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Peak ground acceleration (PGA) is one of the critical factors that affect the determination of earthquake intensity. PGA is generally utilized to describe ground motion in a particular zone and is able to efficiently predict the parameters of site ground motion for the design of engineering structures. Therefore, novel models are developed to forecast PGA in the case of the Iraqi database, which utilizes the particle swarm optimization (PSO) approach. A data set of 187 historical ground-motion recordings in Iraq's tectonic regions was used to build the explicit proposed models. The proposed PGA models relate to different seismic parameters, including the magnitude of the earthquake (M w), average shear-wave velocity (V S 30), focal depth (FD), and nearest epicenter distance (R EPi) to a seismic station. The derived PGA models are remarkably simple and straightforward and can be used reliably for pre-design purposes. The proposed PGA models (i.e., models I and II) obtained via the explicit formula produced using the PSO method are highly correlated to the actual PGA records owing to low coefficients of variation (CoV) of approximately 2.12% and 2.06%, and mean values (i.e., close to 1.0) of approximately 1.005 and 1.004. Lastly, high-frequency, low absolute relative error (ARE), which is below 5%, is recorded for the proposed models, thereby showing an acceptable error distribution. [ABSTRACT FROM AUTHOR]

The macroseismic intensity of the February 6, 2018, Mw 6.4, Hualien earthquake, which caused extensive damage around the Hualien area of eastern Taiwan is reassessed using the Environmental Seismic Intensity (ESI-07) scale. We compiled data on earthquake environmental effects (EEEs) caused by the 2018 Hualien earthquake, which includes surface ruptures, ground cracks, liquefaction, and occasional landslides, and estimated the epicentral intensity (I 0) as well as site-specific intensities. We found that the ESI-07 epicentral intensity of the Hualien quake in 2018 is IX. We note that the epicentral area of the 2018 Hualien earthquake was the mesoseismal area of the October 22, 1951, (M w 6.6) Hualien earthquake, as reported in primary contemporary sources and historical earthquake catalogs. The 1951 Hualien earthquakes also caused prominent surface ruptures, liquefaction, and ground cracks. Consequently, we reassess the macroseismic intensities of this historical seismic event and compare it to the Hualien earthquake in 2018. The comparison suggests similar epicentral intensities for the two earthquakes (IX and X ESI-07). Moreover, we conducted a systematic comparison between intensity obtained using different scales which revealed the differences of two to three degrees between the ESI-07 and traditional intensity scales. This result reconfirms the significance of documentation and recording of earthquake environmental effects to make intensity assessments for modern seismic events consistent with the historical earthquake records. Moreover, a re-evaluation of historical earthquake intensity in eastern Taiwan could be performed in order to update the seismic hazard map. Application of the ESI-07 intensity scale of recent and historical earthquakes will be helpful in post-earthquake recovery efforts for a future earthquake. The prepared ShakeMaps from the ESI-07 values suggests completely different shapes to the previously generated ShakeMaps considering the peak ground acceleration or peak ground velocity. It suggests that the ShakeMaps prepared from the earthquake environmental effects can be complemented with the instrumental based intensity map to have a better seismic hazard prediction and future land use planning for the region. [ABSTRACT FROM AUTHOR]

Earthquake Environmental Effects (EEEs) such as surface faulting, landslides, liquefaction and tsunamis are widely distributed following strong seismic events and may account for a significant part of the overall damage. Here, we investigate EEEs generated by two earthquakes with different source parameters, both occurring along the Mexican subduction zone: the Sept. 8, 2017, Mw 8.2, moderate depth, normal fault, intraslab event; and the June 23, 2020, Mw 7.0, shallow depth, thrust fault, interface event. We document the EEEs for each event, assign an intensity value using the Environmental Seismic Intensity (ESI-2007) scale, and derive the macroseismic fields. Finally, we compute the attenuation of intensity with distance and we compare it with other subduction zone earthquakes worldwide, demonstrating the repeatability of EEEs. This work represents the first application of the ESI-2007 scale to an intraslab earthquake and documents its wide applicability in different seismotectonic settings. We argue that EEEs provide useful information that should not be neglected in seismic hazard assessment procedures. [ABSTRACT FROM AUTHOR]

This work presents a macroseismic analysis of the AD 1755 Lisbon Earthquake-Tsunami event by means of the combination of intensity data derived from the EMS-98 scale and the ESI-07 scale (Environmental damage). About 600 records of secondary earthquake environmental effects (EEEs) for the whole Spain have been used to define intensities, focused on the SW portion of the Iberian Peninsula. The Spanish data have been complemented with 308 EEEs records from Portugal. The analyses indicate maximum intensities of X EMS-ESI along the Atlantic margin of the Iberian Peninsula with 76 records of Tsunami environmental effects (TEEs). An important amplification (VIII – VII) occurred all along the Guadalquivir basin and the adjacent Betic front at epicentral distances of 300–700 km. In these zones 55 records of ground effects (ground cracks, Liquefactions and slope movements) are catalogued. In the rest of the territory of the Peninsula the most widespread effects were hydrogeological changes with 505 records in Spain and 196 in Portugal (total 701 records) covering all the intensity levels. Increase of flow discharges in springs and elevation of water level in wells was the common groundwater response to seismic shacking, especially in SW Iberia. In this zone water elevation in wells was between 5 and 3 m and persistent increases of discharges long-lasting (several days to two months). Persistent discharges on springs were linked in 143 cases to important SW-NE crustal faults (e.g., Alentejo-Plasencia Fault). From the Intensity distribution the historic seismic scenarios are explored by means of the development of empirical ShakeMaps. These consider the three classical seismic sources proposed for this earthquake: Gorringe Bank (G); Marques de Pombal Fault (M) and Atlantic delamination beneath the Gulf of Cadiz (C). However, individually these seismic sources are too small and unable to generate the resulting seismic scenario depicted by the intensity map developed in this work, with onshore seismic accelerations (PGA) up to 0.82 g. These acceleration values and the great amplification experienced throughout the Guadalquivir basin (0.34–0.52 g) are only possible considering a combination of the three seismic sources (GMC Source) probably related to shallow subduction or lithospheric delamination beneath SW Iberia and the Gulf of Cadiz. This will suggest an NNE-SSW offshore rupture length of 350–360 km with an overall rupture area of c. 84,500 km2 resulting in an event magnitude 8.6 Mw calculated from empirical relationships. The results demonstrate the efficacy of these kind of approaches for better identifying and modelling seismic sources for historical events. [Display omitted] [ABSTRACT FROM AUTHOR]

To clarify the effect of various anchor cable failure modes on the dynamic responses of slopes, the FLAC3D software was redeveloped. Constitutive models of cable elements in different anchor cable failure modes were proposed and embedded into the main program of slope dynamic calculation. The axial force, acceleration, and displacement responses in different anchor cable failure modes were compared and analyzed. The effects of seismic parameters on the anchor cable failure modes were also investigated. A matching relationship between the ultimate load-bearing capacities of the anchorage, anchoring interface, and tendon was proposed. The results reveal that the seismic intensity causing anchor cable damage in anchorage failure mode (AFM) and grouting body failure mode is 0.2g–0.3 g lower than that in tendon failure mode. At the moment of failure, the stress released by the anchor cable in AFM is the highest, with the most evident instantaneous slope acceleration fluctuation. In the collaborative seismic design of the anchorage, anchoring section, and anchor tendon, the ultimate load-bearing capacities of the anchorage and anchoring interface should be increased by 1.8 times to match the tensile bearing capacity of the tendon. This study provides a reference for the seismic anchorage design of slopes and offers suggestions for selecting seismic design parameters for anchor cables. • FLAC3D software is redeveloped, and the constitutive model of the cable element is modified. • A dynamic model of the slope considering different anchor cable failure modes is established. • The influence of the failure mode of the anchor cable on the dynamic response of the slope is clarified. • The influence of seismic wave parameters on the failure mode of anchor cable is studied. • A matching relationship of the ultimate bearing capacity of anchor cables under seismic action is proposed. [ABSTRACT FROM AUTHOR]

