significantly influences the seismic properties of seafloor sediment, and the deep‐sea seafloor sediments that include biogenic materials are characterized by reduced Vs, differing from the shallow‐water clay‐rich sediments. In addition, we observe a difference in the shear‐wave velocity of the shallow oceanic crust between the Shumagin and Semidi segments of the Alaskan margin, which might be evidence of varying seafloor spreading rates during previous plate reorganizations. Key Points: Sub‐seafloor Vs model offshore the Alaska Peninsula is constructed using a joint inversion of seafloor compliance and Ps delaysSeismic properties of the seafloor sediments correlate with lithological composition, with the deep‐sea sediments showing reduced VsThe upper oceanic crust of the Semidi exhibits lower Vs than the Shumagin, possibly related to different seafloor spreading rates [ABSTRACT FROM AUTHOR]

To study the evolution mechanism of fracture failure on dangling concrete pavement slab in high seismic intensity areas along river during operation, the formation process of cracks at the top and bottom of dangling concrete pavement slab in high seismic intensity areas along river was analyzed, and the dangling concrete pavement slab generated by river erosion was studied through fracture mechanics. By establishing the physical and mechanical models of the dangling pavement along the river in high seismic intensity areas, the dangling pavement slab model of the double-crack primary control structural surface was obtained. With the fracture mechanics double-crack model of dangling pavement slab along river in high seismic intensity areas, the forces at different acting positions were divided into physical forces and surface forces through elastic theory. The corresponding type I stress intensity factors K I S and K I V and type II stress intensity factors K II S and K II V were calculated, respectively. According to the superposition principle of stress intensity factors, KI and KII were obtained. For the fracture problem of plane composite materials under the action of types I and II loads, the joint stress intensity factor Ke can be obtained from the maximum tensile stress criterion satisfied by any point in the cracking direction of the main control structure. Through the example analysis, the variation law of the stability coefficients of the double-crack main control structure surface in the dangling concrete pavement slab under different seismic intensities, vehicles, and action positions was obtained. The recommended driving values for the dangling pavement slab were given by backward pushing method. Finally, numerical simulation for correlation verification was carried out. In this paper, the double-crack main control structural plane of the dangling concrete pavement slab is regarded as the vertical form of the top and bottom sections. Furthermore, follow-up studies will be conducted on the fracture damage problem of the dangling concrete pavement slabs with more complex multi-crack main control structures. [ABSTRACT FROM AUTHOR]

As mining activities are expected to develop at greater depths, seismic responses to the blasting of development drift segments are expected to increase and present a greater hazard. A database of 379 development blasts was created for a mining site, recording seismic responses related to these blasts and rock mass structural and geologic properties associated with the drift segment. A random forest, multivariate statistical predictive model was developed with 75% of the drift segments. The model's performance was validated by analyzing 100 drift segments that were not used to create the model. The improved understanding of the variation in the intensity of seismic responses to development blasting through the sum of the seismic moment of the events is a clear benefit of random forest model development for the case study. In addition, the development of the predictive random forest model provides a tool for decision-makers to select performance criteria thresholds that they deem acceptable. The threshold selected would depend on the risk appetite of the decision-makers. The proposed approach provides quantitative data on the distribution of seismic hazards associated with development blasting which managers can rely on. Combining the proposed approach with current seismic protocols used at different mine sites could improve our management of seismic risk associated with development blasting. Using the predictive model for the sector and period studied has shown a potential to increase the accuracy, sensitivity, and precision for anticipating a high-intensity seismic response to a development blast. Highlights: This paper demonstrates the potential benefits of considering geologic and structural properties of the rock mass for managing seismic hazards associated with development blasting. The paper shows how developing predictive random forest models could be used to understand, manage, and communicate the seismic hazard related to blasting of development drift. The random forest models developed with the training data were used to establish thresholds for different risk levels. These thresholds were then applied to the test data to evaluate the actual performance of the models in terms of accuracy, sensitivity, precision, and F1-score at different risk appetite levels. Using the predictive model for the studied period could have increased the accuracy, sensitivity, and precision for anticipating a high-intensity seismic response to a development blast (log (ΣM0)). [ABSTRACT FROM AUTHOR]

