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A seismic vibration control system, consisting of a swing story substructure, a lateral force resisting substructure and connecting dampers, is recently proposed. The analytical model and optimization method based on the stability maximization and H2 criteria have been established. In this paper, excellent vibration control effects of the proposed system are verified through the small-scale shaking table tests on a two-story model. Experimental results demonstrate the accuracy of the analytical model and the validity of the vibration control strategy. Through numerical analyses of benchmark structures, the input energy of the optimally designed system is remarkably mitigated, and favorable vibration control effects for reducing both inter-story drifts and absolute floor accelerations under earthquake ground motions are verified by comparing with conventional moment-resisting frame structures. In addition, significant control effects can be achieved when the optimal stiffness is greater than the critical buckling stiffness. A seismic design flow chart of the intensity-reduced design method is proposed based on the numerical analyses and the Chinese Seismic Design Code of Buildings. The results indicate that the seismic intensity-reduced design for the proposed system is feasible. [ABSTRACT FROM AUTHOR]

This research innovatively presents a multi-parameter seismic fragility analysis methodology anchored on Blending ensemble learning tailored for the high-speed railway track-bridge (HSRTB) system. Leveraging ensemble machine learning models, a seismic demand model encapsulating multiple earthquake intensity measures (IMs) is formulated. The research progresses to deduce the mean seismic fragility representations for single, dual, and composite earthquake parameters. Key findings of this investigation underscore that the advanced methodology aligns well with the Monte Carlo (MC) fragility, signifying its robustness. Crucially, earthquake IM parameters, Sa(0.5) and Sa(0.3)_ASI, emerged as the optimal choices for singular and dual-parameter seismic fragility delineations. Further enriching this research, a composite parameter optimization technique rooted in multi-CPU genetic algorithms is proposed. This avant-garde method remarkably minimizes the fragility estimation error, emphasizing its unparalleled efficacy in enhancing the precision of fragility evaluations. [ABSTRACT FROM AUTHOR]

Seismic intensity measures (IMs) provide a link between the seismic hazard and the dynamic response of structures subjected to earthquake shaking. The spectral acceleration at the first and usually dominant vibration mode, Sa(T1), is a popular choice for building structures. Meanwhile, the IM selection for bridges is non-trivial since they do not typically possess a single dominant mode. Even for ordinary bridges with a dominant mode, the behavior can change significantly in each principal direction through the activation, or yielding, of its different components. This study examines the performance of a novel IM that incorporates ground motion directionality and structure non-linearity in this context: the nnth percentile of all rotation angles of the inelastic spectral displacement, Sdi,RotDnn. This evaluation is carried out within the context of an ordinary bridge structure and is compared with other conventional IMs used in regional risk assessment of bridges. The case study bridge utilized is a highway overcrossing located in California with two spans and a continuous prestressed reinforced concrete box girder deck section. A large ground motion set was selected from the NGA-West2 database, and incremental dynamic analysis was carried out on the structure to assess the IM performance to characterize collapse. The results indicate that Sdi,RotDnn performs very well compared to other IMs for the bridge structure and could be a prudent choice to characterize inelastic response of bridges with several possible mechanisms in different principal directions. Also, using the RotD50 definition, typically used in ground motion models, showed a 17.3% increase in efficiency compared to RotD100 definition typically used in engineering practice. [ABSTRACT FROM AUTHOR]

Seismic intensity measures (IMs) quantify the severity of ground motions and their impacts on structures. They play a vital role in many aspects of earthquake engineering. This paper proposes a novel method, namely the express iteration method (EIM), for constructing effective vector-valued IMs based on dozens of existing scalar ones given a specific engineering structure or a class of them. Taking advantage of the sophisticated while efficient mapping between scalar IMs and engineering demand parameters (EDPs) via a machine learning model, EIM iteratively eliminates less important scalar IMs from a pool of candidates to find the most effective combinations for a vector-valued IM and achieves superior computational efficiency by avoiding updating the nonlinear mapping during the process. Taking a base-isolated structure and its non-isolated counterpart for a demonstrating case study, the performance of the vector-valued IMs determined by EIM is compared with those by other existing methods in the literature for the task of selecting the most unfavorable ground motions. The results show that EIM prioritizes records with the largest peak inter-story drift PIDs and thus leads to the smallest subset that imposes most severe structural damage, while its computational cost was two orders of magnitude smaller as compared to the existing methods of similar effectiveness. Such superior performance can also be expected in all tasks that involve vector-valued IMs, including but not limited to multi-dimensional fragility analysis, incremental dynamic analysis, and real-time seismic damage prediction. [ABSTRACT FROM AUTHOR]

Recently, experimental studies on failure conditions of buildings equipped with curved surface sliding isolators have shown that when no displacement restraining elements are employed and the concave plates feature a flat rim, the inner slider can run on the edge of the sliding surfaces producing lateral displacement larger than the nominal isolator capacity. The over-stroke displacement capacity reduces the probability of seismic collapse of code-conforming base-isolated buildings for earthquake stronger than the design one. In order to quantify the benefit of the over-stroke displacement capacity of double concave curved surface slider (DCCSS) bearings on the seismic fragility of base isolated buildings, four case studies of six-storey reinforced concrete framed structures, consisting of new constructions and retrofit of existing structures located in high and medium hazard seismic sites, have been investigated in this paper. In all cases, two configurations of the isolation system have been considered, with end-stop displacement or with over-stroke displacement capacity. The seismic performance of the buildings has been investigated by multi-stripe nonlinear time-history analysis. The results of the nonlinear dynamic analysis at the collapse limit state have been compared with nonlinear static analysis in terms of maximum displacement and corresponding base shear. Fragility curves highlight a higher safety margin against collapse for seismic intensities beyond the design limit state of the isolation system with over-stroke capacity. [ABSTRACT FROM AUTHOR]