This paper proposes a self-centering rocking steel frame with column mid-height uplift (SCRSF-CMU) that exhibits high post-yield stiffness and energy dissipation capacity. The hysteretic performance of the SCRSF-CMU was investigated through cyclic loading tests. A numerical model of the SCRSF-CMU was established and validated against experimental results. Subsequently, the seismic performance of the SCRSF-CMU was compared with that of the self-centering rocking steel frame with column base uplift (SCRSF-CBU) using nonlinear time history analysis. Finally, the seismic responses of the SCRSF-CMU and SCRSF-CBU under varying earthquake intensities were analyzed using the endurance time analysis. The results indicate that the designed SCRSF-CMU demonstrates excellent lateral force resistance, energy dissipation, and self-centering capabilities. The rocking effect and the restoring force of the post-tensioned steel strands effectively controlled the residual lateral displacement of the specimens. The multi-scale numerical model of the SCRSF-CMU accurately captured its hysteretic behavior and deformation patterns. Compared to the SCRSF-CBU, the SCRSF-CMU exhibited superior rocking deformation capacity, post-yield stiffness, and hysteretic energy dissipation. Under MCE excitation, both SCRSF-CMU and SCRSF-CBU showed uniform inter-story drift distribution with minimal residual deformation, creating a satisfactory condition for the post-earthquake repair work if necessary. The high post-yield stiffness of the SCRSF-CMU was more effective in reducing both maximum and residual displacements. Endurance time analysis revealed that SCRSF-CMU and SCRSF-CBU exhibited relatively uniform inter-story drift distribution under SLE, DBE, and MCE earthquakes. Under FE excitation, the inter-story drift ratio of both structures were nearly identical; however, under DBE and MCE excitations, the maximum roof drift ratio and inter-story drift ratio of the SCRSF-CBU were larger, indicating that the SCRSF-CBU had higher deformation demands than the SCRSF-CMU. • A self-centering rocking steel frame with column mid-height uplift (SCRSF-CMU) has been proposed, featuring high post-yield stiffness and energy dissipation capacity. • The SCRSF-CMU demonstrates excellent lateral resistance, energy dissipation, and self-centering capabilities, achieving a recovery rate of over 90 % at a 2.5 % roof drift ratio. • SCRSF-CMU demonstrates superior rocking deformation capacity, higher post-yield stiffness, and better hysteretic energy dissipation compared to SCRSF-CBU. • Under MCE excitation, SCRSF-CMU maintains uniform inter-story drift angles and minimal residual deformations, facilitating easier post-earthquake repairs. • Both SCRSF-CMU and SCRSF-CBU show uniform inter-story drift ratios, but SCRSF-CBU has higher deformation demands under DBE and MCE. [ABSTRACT FROM AUTHOR]

It is acknowledged that various sources of uncertainties play a vital role in the seismic vulnerability of slope systems, while many studies ignore these sources in seismic assessments. This is because seismic performance and fragility evaluation of large soil-structure systems is challenging and computationally intensive by conventional nonlinear dynamic analysis methods, especially when the modeling uncertainties are considered. To address this challenge, this paper proposes a new framework for addressing uncertainties in the seismic evaluation of earth slopes using the Endurance Time Analysis (ETA) method. The ETA method is a dynamic pushover procedure in which the slope is subjected to a limited number of artificial intensifying records, and seismic responses are obtained over a continuous range of seismic intensities. For the purpose of this study, probabilistic two-dimensional numerical simulations of earth slopes are created using the FLAC software by considering the soil parameters uncertainty. Latine Hypercube Sampling is employed to generate random simulations. The models are then subjected to the intensifying prefabricated excitations based on the ETA method, and the fragility curves of the slope are obtained in three damage states by considering and not considering uncertainties. The results indicate that as the endurance time, which is a kind of intensity measure, increases, the uncertainties of seismic responses also increase. This shows that the effects of uncertainties become more significant when the slope is subjected to strong ground motions. Additionally, the influence of modeling uncertainty is negligible in the slight damage state, but significant in the extensive damage state. The proposed framework provides an effective and rapid way for performing the fragility and associated risk analysis of earth slopes considering uncertainties. • An efficient framework is proposed for incorporating uncertainties in fragility and vulnerability assessment of earth slopes. • The ETA method is utilized to significantly reduce the required computer run time in nonlinear dynamic analyses. • Ignoring the variability of soil properties can lead to a significant underestimation of the failure probability outcomes. • The OVAT analysis is performed to identify the influence of random variables on annual failure probability of the slope. [ABSTRACT FROM AUTHOR]

Since the Fukushima nuclear accident, seismic design requirements have increased, necessitating a more refined evaluation of base uplift for weakly anchored nuclear island buildings. The elevated cooling water over 3000 t is a distinguishing feature of third-generation reactor buildings (RBs). To assess potential safety-adverse coupling effects, seismic wave propagation process through viscoelastic soils, discontinuous interfaces, and sloshing water was analysed. To facilitate nonlinear systematic simulation and parametric study, the traditional soil-structure interaction direct methods are improved and programmed on: thickness-independent viscous-spring elements for stable static-dynamic boundary transitions; seismic forces separated from the artificial boundary for flexible mesh planning; elevated water simulated with gravity stacking and hydrodynamic action. A nuclear island region encompassing water-cooled RBs and underlying soil cushion layer was investigated as a typical scenario to reveal rules using the proposed high-precision simulation platform. Non-negligible structural risks and correlations between multiple factors were quantitatively elucidated according to simulation findings. A time-lagged increase in the base overturning moment may occur because of water oscillations. As the water level increases to 85 %, the uplift height increases, adversely affecting the in-structure response spectra. Earthquake-induced intense uplift may lead to an increase in hydrodynamic pressure along the inner wall. The research results support the practical assessment of buildings with water cooling facilities located in soft composite sites with high seismic intensities. • Global simulation platform for seismic performance assessment of water-cooled nuclear island buildings with potential uplift. • Derivation and implementation of thickness-independent viscous-spring boundary element. • Discussion on intricate relationships between interface behaviors, water sloshing, and structural risks in severe earthquake. • Comparison of wave motions in structure-soil system considering interface continuum and uplift reveals notable discrepancies. [ABSTRACT FROM AUTHOR]