Purpose: The primary goal of this research is to evaluate the seismic performance of Asla Hocine Primary School, a heritage school building in Annaba, Algeria, to prevent additional damage during future earthquakes in the region. The study aims to guide decision-makers in strengthening weak parts or elements in the building, implementing preventive measures and ultimately reducing earthquake disaster risk by mitigating vulnerability. Design/methodology/approach: The research employs the 3Muri software to model the seismic behavior and structural failures of the school's elements. An integrated multimodal pushover analysis is used to generate the non-linear capacity curve of the school to assess its seismic performance. The seismic demand is determined based on Algerian seismic regulations, with peak ground acceleration derived from a probabilistic seismic hazard analysis of Annaba city for return periods of 100, 200 and 500 years. The study develops three seismic scenarios to evaluate performance levels and expected damage probabilities. Findings: The study reveals that the Asla Hocine Primary School faces a high risk of damage and potential collapse under the expected seismic hazard of the region. The analysis indicates variable resilience across different seismic return periods (100, 200 and 500 years), with the performance level degrading from life safety to collapse prevention and total collapse under increasing seismic intensity. This underscores the need for targeted structural analysis and potential retrofitting to enhance the building's seismic robustness. Research limitations/implications: The paper encouraged to account for soil-structure interaction in similar studies, as it can significantly affect the overall seismic performance of buildings. Furthermore, conducting out-of-plane analysis when necessary can offer valuable insights into the structural behavior of specific components. Practical implications: The insights provided by this study contribute vital data toward conservation efforts and risk mitigation strategies for heritage structures in seismic zones. The findings are intended to guide decision-makers in implementing preventive measures and strengthening weak parts or elements in the studied school building, ultimately reducing earthquake disaster risk by mitigating vulnerability. Originality/value: This research offers a comprehensive framework for assessing the seismic vulnerability of heritage schools using detailed modeling and analysis. It highlights the importance of considering return periods of seismic events in assessing a building's seismic performance and provides a deeper understanding of the structural response to seismic stresses at both macrostructural and individual element levels. The study emphasizes the critical need for seismic risk assessment and targeted retrofitting to preserve cultural heritage assets and ensure their continued use. [ABSTRACT FROM AUTHOR]

The increasing intensity of earthquakes in West Sumatra could trigger megathrust earthquakes and tsunamis at the interplate in the Mentawai Islands. Building assessments are necessary to determine their vulnerability to predicted earthquakes. The target is a four-story building that serves as an education building and vertical evacuation. This research proposes a complete vulnerability assessment method using single microtremor observations, and the results are used to determine seismic building performance. The natural frequency is derived from the spectral analysis of the horizontal components (NS and EW) for each level, and we considered the largest earthquake peak ground motion (PGA) in this region to be the September 30, 2009, Padang earthquake (PGA 380 gals as ground motion input). We calculated the resonance index, seismic vulnerability index, and damping ratio. The results show that the resonance index of the structure is less than 1, the vulnerability index of the UNP Faculty of Economics building ɤ > (1/100-1/200) and is 1/234 to 1/699 for the x direction and 1/207 to 1/709 for the y direction; the average damping ratio is <5% for both directions (x, y) and RDM and FSR relationship is 0.78 and 0.69 for x and y respectively. The overall findings indicate that the structural response of the evaluated buildings falls within the 'slight' damage category during seismic events. [ABSTRACT FROM AUTHOR]

The aim of this study is to experimentally and theoretically investigate the behavior of a three-story fragment of a frame building constructed using the PGF-SIKF system—Prefabricated girderless frame with seismic-isolating kinematic foundations. Magnetic dampers are employed at the support level. The novelty of the research lies in the combination of a girderless frame with kinematic foundations and innovative magnetic dampers. The experimental research method involved loading the system with horizontal static force using a stationary winch, followed by the release of the load. Vibration measurements were recorded using a digital measurement system. The normative live load was simulated by applying additional static load. It was determined that the oscillation period varies between 1.8 and 2.1 seconds, depending on the amplitude of the impact. The dissipative characteristics of the seismic isolation system were obtained, with acceleration values during the testing phases ranging from 95 to 177 cm/s². The experimental results confirmed that the building fragment showed no visible damage. The logarithmic decrement of oscillations was found to range between 0.08 and 0.16. Theoretical studies involved calculations based on a sample of 14 real accelerograms, with parameters corresponding to the magnitudes of local earthquakes (M=6), the maximum magnitude expected in Shymkent. The main result is the reduction of seismic loads achieved by using kinematic foundations in the girderless frame system. It was established that, under 7-8 intensity seismic events, the average displacements at the foundation level will not exceed the experimental values. [ABSTRACT FROM AUTHOR]