In this paper, a physical index for quantitatively evaluating the non-proportional damping characteristics is proposed. Additionally, a direct design approach applicable to composite isolated structures (consisting of an upper damping structure and a base isolation system) is proposed for performance analysis of practical three-dimensional non-proportional damped structures. Furthermore, the elastic–plastic behavior of the structure under acceleration excitation is considered to determine the structural damage and response, improving computational accuracy and providing better solutions for the analysis and design of composite isolated structures. Analysis studies have shown that under rare and extremely rare earthquake events, structures designed using the complex modal response spectrum method (CM-RSM) exhibit less damage compared to those designed using the forced decoupling response spectrum method (FD-RSM) compared to the results obtained using the complex modal response spectrum method. For the seismic performance study of non-proportional damped structures, it is recommended to use the complex modal response spectrum method. With an increasing earthquake intensity, the proportion of energy dissipation due to the nonlinear strain energy dissipation of a structure increases, and the proportion of energy dissipation due to the isolators and dampers in the damping energy portion decreases. [ABSTRACT FROM AUTHOR]

This paper aims at assessing the failure time of a 7‐story reinforced concrete (RC) frame in a post‐earthquake fire (PEF) event probabilistically. Cumulative distribution functions (CDF) of the studied frame's failure time in various seismic load intensities have been calculated and presented with the aid of Monte Carlo analysis. Seismic load intensity, failure time, and failure probability are three parameters that are correlated through probabilistic analysis. The effects of cracking, spalling, and residual deformations resulted from the seismic load are considered in the strength of structure against the fire load. Seismic load intensity, materials properties, gravity load, and geometry are considered as random variables and one probabilistic analysis has been carried out for each seismic load intensity. The results have illustrated that in low seismic load intensities, probabilistic values of failure time in a structure subjected to pure fire load are equal to the one exposed to PEF. With the increase of seismic load intensity, the effects of cracking, spalling, and residual deformations would lead to a decline in the strength of structural elements against PEF scenario. The failure time in 50% failure probability for Sa = 0.2 g, Sa = 1 g, and Sa = 2 g intensities has been calculated as 14,300, 12,200, and 5100 s, respectively. The analysis results have shown that in an unspecified seismic load intensity, the failure time of the 7‐story RC frame for the 50% occurrence probability is equal to 9750 s. [ABSTRACT FROM AUTHOR]

The mechanical performance of curved bridges under the action of an earthquake is complex. To obtain the influence of seismic parameters on the seismic response of curved girder bridges, this paper relies on a large slope small-radius curved steel box girder bridge (LSCGB) and selects seismic wave incidence angle, vertical component of ground motion, and site category as seismic parameters to carry out nonlinear time history analysis. Based on the analysis results of the case bridge, it is shown that the torsional vibration of the first 10 modes of LSCGB is significant, the modes are dispersed, and the contribution of high-order modes of vibration cannot be ignored. The most unfavorable seismic wave incidence angle is in the direction of 45°∼60° counterclockwise Angle from the central connection line of Pier No. 1 and Pier No. 4 of the bridge. The seismic response of the curved bridge components increases with the vertical seismic intensity, and the influence on displacement responses is more significant. The basic vibration period of curved girder bridges built on soft soil sites is extended by approximately 18.23%, and the seismic response of key components increases with the softening of the site soil. Therefore, when analyzing the seismic response of LSCGBs, the influence of vertical component of ground motion and site category should not be ignored. [ABSTRACT FROM AUTHOR]

Allowing the transitory attainment of bearing capacity of caisson foundations supporting bridge piers during strong seismic events can lead to substantial optimisation in their design and major cost savings. If the approach of capacity design is applied to geotechnical systems, the temporary triggering of plastic mechanisms may be permitted if the resulting permanent displacements are smaller than given threshold values. To validate this design approach, the seismic performance of caisson foundations was assessed through dynamic centrifuge testing on reduced-scale models. This paper presents the results of two tests in which a caisson–pier–deck system was embedded in a typical alluvial deposit and subjected to a series of earthquakes of different intensities. The caissons were founded on soft and very soft clay, to either avoid or induce the attainment of plastic soil behaviour under the same seismic inputs. It is shown that both yielding and failure of the layer of very soft clay limit inertial forces transmitted to the superstructure, validating the design approach and some useful empirical relations available in the literature. In contrast, inelastic soil behaviour implies accumulation of permanent rotation and settlement of the system, which must be carefully evaluated to check for fulfilment of performance requirements. [ABSTRACT FROM AUTHOR]

Timber-framed masonry structures are widely used around the world, and their seismic performance is generally poor. Most of them have not been seismically strengthened. In areas with high seismic fortification intensity, there are great potential safety hazards. And it is urgent to carry out effective seismic reinforcement. However, due to the complicated construction process of the existing reinforcement technology, the poor durability of the reinforcement materials, and the significant disturbance to the life of the original residents, an efficient single-story timber-framed masonry structure reinforcement technology suitable for comprehensive promotion and application has not been explored. In this paper, a fiber-reinforced cement mortar (FRCM) material was proposed. A 1/2 scale model of a single-story timber-framed masonry structure was taken as the research object. The method of strengthening a single-story timber-framed masonry structure with FRCM layer was adopted. And the shaking table test of the model before and after reinforcement was carried out in turn. The dynamic characteristics, failure modes, acceleration response and displacement response of the FRCM layer-strengthened structure were analyzed through comparisons of the two cases. The experimental results showed that the FRCM layer significantly improved the seismic performance of the seismic-damaged single-story timber-framed masonry structures. The X- and Y-direction natural frequencies of the model structure were increased by 31.30% and 30.22%, respectively, after the structure was strengthened with FRCM. During a rare eight-degree earthquake, the inter-story displacement angles in the X- and Y-direction of the unreinforced model reached 1/98 and 1/577, respectively, and the structure was destroyed, while the inter-story displacement angle of the FRCM-reinforced model was only 1/2 of that the unreinforced model. During a rare nine-degree earthquake, the X-direction inter-story displacement angle of the model strengthened with FRCM reached 1/78 and the Y-direction inter-story displacement angle reached 1/178. At this time, the reinforced model structure was destroyed, but there was no collapse of the structural components, which met the seismic design objectives of "operational under the design minor seismic intensity, repairable damage under the design seismic precautionary intensity, and collapse prevention under the design rare seismic intensity", which proved that the FRCM layer was an effective and feasible way to strengthen the existing single-story wood-masonry rural building. [ABSTRACT FROM AUTHOR]