In response to the shortcomings of isolation bridge limit devices and friction dampers, a sliding friction bearing exhibiting multi-level working behavior (MSFB) is proposed. Its structure and mechanism are introduced, and a multi-condition quasi-static test is conducted using ABAQUS software. Through comparative analysis of theory and experiment, the theoretical model's accuracy and multi-level sliding friction mechanism of MSFB are verified. The mechanical parameters of MSFB are analyzed, clarifying the influence of various main mechanical parameters on the mechanical performance. The performance parameters of the MSFB are optimized based on a two-degree-of-freedom analysis model for a high-speed railway single-pier bridge equipped with MSFBs. The findings indicate that the seismic responses of MSFB is comprehensively affected by all the parameters, and the variation pattern is complex. By optimizing these performance parameters, MSFB can satisfy the multi-level performance demands of bridges subjected to varying earthquake intensities, and achieve the optimal control effect. The MSFB offers superior isolation efficiency during minor and moderate earthquakes and can substantially decrease the internal forces within the bridge substructure when utilized as a bridge isolation and limit device. During intense and infrequent earthquakes, the MSFB demonstrates remarkable displacement-limiting capacity and good self-centering and energy dissipation abilities. • A sliding friction bearing exhibiting multi-level working behavior is proposed. • The theoretical model's accuracy and multi-level sliding friction mechanism are verified. • The performance parameters are optimized for a high-speed railway bridge equipped with MSFBs. • MSFB can satisfy multi-level performance demands subjected to varying earthquake intensities. [ABSTRACT FROM AUTHOR]

This study investigated the seismic response of a long shield tunnel crossing multiple soil deposits. The P2PSand model and practical-oriented hysteretic model were used to simulate the cyclic behaviour of liquefiable sand and soft clay, respectively. A refined tunnel model was adopted to simulate the mechanical behaviour of segmental linings. Dynamic analysis was then performed to explore the seismic response of shield tunnels passing through liquefiable sand and soft clay under transverse or longitudinal asynchronous ground motions. The joint displacement and lining force were found to be prominent near the interface between the liquefiable sand and soft clay. The counterintuitive seismic deformation mechanism of tunnel structure was then clarified. Parametric studies were carried out to elucidate the tunnel deformation mechanism. The seismic responses of the tunnel structure under longitudinal ground motions were more prominent than those under transverse ground motions. The earthquake intensities, relative densities and liquefaction potentials of sand, and clay stiffness exerted major influences on the seismic response of tunnel structure, while the interface inclinations and earthquake wave velocities had a slight impact on the tunnel seismic response. [ABSTRACT FROM AUTHOR]

The reliability assessment for running safety of vehicle on slab track under temperature action and seismic excitation is challenging due to the extensive computational efforts. This study proposes an improved second-order fourth-moment (ISOFM) approach for the reliability analysis for running safety of vehicle on slab track under temperature action and seismic excitation. The dimensionless limit state function (LSF) for running safety of vehicle on slab track is formulated considering four failure modes. The proposed ISOFM approach is verified by the Monte Carlo simulation (MCS) method. The proposed ISOFM approach greatly reduces the number of computations of nonlinear LSF. The merit of the proposed ISOFM approach lies in significantly enhancing the computation efficiency and precision of reliability considering nonlinear LSF with multi-failure modes. Additionally, the influences of temperature action and seismic excitation on the reliability for running safety of vehicle on slab track are discussed. The reliability for vehicle running safety decreases more significantly with the increment in overall temperature compared to the positive temperature gradient (PTG). The reliability for running safety of vehicle on slab track decreases nonlinearly with the increase of the earthquake intensity. [ABSTRACT FROM AUTHOR]

Most seismic risk assessments primarily focus on the impact of ground acceleration on infrastructure. However, in Mexico, along with numerous countries in Latin America and beyond, a significant portion of earthquake risk stems from secondary environmental effects such as tsunamis, landslides, and liquefaction processes. These secondary effects can often prove more lethal than the earthquake shaking itself. We used the Environmental Seismic Intensity scale (ESI-07) to assess the Earthquake Environmental Effects (EEEs) of the M w 7.7 Michoacan earthquake on September 19th, 2022. This made it possible to comprehensively characterize the EEEs and their potential social consequences in the epicentral area along the Mexican subduction zone. Our study draws on data gathered from extensive field surveys, satellite imagery analysis, social media monitoring, and online resources, totalling data from over 8000 sites with EEEs. Through rigorous analysis, ESI-07 intensity values illuminate the vulnerability of coastal areas and coastal ranges to specific secondary effects triggered by large seismic events. We meticulously map the spatial distribution of these triggered EEEs, presenting A) an ESI-07 isoseismal map, and B) comparative analysis with other significant earthquakes, particularly subduction megathrust interface events. Our findings underscore the critical importance of considering environmental coseismic effects and using the ESI-07 scale in territorial planning and seismic risk preparedness. Furthermore, we highlight the unique characteristics of the Mexican Pacific coastal region and, more broadly, the distinct risks posed by coastal areas along subduction zones in terms of secondary seismic environmental hazards. This work emphasizes the urgent need to acknowledge the vulnerability of these regions to secondary effects and the imperative for resilience-building measures to safeguard human well-being and mitigate economic repercussions in the face of future seismic events. • The ESI-07 scale was applied to assess the EEEs caused by the 09/19/2022 earthquake. • We document more than 8000 EEEs resulting from the Michoacán 09/19/2022 earthquake. • Secondary seismic effects can be more dangerous and deadly than the main earthquake. • Mexican Pacific coastal is vulnerable to EEEs specially landslides, liquefaction. • EEE intensity and spatial distribution are presented by the ESI-07 isoseismal map. [ABSTRACT FROM AUTHOR]

• A new data-driven model (SeismNet) for simultaneous prediction of magnitude and instrumental intensity in the north–south seismic belt of China is proposed. • SeismNet fulfills the requirement of rapid and accurate prediction of magnitude and instrumental intensity in earthquake early warning. • The performance of SeismNet is better than that of the baseline model and allows for more desirable threshold alarms. • SeismNet consistently predicts better than the traditional method Pd and single-task model with the increase of input data. The seismic activity in the north–south seismic belt of China is among the highest in the world. Predicting instrumental intensity and magnitude after an earthquake mitigates regional seismic disasters. The standard workflow for prediction involves building empirical formulas using characteristic parameters of the initial arrival seismic wave, but this method has limitations in accuracy. Recent data-driven models have shown promise in predicting instrument intensity and magnitude. Still, this is currently done mainly on a single-task basis and does not consider whether a multi-task model can utilize complementary information from different tasks to improve overall performance. This study proposes a data-driven multi-task model called SeismNet, which can simultaneously predict instrument intensity and magnitude. We tested the effectiveness of SeismNet using ground motion records of the north–south seismic belt of China. The model can predict instrument intensity and magnitude more rapidly and accurately than the baseline and single-task models, with increasing accuracy as the input seismic wave duration increases. We also tested the method on three destructive earthquake events (Ms > 6.5) that occurred in China and found that at 3 s after the P-wave arrival, the prediction is almost consistent with the observation. Overall, this study offers a new method for improving earthquake prediction accuracy in the North-South seismic belt of China. [ABSTRACT FROM AUTHOR]

A key component of any probabilistic seismic hazard analysis (PSHA) is the capability of predicting ground motion intensities for future earthquakes with different characteristics and occurrence frequencies. Ground motion models (GMMs) have been the preferred tools to predict, in a probabilistic manner, the size of the ground motion as a function of the earthquake's rupture parameters (i.e., location, depth, orientation of the rupture plane, rupture area, and rupture shape, among others). For this purpose, two different approaches have been used in PSHA practice. The first one, widely used and with hundreds of available models, are semi-empirical derivations of GMMs for response spectral values. The second one, which is less used in professional practice, requires the development of the predicting model for the Fourier amplitude spectrum (FAS) and the duration of the strong motion, to convert them into response spectral values through random vibration theory (RVT). The second approach, although computationally complex, should be preferred when site-effects are considered in the PSHA since these can be incorporated in a more efficient and theoretically correct way. Also, this second approach allows estimating hazard levels for different damping ratios and other hazard intensity measures such as peak ground velocity (PGV) and peak ground displacement (PGD) straightforward. This paper shows the methodology and results of a PSHA for Mexico City, a place with well-known existence and relevance of site-effects, carried out exclusively using Fourier-based GMMs, developed to be representative for the different types of earthquakes that contribute to earthquake hazard in the city (i.e., interface, intraslab, and crustal). The strategy to estimate ground motions in Mexico City consists in obtaining FAS-based ground motion models for a reference firm ground station and multiplying the computed FAS by an empirical transfer function that describes the frequency-dependent amplification factors between the reference station and the soft site of interest. • A PSHA was carried out for Mexico City using Fourier-based ground motion models. • Site-effects in PSHA are more transparent when using Fourier Amplitude Spectra GMMs. • The results of this PSHA are used today to obtain the design spectra in Mexico City. • Fourier-based GMMs allow estimating any damping values and intensity measures. [ABSTRACT FROM AUTHOR]