Iran is located in a seismically active region, which poses a significant threat of destructive earthquakes. Given the dense populations they support and their structural importance, schools demand resilience across various dimensions. In this study, we aimed to evaluate the seismic performance of schools in Khorramabad, Lorestan, Iran, by obtaining resilience curves. The research involved a thorough analysis of retrofitting options for a specific school, identified through a review of data from Lorestan province. Three retrofitting options were considered: (1) bracing, (2) friction dampers, and (3) utilization of fiber-reinforced polymers (FRP) in the columns. The structure was modeled and designed using suitable software before and after implementing the retrofitting options. Incremental dynamic analysis (IDA) was conducted using recommended ground motions (including 10 ground motions for near and far fields). Subsequently, a risk analysis of the study area was performed, and a comparison was made between damage and fragility curves under different conditions; this included an assessment of potential damage in future earthquakes. The results demonstrated the efficacy of the analysis method in evaluating the seismic performance of buildings. Last, the study highlighted the building's response under different earthquake intensities and confirmed that the maximum capacity determined closely corresponded to findings from other nonlinear analyses. This approach was proven to be highly effective in assessing a building's behavior and ultimate capacity in the face of earthquakes. [ABSTRACT FROM AUTHOR]

Hydraulic tunnels are prone to pass through faults and high-intensity earthquake areas, which will cause serious damage under fault dislocation and earthquake action. Fault dislocation and seismic excitation are often considered separately in previous studies. For tectonic earthquakes with higher frequency in seismic phenomena, fault dislocation and ground motion are often associated, and fault dislocation is usually the cause of earthquake occurrence, so it is limiting to consider the two separately. Moreover, strong earthquake records show that there will be significant differences in the mainland vibration within 50 m. The uniform ground motion inputs in previous studies are not suitable for long hydraulic tunnels. This paper begins with the simulation of non-uniform stochastic seismic excitations that consider spatial correlation. Based on stochastic vibration theory, multiple multi-point acceleration time-history curves that can reflect traveling wave effects, coherence effects, attenuation effects, and non-stationary characteristics are synthesized. Furthermore, a fault velocity function is introduced to account for the velocity effect of fault dislocation. Finally, numerical analyses of the response patterns of the tunnel lining under four different conditions are conducted based on an actual engineering project. The results indicate the following: (a) the maximum lining response values occur under the combined effects of fault dislocation and non-uniform seismic excitation, indicating its importance in the seismic resistance of the tunnel. (b) Compared to uniform seismic excitation, the peak displacement of the tunnel under non-uniform seismic excitation increases by up to 6.42%, and the peak maximum principal stress increases by up to 28%. Additionally, longer tunnels exhibit a noticeable delay effect in axial deformation during an earthquake. (c) Under non-uniform seismic excitation, the larger the fault dislocation magnitude, the greater the peak displacement and peak maximum principal stress at the monitoring points of the lining. The simulation results show that the extreme response values primarily occur at the crown and haunches of the tunnel, which require special attention. The research can provide valuable references for the seismic design of cross-fault tunnels. [ABSTRACT FROM AUTHOR]

This article presents a summary of the damage observed in bridges in the regions affected by the 6 February 2023 Kahramanmaras, Türkiye earthquake sequence. A bridge database was developed based on the observations from multiple reconnaissance groups that visited the bridges. These reconnaissance groups collectively visited 140 individual bridges that were subjected to various intensities of ground shaking. The severity of the observed damage ranged from no damage to total collapse. The types of damage to bridge components mainly included cracking and shifting of abutments, failure of pier cap shear blocks, shifting or dislodging of bearing pads, cracking of girders and loss of prestress, plastic hinging at pier bases, residual pier drift, and distress to deck surfaces, handrails, and carried utilities. Recorded and estimated seismic intensity measures are presented for each bridge site, and statistical information and correlations were developed considering the intensity of shaking, bridge parameters, and observed damage. Observations from a few visited sites are presented as case studies to illustrate the common failure mechanisms. The bridge database and presented results are expected to serve as a reference for further analysis, such as statistical verification, correlation, or damage estimations, and discussion regarding the mitigation of the observed vulnerabilities of bridges in Türkiye and those with similar construction worldwide. [ABSTRACT FROM AUTHOR]