The accurate assessment of soil conditions is crucial for ensuring the seismic safety of buildings and structures. The existing classification of soils in the building code of Uzbekistan has several drawbacks that affect the accuracy of the input parameters of soil properties, the determination of the seismic intensity of the ground, and the underestimation of external environmental factors that affect seismic intensity. In response to these shortcomings, this paper presents the results of long-term engineering geological, macroseismic, and geophysical studies conducted to assess the influence of ground conditions on seismic intensity parameters. Based on the findings, a new classification of soils according to seismic properties is proposed. The classification system considers the unique characteristics of each soil type and provides a more accurate representation of their seismic properties. The proposed classification system is expected to provide valuable insights for seismic hazard assessment and earthquake-resistant design of structures. [ABSTRACT FROM AUTHOR]

In this study, we calculated the seismic intensity for the Baikal–Olekma section of the Baikal–Amur Railway based on data on seismicity on the northeastern flank of the Baikal Rift Zone in 1985–2021. During the analysis of earthquakes with an epicentral intensity higher than 4 (1484 events), we selected 270 earthquakes with Ms = 2.1–6.6, whose calculated intensity exceeded 4 points directly on the railway track from the total number of the recorded seismic events (more than 150 000 earthquakes with M ≥ 1.0). The highest intensity values (8–9) were obtained for large earthquakes close to the Baikal–Olekma section of the Baikal–Amur Railway (Δ < 10 km, Ms = 6.1–6.2). A recurrence interval of such seismic events along the considered section of the railway is 20–60 years. The data are agree well with the macroseismic data available, which confirms the correctness of the results. At the same time, macroseismic effects from strong (Ms ≥ 6.6) but remote earthquakes (Δ = 360–1000 km) were found to have no significant impact on the Baikal–Olekma section of the Baikal–Amur Railway. The calculated values of intensity and recurrence intervals of earthquakes should be taken into account when designing, constructing, and operating industrial and civil infrastructure within the study area. [ABSTRACT FROM AUTHOR]

The 2018, Mw 6.6 Hokkaido Eastern Iburi earthquake in Japan triggered over 10,000 landsliding in an area spanning about 500 km2, altering the local topography and leading to the accumulation of loose deposits on hillslopes and in valleys. However, a comprehensive post-seismic landslide inventory and an assessment of topographic changes are lacking, hindering a quantitative hazard assessment. Additionally, the extent of vegetation recovery in areas affected by coseismic landslides, a key indicator of post-seismic debris flow hazard, has not been evaluated. Here, we utilize high-resolution digital elevation models and multi-temporal satellite imagery to analyze topographic changes and vegetation dynamics in the earthquake's epicentral area (seismic intensity >5.5). We observe that the event roughened the overall gentle topography of the region and made the slopes steeper. Owing to the absence of significant rainstorms and snowmelt post 2018, only a few debris remobilizations (60) and new landslides (80) have occurred in the affected region. Moreover, we noticed a slow vegetation recovery in the post-seismic phase, suggesting that the likelihood of debris flows and gully erosion remains elevated, highlighting the need for continued monitoring and assessment. [ABSTRACT FROM AUTHOR]

Interaction between masonry infill walls (MIWs) and a main structural system can impact the overall structural performance. However, there is no test to investigate the impact of MIWs on self-centering prestressed concrete (SCPC) frames, nor has there been a probabilistic performance evaluation considering the coupling effects of peak interstory drift ratio (PIDR) and residual interstory drift ratio (RIDR). This study compares the seismic performance of SCPC frames with and without MIWs through quasi-static tests and seismic risk assessment under mainshock–aftershock (MSAS) sequences. To begin, quasi-static tests on one-story SCPC frames with and without MIWs are performed to assess their seismic performance. A numerical simulation method for the SCPC frame with MIWs is then proposed and validated. Following that, the seismic performance of four multistory SCPC frames with and without MIWs is investigated under MSAS sequences at the maximum considered earthquake level. Finally, the seismic vulnerability assessment, considering the coupling effect of PIDR and RIDR under MSAS sequences, is conducted. The results indicate that cracks on the MIW present diagonal stepped cracks, and the MIW does not cause damage to the SCPC frame. When the MIW is damaged, the RIDR of the SCPC-MIW frame increases significantly; when the crack development is stable, the RIDR increases slowly as the interstory drift increases but remains at a very low level. Besides, when the MIW is damaged, an obvious deformation concentration effect occurs on the SCPC-MIW frame. The SCPC-MIW frame has a lower probability of exceeding the immediate occupancy level P(IO) than the SCPC frame, but it has a higher probability of exceeding the repairable level P(RE) when the seismic intensity is relatively small. Overall, the P(IO) and P(RE) of the SCPC and SCPC-MIW frames are higher under MSAS sequences than under MS-only sequences, except for the SCPC25 frame. [ABSTRACT FROM AUTHOR]

A new scenario-based method is proposed to determine the performance range of structural systems. The advantage of this method is using inter-storey drift as a damage index, while exploiting local damage indices of the main structural members without the need for detailed analytical models and computationally expensive non-linear dynamic analyses. A new damage function is proposed by linking the local (plastic hinge rotations) and global (inter-storey drifts) damage levels. The accuracy of the proposed function is evaluated and compared with the indices in ASCE41–06, ATC-13, and HAZUS for a set of steel moment-resisting frames subjected to earthquakes of varying intensities. [ABSTRACT FROM AUTHOR]

A new damping control method for the adjacent liquid storage tanks (LSTs) based on vibration barrier (ViBa) is proposed. Considering liquid-solid-soil coupling and structure-soil-structure interaction, a three-dimensional numerical calculation model is established by ADINA. The seismic control effect of ViBa is investigated, and parametric analysis is carried out. The results show that ViBa has a significant control effect on seismic responses and wave height, and the reduction factor of base shear force reaches the maximum value of 49.26%. The larger the seismic intensity, the liquid storage height and the height-radius ratio, the larger the reduction factor of the ViBa. [ABSTRACT FROM AUTHOR]

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]