This study proposes a method for predicting the seismic response of structures using seismic information and structural properties. In the proposed method, the relationship between seismic and structural characteristics and seismic responses was investigated using a convolutional neural network (CNN) to predict the seismic response. Spectral acceleration (Sa) calculated from the seismic wave was selected as seismic information used in CNN-based seismic response prediction techniques. The study introduced seismic information and structural properties, which correspond to the parameters to express the structure's unique characteristics or nonlinear hysteretic behaviors that determine the response characteristics of the structure subjected to seismic waves. Meanwhile, Sa and structural properties were utilized to constitute the input map of CNN and predict the maximum inter-story drift ratio that corresponds to the output of CNN. As data corresponding to the period range of interest rather than a scalar value for a specific period, Sa is rearranged in matrix form to constitute the input map of CNN. Structural properties are also placed in the input map of CNN as scalar values are converted into conditional vectors. To confirm the validity of the proposed method, multiple CNN-based models with changes in the information of the input map are presented, and their prediction performances are compared. Furthermore, CNN-based models that additionally consider seismic intensity measures are presented, and their influences on seismic response prediction performance are analyzed. In addition, a vast number of linear and nonlinear structures were generated, and seismic responses extracted via seismic analysis of multiple earthquakes were used to create datasets for training the presented models. The prediction performance of the presented models trained using the datasets was compared. The validity of the simultaneous use of structural properties with Sa, the introduction of conditional vectors, the additional use of seismic intensity measures, and their contributions to improving prediction performance were also examined. • A CNN-based seismic response prediction method is presented. • Seismic and structural properties are considered in the method. • A conditional vector form for structural properties is proposed and used in the input of the CNN. • Spectral accelerations of ground motions are employed as seismic properties into the CNN. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic response of a model pile-soil-bridge system subjected to seismic loading using a finite element model (FEM) developed in OpenSees. The numerical model is validated against shake table test data from a companion experimental study, which tested a piles-bridge model fabricated from organic glass. The bridge model comprised four piers, each supported by two-by-two pile groups, with edge piers featuring 60 × 60 mm rubber pads between the pier and deck. Two earthquake ground motions, El Centro and Tianjin, were applied at three intensity levels. The calculated and measured responses show good agreement. The validated FEM reveals that the El Centro earthquake typically induces higher acceleration and moment responses in structural elements compared to the Tianjin earthquake, while the Tianjin earthquake results in greater displacement responses. These findings highlight the impact of earthquake wave characteristics, such as predominant period, on the bridge system's response. Furthermore, the bending moments at the pier top for edge piers remain relatively consistent across different earthquake motions and intensity levels, indicating the role of rubber pads in mitigating seismic forces in the piers. • Finite element analyses of Pile-soil-model bridge seismic tests are conducted. • FE models are validated with shake table test data. • Seismic response of pile-soil-bridge elements are elaborated revealing effects of earthquake characteristics. • Kinematic and inertial soil-structure interaction effects are evaluated. [ABSTRACT FROM AUTHOR]

Multi-stage anchoring lattice beam is widely used to support high slope in high earthquake intensity area, while the seismic behavior and interaction are not very clear. The previous studies mainly focused on a single-stage slope, while the analysis of multi-stage effect on the seismic response of anchoring lattice beam is lacking. Subsequently, a shaking table experiment was carried out to investigate the dynamic characteristics and seismic responses of a three-stage slope supported by an anchoring lattice beam. The displacement mode and the residual displacement are observed by Digital Image Correlation (DIC) technology. Kobe and Landers ground motions were input in shaking table test with an increasing order of shaking intensity. The original Kobe motion was applied at the last sequence to investigate the effect of frequency characteristic of ground motion. The results show that the acceleration response increases nonlinearly along the height of three-stage slope, and a reduction of acceleration response is observed at platform. The energy within a frequency band close to natural frequency of three-stage slope is especially amplified. The anchor takes more responsibility to resist the seismic loading, and decreases the earth pressure behind lattice beam. By setting multiple stages, the acceleration amplification and seismic earth pressure are reduced effectively. The intensity and the frequency characteristic of seismic motion affect the axial strain of anchor. The potential local failure and the frequency characteristic of seismic motion are suggested to be considered in seismic design. • The dynamic characteristic and response of a three-stage anchoring lattice beam were studied by shaking table test. • The modal parameter, horizontal and vertical acceleration, displacement, axial anchor strain and earth pressure were studied. • The effect of seismic ground motion and multi-stage effect on seismic response are analyzed. [ABSTRACT FROM AUTHOR]

Seismic fragility of substation equipment is vital in risk analyses, as well as post-earthquake prediction of failure probabilities of multiple equipment for deciding the inspection order. However, the existing fragility curves of equipment are commonly generated without adequately considering intensity measures (IMs) of ground motions. During the post-earthquake use, they are deemed applicable to any earthquake occurring in the region, which is insufficiently precise. Thus, this paper employs a new method to derive more refined fragility curves for substation equipment based on ground motion classifications. It uses principal component analysis to convert IMs into a small number of principal components (PCs). Taking the PCs as indices, the selected ground motions are clearly categorized into distinct classes using the K-means clustering algorithm. Then, a simulation model of equipment is developed and the time-history dynamic analyses are performed to calculate seismic responses under different classes of ground motions. Finally, the refined fragility curves are derived via multiple stripe analysis for each ground motion class. A 500 kV power transformer is used as a case to implement the method. The results show that a small number of PCs can effectively reflect the multiple ground motion characteristics. Different ground motion classes have distinct distributions of IMs and PCs. There are notable discrepancies in the fragility curves of the power transformer when subjected to different ground motion classes. The significant disparities between the refined and original unclassified fragility curves highlight the importance of considering ground motion classifications. • Clustering of ground motions was introduced into seismic fragility analysis of substation equipment. • Principal components analysis on seismic intensity measures was performed. • Principal components were proposed as indices for ground motion classification. • A batch of ground motions was clustered as six classes with distinct characteristics. • Refined seismic fragility curves of a 500 kV power transformer were obtained and compared. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (OWTs) are gaining prominence worldwide, and the hybrid pile-bucket foundation, which combines a monopole and a bucket, has emerged as a noteworthy development. In this study, a 3-D numerical model for the 5-MW OWT was constructed utilizing the OpenSees platform. The dynamic characteristics of the sand was modeled with the PDMY02 constitutive model and the soil was discretized using brick u-p elements. To investigate the dynamic behavior of the OWT in an actual marine environment, the coupled model was subjected to dynamic loadings, encompassing waves, wind, and earthquake. Two seismic motions with different frequency components were considered, respectively. The study focused on exploring the impacts of key influencing factors on the OWT rotation, tower-top acceleration development and spatiotemporal distribution of excess pore water pressure ratio (EPWPR). These factors include dynamic load combinations, earthquake intensity, soil relative density, wind speed, angle between load directions, and pile length. It is revealed that the inclination angle of offshore wind turbines (OWTs) may exceed the allowable threshold under specific conditions of load combinations, seismic motion inputs, and seabed conditions. Thus, it is suggested to appropriately consider the effects of wind and wave actions in the seismic analysis of OWTS. • A 3-D numerical model of 5 MW OWT with hybrid pile-bucket foundation was developed. • Two seismic motion inputs with different frequency components were considered. • The wind and wave loads were generated and imposed at different parts of OWT. • Soil liquefaction, acceleration and rotation angle tower were illustrated. • Load combination, earthquake intensity, soil relative density, wind speed, loading angle and pile length were considered. [ABSTRACT FROM AUTHOR]