The earthquake sequence that occurred on 6 February 2023 in Türkiye, Kahramanmaraş, had a significant impact on 140 dams, most of which are located within a distance of 50 km from surface projection of the fault rupture. These dams experienced moderate to high levels of seismic intensity, with peak ground acceleration (PGA) estimated to vary between 0.1 and 1.3 g during the Pazarcık earthquake and 0.15 to 0.45 g during the Elbistan earthquake, depending on their proximity to the fault rupture. Although all dams were able to maintain water-retaining capabilities, some of them suffered from moderate to large permanent deformations. As part of the emergency response measures, the water levels at two of these dams, namely Sultansuyu and Arıklıkaş, were lowered in a controlled manner. Following the earthquakes, a comprehensive survey of all hydraulic structures within the influence zone was conducted, and the findings are represented in this study. These findings revealed that earthfill and rockfill dams sustained more significant damage compared with concrete dams, particularly in areas close to the fault rupture, where the shaking intensity was most pronounced. The amount of permanent displacements was observed to consistently increase with the height of the dam's transverse section. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on an innovative timber‐based retrofit solution for reinforced concrete (RC) framed buildings, with or without masonry infills. The intervention aims to enhance seismic resistance through a light, cost‐effective, sustainable, and reversible approach integrating energy efficiency upgrades. The method employs cross‐laminated timber (CLT) panels as infills or external retrofitting elements, mechanically connected to the RC frame through steel fasteners. The system is combined with thermal insulation for improved energy efficiency. The seismic performance of the proposed retrofit technique was assessed experimentally on a full‐scale building model at the European Laboratory for Structural Assessment (ELSA). The experiments included tests on two five‐story building configurations: a masonry‐infilled RC building as a reference and the same structure strengthened with CLT panels. Each building was subjected to unidirectional earthquake simulations of increasing intensity using the pseudodynamic (PsD) testing method with substructuring. The physical substructure of the hybrid model consisted of the first story of a two‐story mockup built and retrofitted in the laboratory, while stories two to five were simulated numerically. The paper discusses major observations from the tests, comparing the damage evolution and hysteretic responses of the two configurations. The experiments yielded promising results, showing that the suggested retrofit solution significantly increased displacement and energy dissipation capacity. The retrofitted building survived earthquake intensities up to 50% higher than the non‐retrofitted counterpart, exhibiting only slight structural damage. These pioneering experiments provide compelling data on the high effectiveness of the proposed CLT‐based retrofit system in enhancing the seismic performance of full‐scale RC buildings. [ABSTRACT FROM AUTHOR]

Many methods for seismic risk assessment rely on the selection of a seismic intensity measure (IM) and the development of models of the seismic demand conditional on the IM. The individual importance of these two features to accurately assess seismic performance is well known. In contrast, this study aims to evaluate the impact that the combined selection of IM and the demand model has on risk estimates. Using a hypothetical seismic source model and a non‐stationary stochastic ground‐motion model, we present risk estimates for a mid‐rise steel structure for 15 different IMs and five demand models derived by cloud analysis (four based on regression and a fifth based on an empirical binning approach). The impact of these choices is investigated through a novel method of model performance evaluation using a benchmark solution obtained via the unconditional approach (i.e., directly estimating demand exceedance frequencies from simulated ground motion time histories). The obtained results are also compared against traditional IM performance metrics, for example, efficiency and sufficiency. Finally, we demonstrate how risk estimate inaccuracies are propagated by performing a damage assessment on two example components. The results show that, for the scenario under investigation, Arias intensity combined with the binned demand model provides the best risk estimates, if sufficient samples are available, whilst ground displacement and duration‐based IMs ranked worst, irrespective of the demand model. The findings highlight the importance and interconnectedness of the selection of the IM and the demand model when using cloud analysis and present a clear method of determining the most accurate combination for risk assessments. [ABSTRACT FROM AUTHOR]