Previous earthquake events indicate that pile foundations in liquefiable soils are vulnerable to damage due to the coupling of inertial and kinematic effects. Inclined piles are widely applied in structures located in liquefiable soils, but few investigations of the coupling of the superstructure–pile inertial and soil–pile kinematic effects have been conducted. To address this gap, this study adopted a three-dimensional (3D) numerical model to investigate the coupling of inertial and kinematic effects in pile foundations with different inclination angles. The pile head bending moment was employed to represent the pile response, while the soil surface displacement and structure acceleration were utilized to quantify the kinematic and inertial effects. The role of the inclination angle on the interactions between inertial and kinematic effects is herein considered for pile groups. In particular, the inertial effect significantly influences the behavior of pile groups with larger inclination angles, whereas the kinematic effect predominates the pile head moment in vertical pile groups. In this paper, the influence of the pile inclination angle, superstructure configuration, and earthquake intensity on the interactions was investigated. The principal findings revealed that the kinematic effect dominates in the vertical pile group irrespective of the properties of the superstructure, while the inertial effect plays a significant role in the response of the inclined pile groups, especially for superstructures with considerable heights. Practical Applications: Inclined piles are vulnerable to damage due to the interaction of inertial and kinematic effects during earthquakes. This study conducted a series of three-dimensional (3D) finite-element simulations to investigate the interaction of inertial and kinematic effects in pile foundations with different inclination angles. The influence of pile inclination angle, superstructure height, and earthquake characteristics was investigated. In current practices, various codes and pseudostatic methods have been adopted to sum a percentage of the inertia-induced bending moment and another percentage of the kinematic-induced bending moment. This study indicates that under certain conditions, the simple summing of the bending moment induced by the inertial and kinematic effects could be inaccurate. The present study identified several factors that influence the interaction of inertial and kinematic effects on piles with different inclination angles. The inclined piles in liquefied soil, especially for supporting tall and heavy superstructure, attention should be given to the influence of inertial effect on the pile head bending moment. [ABSTRACT FROM AUTHOR]

Segmental tunnel is widely adopted in the urban transportation system, thereby its seismic resilience is a cornerstone for resilient cities. The segmental tunnel is an assembly of reinforced concrete segments, bolts, gaskets, gaps, etc., and exhibits highly nonlinear behavior when subjected to external loadings. Yet, in practice, its seismic response is generally estimated via a holistic modeling approach where the segmental tunnel is represented by a homogeneous beam or shell element with equivalent stiffness. Here, a multi-contact joint-based model is developed for a segmental tunnel, incorporating the nonlinearities embedded in the assembly with acceptable computational costs. The reinforced concrete segment is represented as the displacement-based fiber beam element, whereas the complex interaction among the configurations of the joint, i.e. bolt, gasket, and contacting concrete, is modeled via the zero-length section element. The proposed model’s accuracy is validated via a series of experimental data under three loading scenarios. A sensitivity analysis demonstrates that the mechanical response of segmental tunnels highly relies on the assembly configurations. The proposed model is implemented to investigate the seismic response of a typical segmental tunnel under various ground motions, demonstrating its applicability in seismic safety assessments, particularly in capturing the nonlinear response of segmental tunnels under high-intensity earthquakes. [ABSTRACT FROM AUTHOR]

The seismic resilience of cities plays a crucial role in achieving the United Nations Sustainability Development Goal. However, despite the occurrence of elevator passenger entrapment in numerous earthquakes, there is a notable lack of studies addressing this sophisticated issue. This study aims to bridge this gap by proposing a novel urban risk assessment model designed to evaluate city‐scale earthquake‐induced elevator passenger entrapment. The model integrates big data and physics‐based approaches. A novel mapping method was developed to estimate city‐scale elevator traffic level based on population heatmap data and deep learning. A process‐based parallel computing scheme was designed to accelerate the assessment. The applicability was demonstrated based on a real‐world urban area comprising 619 buildings. The findings reveal that as the time of the earthquake varies, the risk exhibits significant fluctuations. Additionally, this study highlights that a simplistic correspondence between seismic intensity and passenger entrapment risk can lead to erroneous estimations. [ABSTRACT FROM AUTHOR]

Compelling evidence has shown that geomagnetic disturbances in vertical intensity polarization before great earthquakes are promising precursors across diverse rupture conditions. However, the geomagnetic vertical intensity polarization method uses the spectrum of smooth signals, and the anomalous waveforms of seismic electromagnetic radiation, which are basically nonstationary, have not been adequately considered. By combining pulse amplitude analysis and an experimental study of the cumulative frequency of anomalies, we found that the pulse amplitudes before the 2022 Luding M6.8 earthquake show characteristics of multiple synchronous anomalies, with the highest (or higher) values occurring during the analyzed period. Similar synchronous anomalies were observed before the 2021 Yangbi M6.4 earthquake, the 2022 Lushan M6.1 earthquake and the 2022 Malcolm M6.0 earthquake, and these anomalies indicate migration from the periphery toward the epicenters over time. The synchronous changes are in line with the recognition of previous geomagnetic anomalies with characteristics of high values before an earthquake and gradual recovery after the earthquake. Our study suggests that the pulse amplitude is effective for extracting anomalies in geomagnetic vertical intensity polarization, especially in the presence of nonstationary signals when utilizing observations from multiple station arrays. Our findings highlight the importance of incorporating pulse amplitude analysis into earthquake prediction research on geomagnetic disturbances. [ABSTRACT FROM AUTHOR]

To estimate the connectivity of a road network, it is crucial to evaluate the correlation of hazard intensities among individual bridge locations since the probability of multiple bridges being damaged simultaneously depends on the degree of this correlation. However, research on connectivity assessment of bridge networks considering spatial correlations associated with flood intensities is scarce in the literature. When quantifying the spatial correlation of flood intensities, modeling based on the stream distance rather than the Euclidean distance is required, taking into account that river flow is restricted only within the stream network. To achieve this purpose, a novel methodology is proposed to evaluate the spatial correlation of a stream network based on a geostatistical linear model and stream network covariance models. In addition, this study considers the spatial correlation of seismic hazard intensity. With the proposed method, it is possible to identify which bridges play an important role in ensuring the connectivity of the road network under multiple hazards, i.e. flood and seismic. As an illustrative example, the proposed method is applied to a hypothetical bridge network in Kumamoto Prefecture, Japan. The results demonstrate that improved network connectivity can be achieved by implementing a relevant retrofitting strategy for important bridges. [ABSTRACT FROM AUTHOR]