Many grain silos in earthquake intensity areas are at significant risk of post-seismic damage, which compromise their functionality and pose an enormous challenge to post-disaster rescue and social stability. However, the current specifications based on fixed-base foundations are not fit for the seismic design of silos in soft soil areas. Therefore, it is of great practical significance to study the seismic disaster prevention of siloes considering soil-structure interaction (SSI) for food security and post-disaster supply. In this research, a column-bearing silo in a soft soil area is taken as the research object. The relative displacement response, elastic-plastic development and storage lateral pressure of the structure under different ground motions are studied in detail when the state of filling storage material is empty, half-filled and fully filled. Compared with the fixed-base model, the mechanism of the ground motion response and the influence of the SSI effects on the dynamic characteristics of the column-bearing silo structure under different storage conditions are revealed. In addition, structural vulnerability analysis is carried out with the incremental dynamic analysis (IDA) method. Finally, the structural damage probability with and without SSI effects under different storage conditions is further discussed. The results demonstrate that the SSI effects have a certain damping effect on the column-bearing silo. The amount of storage material changes the failure probability of the structure. Moreover, full-silo is the most dangerous condition, indicating that the filling state of storage material affects the stiffness degradation. This study provides theoretical insight to the influence of the SSI effect on the seismic resilience of structures. • The influence of SSI on the structural dynamic characteristics and the material lateral pressure are investigated. • The elastic-plastic development coefficient of displacement is proposed to evaluate the safety of the structure. • The vulnerability assessment of the silo with or without SSI effects under different storage conditions is discussed. • The influence of storage material on the failure probability of the structure is evaluated. [ABSTRACT FROM AUTHOR]

Transformers and their bushings are critical equipment pieces in power substations, which are often exposed to significantly high seismic risk. To enhance the seismic performance of the transformer-bushing system, isolation through double friction pendulum (DFP) bearings has been considered. However, the selection of appropriate isolation parameters lacks theoretical guidance and efficient analysis methods. A theoretical model for the transformer-bushing system isolated with DFP bearings has been proposed. Based on this model, isolation parameters that ensure acceptable displacement response while achieving optimal acceleration isolation efficiency can be determined. Taking a high-voltage transformer isolated by DFP bearings as an example, a set of isolation parameters is optimized and used to design a shaking table test. The results demonstrate that the proposed model exhibits reliable calculation accuracy for the seismic response of the transformer-bushing system, regardless of whether it is isolated or not, within the range of peak ground acceleration(PGA) of 0.1–0.6 g. Moreover, at 0.4 g, the experimental results indicate that the isolation efficiency remains consistent with the parameter optimization, approaching 50 %. This research contributes to the understanding of seismic resistance and isolation strategies for transformer-bushing systems, providing valuable insights for the selection and optimization of isolation parameters in practice. • A novel theoretical model for transformers with double friction pendulum bearings. • A guide to optimize isolation parameters of double friction pendulum bearings. • Achieving an isolation efficiency of 50 % at high seismic intensity (>0.4 g). • Model effectiveness and isolation efficiency validated by shaking table test. [ABSTRACT FROM AUTHOR]

• The seismic hazard model of the optimized macroseismic intensity standard is improved. • The fragility prediction model of regional buildings considering optimized intensity measures is innovatively proposed. • An optimized Gaussian distribution model is proposed. Macroseismic intensity measures are fundamental quantitative indicators for evaluating the vulnerability and resilience of regional building clusters. The vulnerability model of building portfolios established can provide a noteworthy reference for the development of large-scale regional earthquake risk distributions. However, there are differences in the quantitative scales of the macroseismic intensity standards used in multiple regions. The positive effects of instrument intensity and probabilistic seismic hazard theory on the vulnerability assessment of regional buildings are rarely considered, resulting in significant differences in their assessment results. This paper comprehensively considers the impact of instrument intensity and seismic hazard models on traditional macroseismic intensity. An updated macroseismic intensity measure (UCMS-20) is proposed for evaluating regional buildings, which is combined with the latest version of China's seismic intensity standards. The actual seismic damage sample dataset (31,649 buildings) of four types of building clusters in three typical earthquakes in China (Wenchuan 2008, Yushu 2010, and Jiuzhaigou 2017) has been expanded and updated. Using the UCMS-20, the European Macroseismic Scale (EMS-98), the Modified Mercalli intensity (MMI), and the Medvedev, Sponheuer, and Karnik Scale (MSK-64), vulnerability assessments are conducted on the extended empirical structural seismic damage dataset, and an empirical disaster matrix model considering updating damage states is established. A nonlinear vulnerability prediction model considering updated macrointensity measures is proposed, and the optimized model is validated and compared against the developed multiscale empirical structure dataset. The multiscale vulnerability index calculation model is improved, and novel optimization curves, point clouds, and matrix probability risk models are established, considering the expansion of empirical structural vulnerability databases. [ABSTRACT FROM AUTHOR]

• Novel anisotropy tomography of upper mantle beneath central Mediterranean. • Seismic tomography from splitting intensity inversion. • 3D changes in direction and intensity of seismic anisotropy down to 300 km depth. • Fine details of slab geometries and mantle flow patterns are recognized. The region between central Europe and the centre of the Mediterranean is characterised by complex tectonics and kinematics. Here, the interaction between thickened crust, subducting lithosphere and surrounding asthenosphere produces strong and pervasive anisotropy in the upper mantle. Shear wave splitting measurements, the most adopted method to image seismic anisotropy so far, when interpreted in a ray-based framework result in little or no depth resolution, hampering a correct image of the anisotropy distribution with depth. In this study, we aim to better constrain the depth-dependent seismic anisotropy beneath Italy and surrounding regions, by isolating for the first time the source region of anisotropy at different depths. To do that, we perform an anisotropy tomography, adopting the splitting intensity inversion method. It is entirely based on the finite-frequency effect in the splitting of SKS waves. We first computed the splitting intensity using SKS waves recorded at all available permanent and temporary stations over the region, obtaining a huge dataset of measurements used as an input for the tomographic inversion. The large-scale 3D model of seismic anisotropy obtained with the inversion shows a clear change of anisotropy properties in terms of fast polarisation direction and intensity for different depths, thus improving the characterization of the main sources of anisotropy in the mantle as a function of depth. Shallower layers (70–100 km depth) are characterised by a complex and variable oriented pattern of anisotropy fast direction and intensity, which becomes progressively more organised with depth (100–300 km). This pattern suggests a strong control exerted by the geometry and motion of the different slab segments and the large-scale asthenospheric flow generated by subduction and roll-back processes. The strength of anisotropy increases with depth, with high values affecting the bulge of the Alps and Apennines chains and the southern Tyrrhenian subduction system. On the contrary, weaker anisotropy characterises the transition zone from the Apennines to Alpine domains beneath the Po plain, and both the Adriatic and European domains. [ABSTRACT FROM AUTHOR]