Floods caused by dam failures can cause huge losses of life and property, especially in estuarine areas and valleys. In spite of all the capabilities and great improvements reached by man in the construction of dams and their structures, they will remain helpless before the powerful forces of nature, especially those related to tectonic activation, and the occurrence of earthquakes of different intensities. The region extending from the Ilisu Dam in Turkey to the Mosul Dam in Iraq was chosen as an area for this study, and the HEC-RAS application was used to simulate the collapse of the Ilisu Dam due to a major earthquake, to know the magnitude of the risks and losses that could result from this. The Ilisu Dam was built very close to a highly tectonically active fault system, particularly the East Anatolian Fault (EAF), which is one of the largest tectonically active faults in the world with a length of 500 km. This region has witnessed past and present earthquakes of high magnitude (M > 7), especially in the EAF, so the construction of the Ilisu Dam near the EAF fault system is of great concern, as it was built in a basin with very complex seismic activity and geology. Using the HEC-RAS simulation application, the study found that the flood resulting from the collapse of the Ilisu Dam would reach the edges of the Mosul Dam Lake in just 13 h. With a flow of more than 100,000 m3/s, more than 10 billion m3 of water will flow into the Mosul Dam Lake within four days of the disaster. This will lead to the collapse of the Mosul Dam and direct the flood wave of the collapse of these dams towards Baghdad through Mosul, Tikrit, and Samarra. This could pose risks to all Iraqi cities located within the Iraqi sedimentary plain (Mesopotamia), from south of the Mosul Dam up to Basra, in a scenario similar to Noah's Flood. [ABSTRACT FROM AUTHOR]

Back-to-back mechanically stabilized earth walls (BBMSEWs) are a specialized type of reinforced soil structure widely employed in the stabilization of embankments, roads, and bridge abutments. Despite their prevalent use, the technical understanding of these structures, particularly their seismic performance, remains limited. Given the inherent randomness of earthquakes, the seismic response of structures is often evaluated probabilistically, with fragility curves serving as a popular tool for assessing the likelihood of varying degrees of damage or failure. In this study, a specific BBMSEW configuration is simulated and validated using FLAC2D software. Following this, nonlinear dynamic analyses are performed to develop both scalar and vector fragility curves, based on peak ground acceleration (PGA) and peak ground velocity (PGV), under far-field and near-field seismic conditions. The study further investigates the influence of metal strip overlap length on the vulnerability of these walls. The results not only facilitate the prediction of wall vulnerability across different seismic intensities but also reveal that increasing the overlap length of the metal strips from 0.65 to 0.85 times the wall height can reduce the probability of seismic damage by up to 35% in far-field earthquakes and up to 50% in near-field earthquakes. Moreover, the study finds that vector fragility curves provide a more realistic assessment compared to scalar fragility curves. [ABSTRACT FROM AUTHOR]

Although the wind load is usually adopted as the governing lateral load in the design of transmission towers, many tall transmission towers may be damaged or even collapse in high seismic intensity areas, especially under near-fault pulse-like ground motions. To study the seismic vibration control effect of a tuned mass damper (TMD) attached to transmission tower, parametric analyses are conducted in SAP2000 through CSI OAPI programming, including TMD parameters such as the mass ratio μ from 0.5% to 10%, the frequency ratio f from 0.7 to 1.2, and the damping ratio ξ from 0.01 to 0.2. Based on the obtained analysis results, artificial neural network (ANN) is trained to predict the vibration reduction ratios of peak responses and the corresponding vibration reduction cost. Finally, the NSGA-III algorithm is adopted to perform the multi-objective optimization of a transmission tower equipped with TMD. Results show that the vibration reduction ratios first increase and then decrease with the increase of frequency ratio, but first increase and then remain stable with the increase of mass ratio and damping ratio. In addition, ANN fitting can accurately predict the nonlinear relationship between TMD parameters and objective functions. Through multi-objective optimization with the NSGA-III algorithm, TMD can simultaneously and significantly reduce different peak responses of transmission towers under near-fault pulse-like ground motions in a cost-effective manner. [ABSTRACT FROM AUTHOR]