Seismic intensity measures (IMs) can directly affect the seismic risk assessment and the response characteristics of underground structures, especially when considering the key variable of burial depth. This means that the optimal seismic IMs must be selected to match the underground structure under different buried depth conditions. In the field of seismic engineering design, peak ground acceleration (PGA) is widely recognized as the optimal IM, especially in the seismic design code for aboveground structures. However, for the seismic evaluation of underground structures, the applicability and effectiveness still face certain doubts and discussions. In addition, the adverse effects of earthquakes on tunnels in soft soil are particularly prominent. This study aims to determine the optimal IMs applicable to different burial depths for horseshoe-shaped tunnels in soft soil using a nonlinear dynamic time history analysis method, and based on this, establish the seismic fragility curves that can accurately predict the probability of tunnel damage. The nonlinear finite element analysis model for the soil–tunnel interaction system was established. The effects of different burial depths on damage to horseshoe-shaped tunnels in soft soil were systematically studied. By adopting the incremental dynamic analysis (IDA) method and assessing the correlation, efficiency, practicality, and proficiency of the potential IMs, the optimal IMs were determined. The analysis indicates that PGA emerges as the optimal IM for shallow tunnels, whereas peak ground velocity (PGV) stands as the optimal IM for medium-depth tunnels. Furthermore, for deep tunnels, velocity spectral intensity (VSI) emerges as the optimal IM. Finally, the seismic fragility curves for horseshoe-shaped tunnels in soft soil were built. The proposed fragility curves can provide a quantitative tool for evaluating seismic disaster risk, and are of great significance for improving the overall seismic resistance and disaster resilience of society. [ABSTRACT FROM AUTHOR]

One of the primary concerns in the field of seismic risk assessment for underground structures is establishing an accurate connection between seismic intensity and structural responses. The objective of this work is to conduct a rational support vector machine (SVM) model for generating mass data and improved fragility curves of cross-fault hydraulic tunnels (CFHTs). The results highlight that the 900 sets, multiple earthquake intensity measures, and cubic polynomial kernel function of the SVM model can improve reliability in evaluating structural performance. Additionally, the improved Cloud analysis method is more suitable for seismic performance than the typical Cloud analysis. [ABSTRACT FROM AUTHOR]

The effectiveness of the tuned mass damper inerter (TMDI) in reducing the vibration of building structures under site-specific earthquake excitation is investigated. The site is Guwahati, Assam, which lies in the most severe seismic intensity zone in India. In this paper, the optimization of the TMDI design parameters is carried out for the site-specific input derived for the building site by a modulated Clough-Penzien (C-P) spectrum fitted to the power spectral density function obtained from a strong motion model of the site. All possible topologies of the TMDI, with one terminal of the inerter being connected to the damper mass attached to the top storey of the example buildings, and the other terminal being connected to any other floor, are investigated. The structure-TMDI system is analyzed both in the frequency-domain and in the time-domain. A numerical study is conducted with two example building structures. Optimization of design parameters of the TMDI is carried out using the technique of simulated annealing in the frequency-domain using the site-specific modulated Clough-Penzien spectrum as input. The performance of the optimal TMDI cases is evaluated by subjecting the example structures to 10 site-specific synthetically generated accelerograms. Results indicate that the TMDI is superior to the TMD for all topologies of the TMDI in case of the 3-storieed structure; and for topologies of the TMDI in which the inerter spans more than 4 floors for the 8-storied structure, with improved reductions in top-floor displacement, acceleration, and stroke length. [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]

This study aims to investigate the adverse effects of near-fault ground motions on the long-term development of high-speed railways. In this paper, the ground motions are analyzed based on the Train–Track–Bridge Coupling Braking System (TTBCBS) which has been validated during earthquakes. The effects of earthquakes on the whole system are discussed in depth, focusing on the random nature of earthquakes, the impulsive character of near-fault earthquakes and the effects of different initial speeds on the system behavior. The results show that under random earthquakes, the probability of train derailment gradually increases with the increase of peak ground acceleration (PGA) of earthquakes. When the PGA exceeds 0.2 g, the train is highly susceptible to derailment and the bridge itself may incur damage. When analyzing the nature of pulses of near-fault ground motions, it was found that the responses induced by class B and class C pulses are significantly similar. Meanwhile, the calculated values of derailment coefficients are basically the same when the PGA of class A pulse wave is at 0 g and 0.1 g. This suggests that train braking somewhat mitigates the response induced by near-fault ground motions. Furthermore, the value of improved spectral intensity (SI) for the running safety during earthquakes indicates that the increase in seismic intensity is detrimental to the system. In terms of the effect of train initial speeds on the system during earthquakes, it is observed that the system response reaches the lowest point when the train speed is 250 km/h, which is more favorable to the smooth deceleration of the train. When the train speed is 400 km/h, the system response reaches its maximum value. These research findings provide crucial insights and guidance for seismic safety design and management of high-speed railways. [ABSTRACT FROM AUTHOR]

The article discusses the Neodeterministic (NDSHA) approach to seismic hazard assessment, which aims to prevent seismic disasters rather than simply addressing their consequences. The NDSHA method takes into account the tensor nature of earthquake ground motions and has been proven reliable through experiments conducted over the past 25 years. The article also highlights the organization of the book "Earthquakes and Sustainable Infrastructure- Neodeterministic (NDSHA) Approach Guarantees Prevention Rather Than Cure," which compiles developments in the NDSHA approach and its application in various countries and regions. The book covers topics such as hazard analysis, earthquake forecasting, site response evaluation, and the seismic performance of infrastructure. This book provides a comprehensive exploration of seismic hazard assessment, focusing on the gap between engineering principles and the needs of seismologists, engineering seismologists, and policymakers. It emphasizes the importance of designing infrastructure to withstand future earthquakes and prevent damage. [Extracted from the article]