The research aims to improve seismic ductility design by introducing self-centering tension-only braces (SC-TOBs) as a replacement for traditional components prone to elastoplastic damage. These innovative braces are engineered to withstand tension without undergoing compression buckling, thereby enhancing energy dissipation, and minimizing residual deformation post-earthquake. To validate this concept experimentally, a three-story common steel frame (CF) structure was modified to incorporate SC-TOBs, creating self-centering brace-frame (SCF) structures. Two variations of the SCF structures were tested: SCF-A, with prestressed SC-TOBs, and SCF-B, with unprestressed SC-TOBs. Shaking table tests were conducted on these models under three seismic intensity levels: frequently occurring earthquake (FOE), moderately occurring earthquake (MOE), and rarely occurring earthquake (ROE). The results indicated that the SCF-A structure exhibited almost no cumulative residual deformation, whereas SCF-B showed a significant reduction in deformation compared to the CF structure. The prestressed SCF-A demonstrated smaller displacement responses than both CF and SCF-B structures. Additionally, peak base moments in SCF-A and SCF-B structures were reduced by 32.5 % and 45.6 %, respectively, compared to the CF structure. Under ROE seismic intensity, the SCF structures achieved a maximum floor acceleration amplification ratio of approximately 0.71, significantly better than the CF structure. These findings suggest that SC-TOBs, with their distinctive deformation mode and elastoplastic stiffness, are a viable solution for enhancing the seismic resilience of frame structures. By carefully designing the hysteresis behavior of SC-TOBs, the study demonstrates the potential to effectively control structural responses during seismic events, thereby offering a promising approach to improving earthquake resilience in building design. • A new self-centering tension-only braces (SC-TOBs) for enhanced seismic resilience is proposed. • Shaking table tests showed that the self-centering brace-frame (SCF) structures exhibited reduced residual deformation. • Prestressed SC-TOBs demonstrated superior seismic performance, showcasing potential for safer seismic-resistant buildings. [ABSTRACT FROM AUTHOR]

This paper explores the seismic fragility assessment of historical masonry buildings in the context of performance-based earthquake engineering, using multiple-record incremental dynamic analyses (MR-IDA). The methodology is applied to two case studies, the first being a stiff monumental structure, and the second a tall and slender masonry building. Both case studies are modelled in the OpenSees software using three-dimensional macroelements that account for the in-plane (IP) and out-of-plane (OOP) response of masonry walls. Simultaneously, the numerical models account for the influence of non-linear connections in floor-to-wall interfaces and wall-to-wall interlocking. The record-to-record variability induced by the random nature of the ground motion is addressed through earthquake selection consistent with the variability of European hazard. Ground motion records are normalised at a uniform level of seismic intensity to be sequentially increased for the computation of IDA curves. Once IDA curves and fragility functions are derived, the failure results are thoroughly discussed. The fragility functions accounting for the uncertainties arising from the record-to-record variability are contrasted against the results of the seismic assessments affected by multiple sources of uncertainty in material and modelling parameters from a previous study. Finally, the fragility curves derived from the methodology presented herein are directly compared with fragility functions from probabilistic seismic demand analysis (PSDA). Overall, IDA-based fragility functions are found to provide more conservative predictions than the ones obtained from the cloud-based approach using unscaled records. • Multiple-record incremental dynamic analyses (MR-IDA) for performance-based assessment of historical masonry buildings. • Case studies representative of actual buildings, considering in-plane (IP) and out-of-plane (OOP) effects. • Non-linear time history analyses using FE macro-modelling and innovative constitutive laws for non-linear connections. • Derivation of analytical fragility functions accounting for the uncertainty stemming from the record-to-record variability. • Analysis of the effect of material and modelling uncertainties vs. record-to-record variability. [ABSTRACT FROM AUTHOR]

This study investigated the seismic performance of 6-, 9-, and 12-story concentrically braced steel frames utilizing shape memory alloy slip friction dampers (SMASFDFs). For comparison purposes, identical frames equipped with self-centering braces (SCBFs) and buckling-restrained braces (BRBFs) were also designed and analyzed. The seismic performance of considered frames was evaluated through nonlinear static and nonlinear time history analysis (NLTHA) under three seismic hazard levels, i.e., frequently occurred earthquakes (FOE), design basis earthquakes (DBE), and maximum considered earthquakes (MCE). Incremental dynamic analysis (IDA) was conducted to examine the seismic responses, including peak interstory drift ratios (PID), peak floor accelerations (PFA), and residual interstory drift ratios (RID), of the designed frames under varying levels of seismic intensity. Fragility curves considering single and multiple seismic responses were obtained based on the IDA results. The results show that the SMASFDFs have comparable deformation control capacity as the BRBFs while exhibiting zero RID and more uniform deformation distribution over the building height. Moreover, in most circumstances, the joint failure probability is lowest for the SMASFDFs when considering multiple seismic responses. From a seismic design perspective, current results suggest that the SMASFDFs can be designed with the same strength reduction factor (R) if the PID is especially concerned. • The SMASFD has comparable deformation control capacity as the BRBF. • The SMASFDF exhibiting zero residual deformation and more uniformly distributed deformation over the building height • The joint failure probability is lowest for the SMASFD compared with SCBF and BRBF. • The SMASFD can be designed with the same R value as the BRBF. [ABSTRACT FROM AUTHOR]

The primary motivation of this investigation is to develop the compound ground motion intensity measure (IM) for the seismic performance assessment of aqueduct structures. To achieve this goal, taking the typical aqueduct structure in Southwestern China as a case study, a three-dimensional finite element model of aqueduct-water-foundation fully coupling system is established. Moreover, for the seismic hazard, a total of 300 as-recorded ground motions based on the design response spectrum are selected from PEER-NGA strong ground motion database, including near-field non-pulse (NFNP), near-field pulse-type (NFP) and far-field (FF). Then, the nonlinear correlation between single IM s is considered by Copula function, the compound IM is proposed that can comprehensively characterize the seismic performance of the aqueduct structure. Based on evaluation criteria, the applicability of the proposed compound IM is compared and verified. Finally, the conditional probability function and the unconditional probabilistic seismic risk analysis is employed to evaluate the seismic performance of aqueduct structures. It can be concluded that the compound IM considers the acceleration, velocity and displacement factors, which improves the correlation, efficiency and proficiency of probabilistic seismic demand analysis. Furthermore, the compound IM can help to improve the accuracy of the structural seismic performance assessment and reduce the uncertainty of structural response estimation. In summary, the findings of this study highlight the significance of proposing the compound IM and developing fragility curves when evaluating the seismic performance of aqueduct structures. • The advanced compound ground motion intensity measure for the aqueduct are developed. • The applicability of the proposed compound ground motion intensity measure is verified. • Framework for seismic performance assessment of the aqueduct is proposed. • The fragility curves generated by the single and compound intensity measure are compared. [ABSTRACT FROM AUTHOR]