Pile and anchor structures are extensively employed for slope stabilization. However, their dynamic response under seismic loading remains unclear and current seismic designs primarily use the pseudo-static method. Here, a three-dimensional numerical simulation of the dynamic behavior of a bedding rock slope supported by pile–anchor systems under earthquakes is conducted. The dynamic calculation for the slope subjected to seismic forces with varying excitation directions and acceleration amplitudes is performed. The dynamic behavior of both the slope and the pile–anchor system is investigated with respect to the slope's failure mode, the dynamic soil pressure behind the pile, the anchor axial force, the bending moment, and the lateral displacement of the pile. The results indicate that the anti-slide piles cause a reflective and superposition effect on seismic waves within weak rock layers. As the input seismic intensity increases, the axial force in the anchor cables also increases, with the peak axial force occurring during the main energy phase of the seismic waves. The dynamic soil pressure acting behind the piles varies with the stratification of the slope rock layers, with lower peak dynamic earth pressure observed in weak layers. The weak layers on the slope surface experience through-shear failure. Under strong seismic loading, the structural element state undergoes significant changes. [ABSTRACT FROM AUTHOR]

In recent years, numerous studies highlighted the crucial role of the soil–structure interaction (SSI) in the seismic performance of basement structures. However, there remains a limited understanding of how this interaction affects buildings with basement structures under varying site conditions. Based on the three-dimensional (3D) numerical analysis method, the influence of the SSI on the seismic response of high-rise steel frame–core wall (SFCW) structures situated on shallow-box foundations were investigated in this study. To further investigate the effects of the SSI and site conditions, three types of soil profiles—soft, medium, and hard—were considered, along with a fixed-foundation model. The results were compared in terms of the maximum lateral displacement, inter-story drift ratio (IDR), acceleration amplification coefficient, and tensile damage for the SFCW structure under different site conditions, with both fixed-base and shallow-box foundation configurations. The findings highlight that the site conditions significantly affected the seismic performance of the SFCW structure, particularly in the soft soil, which increased the lateral deflection and inter-story drift. Moreover, compared with non-pulse-like ground motion, pulse-like ground motion resulted in a higher acceleration amplification coefficient and greater structural response in the SFCW structure. The RC core wall–basement slab junction was a critical region of stress concentration that exhibited a high sensitivity to the site conditions. Additionally, the maximum IDRs showed a more significant variation at incidence angles between 20 and 30 degrees, with a more pronounced effect at a seismic input intensity of 0.3 g than at 0.2 g. [ABSTRACT FROM AUTHOR]

In the twenty-first century, the seismic design of buildings seems to have become a fully recognized topic. There are guidelines and standards which should be taken into account by designers in seismic areas. Designers using modern international guidelines have ascertained that the behavior of structures is not as expected. New challenges in the construction industry result in the construction of structures with new, unusual shapes. These are structures that do not meet the assumptions of safe construction in seismic areas. Contemporary buildings are also characterized by their irregular distribution of structural elements. Such solutions are not beneficial from the point of view of seismic engineering and can lead to reduced dynamic resistance and damage in such structures. In this paper, a five-storey, irregular-shaped reinforced concrete (RC) building model was subjected to different earthquakes with varying magnitudes, PGA (peak ground acceleration) and PGV (peak ground velocity) values, and durations of the intense shock phase. Once the model was verified using previous in situ measurements, the building model was subjected to five earthquakes. A numerical nonlinear analysis of the building was performed using a verified FEA (finite element analysis) model in the time domain through non-linear time history analysis with the Broyden–Fletcher–Goldfarb–Shanno (BFGS) method. The building's dynamic properties were measured using various methods of excitation. The model was influenced, among others, by two far-field representative events caused by the last earthquake in Turkey, which resulted in strong ground motion. The analysis results identified the locations of structural damage and allowed for the assessment of the structure's dynamic resistance. The results of the calculations prove that the duration of the intensive phase of extortion is one of the reasons for building damage in earthquake-prone areas. Building damage occurs with earthquakes that are characterized by an intensive phase of excitation with a long duration and high values of velocity in the earthquake components. The article highlights the inadequate dynamic resistance of the building, leading to excessive displacements and unfavorable structural solutions. Damage to buildings at this earthquake intensity caused damage to the load-bearing structure, which was not designed for such intensities. This paper is a research report with a specific case study of medium-rise irregular RC buildings. [ABSTRACT FROM AUTHOR]