An earthquake of Mw = 7.0 occurred on October 30, 2020, in the Aegean Sea near Samos Island, which caused severe structural damage in Bayraklı, Izmir (Türkiye), located around 70 km from the epicenter. To investigate the source, path, and site effects, ground motions recorded in Western Anatolia are simulated using the stochastic finite-fault method based on a dynamic corner frequency approach. The input model parameters are calibrated using the recorded motions at selected 10 stations within an epicentral distance of less than 100 km. The soil amplifications are modeled using horizontal-to-vertical spectral ratios and generic amplification factors. At most stations, including a few within Izmir Bay, amplitudes and frequency contents are modeled closely. Minor discrepancies within particular frequency bands can be attributed to insufficient representation of the local site effects. Finally, distributions of observed and simulated felt intensities are found to be consistent. [ABSTRACT FROM AUTHOR]

A devastating earthquake with moment magnitude 7.5 occurred in the Noto Peninsula in central Japan on 1 January 2024. We estimate the rupture evolution of this earthquake from teleseismic P‐wave data using the potency‐density tensor inversion method, which provides information on the spatiotemporal slip distribution including fault orientations. The results show a long and quiet initial rupture phase that overlaps with regions of preceding earthquake swarms and associated aseismic deformation. The following three major rupture episodes evolve on segmented, differently oriented faults bounded by the initial rupture region. The irregular initial rupture process followed by the multi‐scale rupture growth is considered to be controlled by the preceding seismic and aseismic processes and the geometric complexity of the fault system. Such a discrete rupture scenario, including the triggering of an isolated fault rupture, adds critical inputs on the assessment of strong ground motion and associated damages for future earthquakes. Plain Language Summary: On 1 January 2024, a moment magnitude 7.5 earthquake occurred in the northern Noto Peninsula, Japan. The strong ground motion and tsunami associated with the earthquake caused severe damage to buildings and infrastructure, resulting in at least 245 causalities in the affected areas. The Noto Peninsula is affected by northwest‐southeast compression, and active reverse faults are known along the northern coast of the peninsula and its offshore region. Before the 2024 earthquake, the source region experienced long‐lasting earthquake swarm activity, which is a set of seismic events without an obvious mainshock‐aftershock pattern. Our seismological analysis found that there was a 10‐s‐long initial rupture episode around the hypocenter that overlapped with the earthquake swarm region. The initial rupture was followed by a series of three different rupture episodes on differently oriented fault segments. This earthquake highlights a multi‐scale rupture growth across a segmented fault network after a very quiet initial rupture process that was controlled by the preceding earthquake swarms and associated aseismic deformation related to fluid injection from depth. The rupture process advances our understanding of earthquake source physics and can lead to a better assessment of future earthquake hazards. Key Points: The 2024 Mw 7.5 Noto Peninsula earthquake involves a multi‐segmented rupture sequence on differently oriented faultsThe long and quiet initial rupture domain coincides with the preceding earthquake swarm regionFluid‐induced earthquake swarms and a segmented fault network control the complex earthquake rupture growth [ABSTRACT FROM AUTHOR]

An earthquake early-warning system (EEWS) is an indispensable tool for mitigating loss of life caused by earthquakes. The ability to rapidly assess the severity of an earthquake is crucial for effectively managing earthquake disasters and implementing successful risk-reduction strategies. In this regard, the utilization of an Internet of Things (IoT) network enables the real-time transmission of on-site intensity measurements. This paper introduces a novel approach based on machine-learning (ML) techniques to accurately and promptly determine earthquake intensity by analyzing the seismic activity 2 s after the onset of the p-wave. The proposed model, referred to as 2S1C1S, leverages data from a single station and a single component to evaluate earthquake intensity. The dataset employed in this study, named "INSTANCE," comprises data from the Italian National Seismic Network (INSN) via hundreds of stations. The model has been trained on a substantial dataset of 50,000 instances, which corresponds to 150,000 seismic windows of 2 s each, encompassing 3C. By effectively capturing key features from the waveform traces, the proposed model provides a reliable estimation of earthquake intensity, achieving an impressive accuracy rate of 99.05% in forecasting based on any single component from the 3C. The 2S1C1S model can be seamlessly integrated into a centralized IoT system, enabling the swift transmission of alerts to the relevant authorities for prompt response and action. Additionally, a comprehensive comparison is conducted between the results obtained from the 2S1C1S method and those derived from the conventional manual solution method, which is considered the benchmark. The experimental results demonstrate that the proposed 2S1C1S model, employing extreme gradient boosting (XGB), surpasses several ML benchmarks in accurately determining earthquake intensity, thus highlighting the effectiveness of this methodology for earthquake early-warning systems (EEWSs). [ABSTRACT FROM AUTHOR]

The new generation of China Railway Track System III (CRTS III) ballastless track structure has been found vulnerable under high-level earthquakes. However, the seismic characteristics and the damage mechanism had not been well studied. In this paper, a 4-span high-speed railway (HSR) simply supported bridge-track system model is established to investigate the seismic response and damage mechanism of the bridge-CRTS III slab ballastless track system under transverse earthquakes by nonlinear history analysis. In accordance with the results, the piers have a good seismic performance under high-level earthquake (0.57 g). The non-uniform vibration of unequal-height piers results millimeter-level inconsistent displacements between the girders. The fixed bearing is vulnerable under the earthquakes with PGA of 0.3 g and 0.57 g, indicating that the seismic design of fixed bearing should be optimized to enhance the seismic resistance under high-intensity earthquake. After the damage of fixed bearing, the friction is not enough to pull the girders to vibrate together with piers which leads the sliding of girders. The sliding of girder exacerbates the non-uniform displacements of girders and roadbed. The non-uniform vibration and residual slips of girders lead deformation of the rail, especially forming turning angles at the girder joints which may impact the safety of train operation. [ABSTRACT FROM AUTHOR]