Railway transportation is an important channel for emergency rescue and disaster relief. Traditionally, the method of evaluating the damage degree of bridges under different seismic intensities from the perspective of structural damage cannot be directly used to judge the traffic capacity of trains on bridges after earthquakes. It is impossible to guarantee the running safety and affect the transportation of materials after the earthquake. Because the damage state of track structure directly affects the running safety of trains, this study combines the relationship between the damage of track structure and the deformation of bridge structure after earthquake, and puts forward the transverse relative displacement of girder end (TRDGE) as the damage index of train running function of railway bridge after earthquake. Then, the OpenSees-TRBF (Train-Railway-Bridge-Foundation Coupled System Dynamic Analysis Platform) co-simulation method is used to carry out the train-track-bridge coupling dynamic calculation under different seismic damage states, and the running safety analysis database under different TRDGEs is established. Then, the Particle Swarm Optimization (PSO) algorithm is used to classify the bridge damage index of traffic capacity through different target safety speeds. Based on the probabilistic seismic demand model, the exceedance probability curve of traffic capacity damage under different seismic intensities is established. Finally, based on the curve, the running safety risk domain of trains on the bridge under different seismic intensities is obtained with a confidence level of 95 %. This study proposes a post-earthquake damage assessment method for railway bridges based on the assurance of running safety probabilities, evaluating the damage degree of the bridge with the residual traffic capacity of the bridge after the earthquake. This study can be applied to assess earthquake damage on existing railway bridges and provide references for the safe speed of trains on the bridge after an earthquake. • A seismic damage assessment method for bridge based on running safety is proposed. • The seismic damage probability curve of bridge based on running safety is established. • The post-earthquake vehicle speed threshold is established. [ABSTRACT FROM AUTHOR]

• GPDEM is used to perform the probability and reliability analysis of the rock slope. • The parameters spatial variability and seismic sequences randomness are considered. • Slip displacement is adopted to assess the dynamic reliability of the rock slope. • The seismic fragility analysis of the rock slope is conducted. A new and efficient framework for analyzing the stochastic dynamic response and reliability of the rock slope was constructed based on the generalized probability density evolution method (GPDEM). The left bank slope of Jinping dam was taken as an illustrative example and the effects of mainshock-aftershock sequence randomness, spatial variability of geotechnical materials and coupled uncertainties on the slope dynamic response and reliability were compared and analyzed for the first time. Firstly, a series of mainshock-aftershock sequences and parameter random fields were generated as stochastic factors inputs. Then, the effectiveness of GPDEM was validated by comparing with Monte Carlo Simulation (MCS). The Newmark slip displacement method was combined with GPDEM to analyze the slope dynamic response and reliability subjected to single and coupled uncertainties from a probabilistic viewpoint. Finally, the fragility curves of three risk levels were established based on the reliabilities with different seismic intensities. The result suggests that parameter spatial variability affects the dynamic response and reliability of the slope to some extent, but this effect will be overshadowed by the uncertainty of mainshock-aftershock sequences when it is considered simultaneously. Besides, aftershocks will cause the decrease of slope reliability and the impact of aftershock cannot be overlooked. [ABSTRACT FROM AUTHOR]

Considering the uncertainties associated with earthquake, seismic response of structures, damage caused by the response and the repair costs, determining Earthquake Insurance Premium (EIP) is a challenging task that requires a framework for modeling all inherent risks. Most of the models proposed for EIP determination have two basic components. The first component indicates the probability of seismic hazard (generally obtained from the probabilistic seismic hazard analysis), and the second component indicates the probability of occurrence of a given damage to the structure with respect to different seismic hazard levels (generally obtained from the fragility curves). These two components are interconnected through an intermediate parameter, known as the Intensity Measure (IM), which is of great importance in calculations and has hardly been considered so far. In this study, the dependency of EIP on the IM used in the probabilistic seismic hazard analysis and the fragility curves is analyzed. To this end, the EIP was determined for five types of buildings at low, medium and high seismic hazard levels using two IMs (peak ground acceleration and first mode spectral acceleration). The results of this study warn that the EIP can be highly dependent on the IM, so that for all studied structures, the EIP determined based on peak ground acceleration at a high seismic hazard level is nearly three times as many as the one determined by the first mode spectral acceleration. A significant finding is that when the first mode spectral acceleration is used as the IM, the ratio of EIP at different seismic hazard levels closely matches the ratio of IM at the same levels. This result can be valuable in developing insurance codes and regulations. However, this is not the case for the currently used IM, i.e., peak ground acceleration. [ABSTRACT FROM AUTHOR]

The Shore Temple in Mahabalipuram (Tamil Nadu, Southern India) exists since the late 7th century. Historical sources suggest that it was built on an island in honour of the gods Vishnu and Shiva. A former bridge over the canal, which separated the island from the mainland, and a seawall, which protected the shore from the waves are dysfunctional now, as they are located too high above the present day sea level. A holy well, part of the temple complex, reaches down to the modern freshwater lens. We suggest that about 1 m uplift occurred after the construction of the temple, the canal and the seawall, but before the construction of the well. This event during the reign of King Rajasimhan in the early 8th century most likely was caused by an earthquake of magnitude M > 6.5 that led to the uplift of the island. There are thick walls of a ruined masonry building in the former, sand-filled canal, tilted in various directions. These are evidence for liquefaction of subsoil, caused by a second earthquake of intensity IX-X. The east coast of India has remained prone to destructive earthquakes: archaeoseismology proves to be useful tool which can help to identify these areas. [ABSTRACT FROM AUTHOR]

The sliding of girder or bearing of the unbonded laminated rubber bearing (ULRB) supported highway bridge can protect its substructure from earthquake-induced damage but could cause a considerable girder displacement even unseating. This study develops a two-defense-line restraining system, consisting of a transverse steel damper (TSD) and sliding-shear-failure-dominated shear key, to reduce the girder's peak displacement and unseating risk. A practical trilinear mechanical model is proposed to describe the force-displacement behavior of the shear key and validated by comparing it with a series of test data available in the literature. Furthermore, a systematic and user-friendly seismic design optimization methodology for the ULRB-supported bridge with the two-defense-line restraining system is proposed in this study, considering different intensity levels of ground motions, especially for a maximum credible earthquake with a return period of 10000 years. The performance requirements for the ULRB-supported bridge equipped with the two-defense-line restraining system associated with different ground motion intensity levels are specified. After that, a response surface method (RSM) combined with the weighted sum method (WSM) is proposed in this study to optimize the mechanical parameters of the two-defense-line restraining system, realizing an optimal performance of different structural components and balancing the displacement demand of the girder and the force demand of substructure. Finally, this seismic design optimization methodology is implemented through a case study and proved to be feasible. • A two-defense-line restraining system is proposed for unbonded laminated rubber bearing (ULRB) supported highway bridges. • A newly trilinear mechanical model is proposed for a sliding-shear-failure-dominated RC shear key. • A response surface method combined with a weighted sum method is proposed to optimize the restraining system. • Performance-based design is achieved for ULRB-supported bridges with the restraining system considering the maximum credible earthquake. [ABSTRACT FROM AUTHOR]