Indonesia is a country with a high potential for disasters such as earthquakes, which usually cause changes in the shape/position of the earth's surface (deformation). The Cianjur area has a seismic vulnerability level value based on maximum ground acceleration, maximum intensity and earthquake return period. On Monday, November 21, 2022 at 13.21 WIB there was an earthquake with a magnitude of 5.6 M in the Cianjur area of West Java based on BMKG data, until November 22, 2022 there were 140 aftershocks with magnitudes of 1.2-4.2 and an average depth of approximately 10 km. As a result, causing subsidence, the purpose of this study is to determine the magnitude of subsidence in landslides due to the 2022 Cianjur earthquake using the DInSAR method. Vertical land subsidence (displacement data) due to the earthquake from DInSAR observations on displacement data, which ranged up to -101mm vertically with two soil types andosol and cambisol Overlay analysis of soil type and displacement data showed the highest area of displacement, found a match based on information circulating that Cugenang Sub-district is the most severely affected area (the existence of a new fault "Cugenang"). [ABSTRACT FROM AUTHOR]

Pounding between adjacent structures subjected to earthquake actions can cause significant damage. Due to the many uncertainties inherent to the seismic input and the impact phenomenon, a probabilistic assessment of the occurrence of seismic pounding and of its consequences on the structural performance is necessary. This work analyzes the problem of pounding by considering a single-degree-of-freedom benchmark system surrounded by rigid boundaries and subjected to a stochastic earthquake input. Although simplified, the model is representative of several realistic configurations, such as base-isolated systems surrounded by moat walls or bridge decks near the bridge abutments. The problem is cast in non-dimensional form and a parametric study is carried out to evaluate the influence of the identified non-dimensional input parameters on the statistics of the response. A probabilistic demand model is developed for the impact forces via non-linear regression, with the demand expressed as a function of the identified non-dimensional parameters. This model provides an estimate of median pounding force and of its dispersion given the seismic intensity of the input. Finally, global sensitivity analysis is used to rank the model parameters in terms of their influence on the system performance. [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]

Many examples of earthquake damage show that liquefied lateral spreading is the main cause of pile foundation failure. Rigid drainage piles (RDPs), with two drainage grooves and plastic drainage plates, are a new type of liquefaction-resistant pile that can take into account the bearing capacity and drainage function. A series of 1g shaking table tests was carried out to analyse the seismic response of an RDP–superstructure–quay wall system subjected to lateral spreading. Three levels of earthquake intensities – small (peak ground acceleration (PGA) of 0.05g), moderate (PGA = 0.1g) and large (PGA = 0.2g) – were investigated. The improvement in the anti-liquefaction performance using RDPs was analysed. The influences of far-field (FF) and near-field (NF) ground motions were also examined. The experimental results showed that RDPs can effectively reduce the liquefaction degree and the horizontal flow of the sand stratum. In addition, the internal force and displacement of the superstructure built on RDPs were small. The seismic response due to NF ground motion was found to be more significant than that of the FF ground motion, but the effects of FF ground motion cannot be disregarded. The results of the tests could provide useful information for the design of RDP groups in a typical pile–superstructure–quay wall system. [ABSTRACT FROM AUTHOR]

To systematically analyze the damage caused by bedrock and overburden layer slope under seismic action, a set of large-scale shaking table test was designed and completed. Interpolation of the acceleration amplification coefficient, Hilbert–Huang transform and transfer function was adopted. The damage mechanisms of the bedrock and overburden layer slopes under seismic action are systematically summarized in terms of slope displacement, acceleration field, vibration amplitude, energy, vibration frequency, and damage level. The results show a significant acceleration amplification effect within the slope under seismic action and a localized amplification effect at the top and trailing edges of the slope. With an increase in the input seismic intensity, the difference in the vibration amplitude between the overburden layer and bedrock increased, low-frequency energy of the overburden layer was higher than that of the bedrock, and the vibration frequency of the overburden layer was smaller than that of the bedrock. These differences cause the interface to experience cyclic loading continuously, resulting in the damage degree of the overburden layer at the interface being larger than that of the bedrock, reduction of the shear strength, and eventual formation of landslides. The displacement in the middle of the overburden is always greater than that at the top. Therefore, under the action of an earthquake and gravity, the damage mode of the bedrock and overburden layer slope is such that the leading edge of the critical part pulls and slides at the trailing edge, and multiple tensile cracks are formed on the slope surface. [ABSTRACT FROM AUTHOR]

Earthquake-triggered landslides (ETLs) feature large quantities, extensive distributions, and enormous losses to human lives and critical infrastructures. Near-real spatial prediction of ETLs can rapidly predict the locations of coseismic landslides just after a violent earthquake and is a vital technical support for emergency response. However, near-real prediction of ETLs has always been a great challenge with relatively low accuracy. This work proposes an ensemble prediction model of EnPr by integrating machine learning tree models and a deep learning convolutional neural network. EnPr exhibits relatively strong prediction and generalization performance and achieves relatively accurate prediction of ETLs. Six great seismic events occurring from 2008 to 2022 on the southeastern margin of the Tibetan Plateau are selected to conduct ETL prediction. In a chronological order, the 2008 Ms 8.0 Wenchuan, 2010 Ms 7.1 Yushu, 2013 Ms 7.0 Lushan, and 2014 Ms 6.5 Ludian earthquakes are employed for model training and learning. The 2017 Ms 7.0 Jiuzhaigou and 2022 Ms 6.1 Lushan earthquakes are adopted for ETL prediction. The prediction accuracy merits of ACC and AUC attain 91.28% and 0.85, respectively, for the Jiuzhaigou earthquake. The values of ACC and AUC achieve 93.78% and 0.88, respectively, for the Lushan earthquake. The proposed EnPr algorithm outperforms the algorithms of XGBoost, random forest (RF), extremely randomized trees (ET), convolutional neural network (CNN), and Transformer. Moreover, this work reveals that seismic intensity, high and steep relief, pre-seismic fault tectonics, and pre-earthquake road construction have played significant roles in coseismic landslide occurrence and distribution. The EnPr model uses globally accessible open datasets and can therefore be used worldwide for new large seismic events in the future. [ABSTRACT FROM AUTHOR]

The research attempts to provide a method for evaluating the susceptibility of heritage buildings and potential damage considering local site effects, using as a case study an urban sector situated in Horta, Faial, Azores, Portugal. The physical vulnerability of the investigated structures was appraised using an index-based method devised for structural masonry aggregates to emphasize their likelihood of seismic damage. As a result, a damage scenario based on real accelerograms collected after the 1998 Azores seismic event was developed by using a reliable seismic intensity prediction equation. In addition, the soil amplification, which increases the extent of seismic damage to the examined structures, is assessed by varying the soil conditions using EN 1998–1 Code. Thus, this research emphasises the ground impact in forecasting the expected damage scenarios, enabling optimised risk mitigation strategies in urban settings. [ABSTRACT FROM AUTHOR]

Smartphone location data provide the most direct field disaster distribution data with low cost and high coverage. The large-scale continuous sampling of mobile device location data provides a new way to estimate the distribution of disasters with high temporal–spatial resolution. On September 5, 2022, a magnitude 6.8 earthquake struck Luding County, Sichuan Province, China. We quantitatively analyzed the Ms 6.8 earthquake from both temporal and geographic dimensions by combining 1,806,100 smartphone location records and 4,856 spatial grid locations collected through communication big data with the smartphone data under 24-hour continuous positioning. In this study, the deviation of multidimensional mobile terminal location data is estimated, and a methodology to estimate the distribution of out-of-service communication base stations in the disaster area by excluding micro error data users is explored. Finally, the mathematical relationship between the seismic intensity and the corresponding out-of-service rate of communication base stations is established, which provides a new technical concept and means for the rapid assessment of post-earthquake disaster distribution. [ABSTRACT FROM AUTHOR]

The Non-homogeneous Poisson Process, with time-dependent intensity functions, is commonly used to model the scenario of counting the number of events that appear to occur in a given time interval. The identification of the process relies on the functional form of the intensity function, which can be difficult to determine. In this paper, a Non-Homogenous Poisson Process model is proposed to predict the intensity function for the number of earthquake occurrences in Iraq; the constructed model allows anticipating the number of earthquakes that occur at any time interval with a specific time length. Then, to estimate the model parameters, the data obtained from the annual reports of the Iraqi Meteorological Organization and Seismology (IMOS) from January 1st 2018 to April 30th 2023 are used. Moreover, a simulation study is conducted and a new algorithm is introduced to show the performance and applicability of the proposed model. [ABSTRACT FROM AUTHOR]

In recent decades, research on renewable energy has been boosted by the emerging awareness of energy security and climate change and their consequences, such as the global cost of adapting to the climate impacts. Both onshore and offshore wind turbine farms have been considered as one of the main alternatives to fossil fuels. Their development currently involves seismic-prone areas, such as the Californian coastline and East Asia, where the risk of soil liquefaction is significant. Onshore wind turbines (OWTs) typically are founded on shallow rafts. Their operation can be affected strongly by the simultaneous presence of intense earthquakes and wind thrust, which may cause remarkable permanent tilting and loss of serviceability. In these conditions, accurate evaluation of the seismic performance of these structures requires the development of well-validated numerical tools capable of capturing the cyclic soil behavior and the build-up and contextual dissipation of seismic-induced pore-water pressures. In this paper, a numerical model developed in OpenSees, calibrated against the results of dynamic centrifuge tests, was used to evaluate the influence of some ground motion intensity Measures of the seismic behavior of OWTs included the amplitude, frequency content, strong-motion duration, and Arias intensity (energy content) of the earthquake, together with the effect of a coseismal wind thrust, which is not well explored in the literature. The seismic performance of an OWT was assessed in terms of peak and permanent settlement and tilting, the latter of which was compared with the threshold of 0.5° typically adopted in practice. [ABSTRACT FROM AUTHOR]

In this work, a total of nine ultra-high performance concrete (UHPC) filled steel tubular columns (UHPCFSTs) were fabricated and tested under cyclic loading. The results indicated that UHPCFSTs mainly exhibited flexural failure mode, compression-flexure failure mode and welding line fracture, and it changed from flexural failure mode to compression-flexure failure mode when the axial compression ratios exceeded 0.3. The elastic and ultimate drift ratios of UHPCFSTs were within the ranges of 1.37–2.05% and 2.38–4.32%, respectively, and the equivalent viscous damping coefficients were within the range of 0.197–0.358 when they failed, UHPCFSTs could sever as good choices in high seismic intensity areas. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard assessments (PSHAs) provide the scientific basis for building codes to reduce damage from earthquakes. Despite their substantial impact, little is known about how well PSHA predicts actual shaking. Recent PSHA for California, Japan, Italy, Nepal, and France appear to consistently overpredict historically observed earthquake shaking intensities. Numerical simulations show that observed shaking is equally likely to be above or below predictions. This result from independently developed models and datasets in different countries and tectonic settings indicates possible systematic bias in the hazard models, the observations, or both. Analysis of possible causes shows that much of the discrepancy is due to a subtle and rarely considered issue: the conversion equations used in comparing the models--which forecast shaking as peak ground acceleration or velocity--and observations--parameterizations of qualitative shaking reports. Historical shaking reports fill a crucial data gap, but more research is warranted on how qualitative observations relate to instrumental shaking measures for earthquakes. [ABSTRACT FROM AUTHOR]

The Newmark displacement (ND) method, which reproduces the interactions between waves, solids, and fluids during an earthquake, has experienced numerous modifications. We compare the performances of a traditional and a modified version of the ND method through the analysis of co-seismic landslides triggered by the 2022 Ms 6.8 Luding earthquake (Sichuan, China). We implemented 23 ND scenarios with each equation, assuming different landslide depths, as well as various soil-rock geomechanical properties derived from previous studies in regions of similar lithology. These scenarios allowed verifying the presence or absence of such landslides and predict the likely occurrence locations. We evaluated the topographic and slope aspect amplification effects on both equations. The oldest equation has a better landslide predictive ability, as it considers both slope stability and earthquake intensity. Contrarily, the newer version of the ND method has a greater emphasis on slope stability compared to the earthquake intensity and hence tends to give high ND values only when the critical acceleration is weak. The topographic amplification does not improve the predictive capacity of these equations, most likely because few or no massive landslides were triggered from mountain peaks. This approach allows structural, focal mechanism, and site effects to be considered when designing ND models, which could help to explain and predict new landslide distribution patterns such as the abundance of landslides on the NE, E, S, and SE-facing slopes observed in the Luding case. [ABSTRACT FROM AUTHOR]