Unreinforced masonry structures are vulnerable to seismic actions and frequently exhibit partial or global out-of-plane wall collapse when subjected to large intensity earthquake shaking. The installation of timber strong-backs connected to the masonry surface with mechanical fasteners is a reversible and effective strengthening solution that considerably improves the out-of-plane response of masonry walls. An analytical formulation is presented that enables the out-of-plane behaviour of unreinforced masonry walls seismically retrofitted with timber strong-backs to be described, with limit analysis theorems being utilised to establish the lateral capacity curve and the demands on the masonry wall, on the timber strong-backs, and on the fastener components of the retrofitted walls, thereby enabling the design of retrofit interventions. These analytical predictions were validated using experimentally derived data from five full-scale masonry wall tests and were also compared with simulations obtained from a numerical model developed using the software SAP2000 and adopting a simplified micro-modelling approach. Analytically derived load actions were consistent with experimental values (errors < 5 %) and were compatible with the numerical deformation results (errors < 10 %). The expected performance of various retrofitted wall configurations is then reported as support for general considerations regarding the retrofit solution. • A new method for predicting the OOP behaviour of URM walls strengthened timber strong-backs is proposed. • The design method is validated on FE simulations and experimental testing. • The analytical approach allows the optimization of the timber retrofit. • The calculations predict the response of the tested retrofitted walls adequately. [ABSTRACT FROM AUTHOR]

Numerous reinforced concrete (RC) structures are exposed to aggressive environments, such as chloride, mainshock and aftershock. These environmental and extreme loads have the potential to increase the seismic risks during structure's service life. This study introduces a practical probabilistic methodology to estimate the seismic risk of corroded RC frame subjected to mainshock-aftershock sequences. In this methodology, a time-variant modeling strategy is used to simulate the geometrical and mechanical properties of structural degraded materials. The Bayesian updating theorem is employed to calibrate the demand models, which are then used to estimate the fragilities and confidence intervals considering the model uncertainties. A Copula-based approach is conducted to generate joint probability of mainshock and aftershock intensities and the seismic hazard of the mainshock-aftershock scenario. Finally, the seismic risk and associated confidence intervals are estimated by integrating over all mainshock and aftershock intensities levels. A typical corroded RC frame structure is used to illustrate the proposed methodology. The results show that the contribution of corrosion and aftershock would lead a 10 times higher seismic risks compared to scenarios considering only mainshock damage. It is necessary to account for the influence of both corrosion and aftershock in seismic design. [ABSTRACT FROM AUTHOR]

• We obtain high-resolution Poisson's ratio and crustal thickness of the central-southern segment of the TanLu Fault Zone (TLFZ). • Areas of high Poisson's ratio and uplifted Moho are accompanied by frequent occurrence of earthquakes. • High Poisson's ratio anomaly may indicate mafic rocks that intrude into the lower crust, which acts stress concentrators and leads to large intracontinental earthquakes. • The seismotectonic segmentation along the central-southern segment of the TLFZ is influenced by varying degrees of magmatic underplating. Intracontinental earthquakes usually cause severe casualties and property damage, yet their mechanism is still unclear. The TanLu Fault Zone (TLFZ) has been a typical large intracontinental strike-slip fault in eastern China since the Quaternary, which has hosted many large earthquakes (M ≥ 6). Generation of large earthquakes is generally closely related to the heterogeneities on and adjacent to the fault plane, which may result from different composition and inclusions of fluids. In this study, we use the receiver function method to obtain detailed distributions of Poisson's ratio and crustal thickness in the central-southern segment of the TLFZ, where the M 8.5 TanCheng earthquake occurred in 1668. We found that the distribution of earthquakes is strongly correlated with the crustal structures, both of which exhibit clear segmentation. The strongly damaged zone (with earthquake intensity ≥ 10) of the 1668 TanCheng earthquake and present small-to-moderate earthquakes are generally located above a segment that has shallower Moho and particularly higher Poisson's ratio. We propose that the high Poisson's ratio may be caused by intrusive mafic rocks in the ductile lower crust, which plays a role as local stress concentrators and subsequently leads to large intracontinental earthquakes. [ABSTRACT FROM AUTHOR]

Structural systems in seismic-prone regions can experience sudden deterioration caused by earthquake-induced ground-motion sequences. In addition, given the prevailing environmental conditions at their site, these systems may undergo gradual deterioration resulting from environment-induced mechanisms. The combined impacts of such phenomena can result in significant structural/non-structural damage, leading to exacerbated consequences (e.g., repair costs, downtime, and casualties) during the systems' service life compared to the consequences due to each phenomenon in isolation. Yet, such a multi-hazard threat is commonly overlooked. This paper proposes an end-to-end computational framework for simulation-based consequence analysis of deteriorating structural systems subjected to earthquake-induced ground-motion sequences and chloride-induced corrosion deterioration. State-dependent (and time-dependent) fragility and vulnerability relationships are derived as part of the proposed workflow. To this end, a multivariate probabilistic seismic demand model and a collapse generalised logistic model are developed, linking the dissipated hysteretic energy in the ground-motion sequence, the maximum inter-storey drift induced by the first ground motion, the intensity measure of the second ground motion, and the corrosion deterioration level. The time-varying corrosion rate is described through a hurdle model, employing an appropriate (continuous) chloride-penetration model. Vulnerability relationships are derived by combining the developed fragility relationships and suitable building-level consequence models. Finally, the (expected) life-cycle consequences are estimated by subjecting the system to stochastic event sets, encompassing ground-motion sequences. The proposed framework is demonstrated through a case-study reinforced concrete building. Considering the interaction between seismic sequences and corrosion effects, the expected life-cycle consequences in terms of economic loss ratio are 125 % higher than those without considering any hazard interaction. These consequences are mainly dominated by the effects of the ground-motion sequences rather than those associated with corrosion deterioration. • Formulation of a hurdle model for characterising the time-varying corrosion rate on the analysed geographical location. • Development of a vector-valued probabilistic seismic demand model for characterising the structural response. • Development of a vector-valued collapse generalised logistic model for characterising the structural collapse. • Derivation of time- and state-dependent fragility/vulnerability relationships including sudden and gradual deterioration. • Implementation of a simulation-based consequence analysis leveraging Halton sequences to design life-cycle scenarios. [ABSTRACT FROM AUTHOR]

Near real-time prediction of earthquake-triggered landslides can rapidly forecast the spatial distribution of coseismic landslides just after a great earthquake, and provide effective support for emergency response. However, the prediction of earthquake-triggered landslides has always been a great challenge because of low accuracy and high false alarms. This work proposes a novel fuzzy deep learning (FuDL) model for near real-time earthquake-triggered landslide spatial prediction. Fuzzy learning theory is for the first time employed in earthquake-triggered landslide prediction. The FuDL has high generalization and robustness, effectively improving the accuracy of earthquake-triggered landslide prediction. Eighteen earthquake-triggered landslide inventories worldwide from 2008 to 2022 are employed to conduct ETL prediction. According to the chronological order, 15 earthquake-triggered landslides from 2008 to 2018 are adopted to train the FuDL model, and 3 earthquake-triggered landslides from 2019 to 2022 are utilized for near real-time earthquake-triggered landslide prediction. Furthermore, this work reveals that ground movement, relatively steep and high topography, and strong seismic intensity are critical factors affecting the spatial distribution of earthquake-triggered landslides. In addition, this work conducted a detailed analysis of the distribution patterns of earthquake-triggered landslides on a global scale. • A novel FuDL model is suggested and achieves high accuracy and good generalization. • FuDL model outperforms the state-of-the-art machine learning or deep learning models. • Topography, ground shake, and seismic intensity dominate the distribution of ETLs. [ABSTRACT FROM AUTHOR]

Seismic intensity measures at different levels significantly impact the seismic damage of building clusters. Reinforced concrete (RC) structures are a type of building widely used in different regions worldwide. A large amount of field seismic damage observation data indicates that within the same seismic intensity zone, the directional effects of varying ground motions lead to significant differences in damage to RC structures on different floors. However, relatively little research has been conducted on estimating the seismic fragility and vulnerability of RC structures considering the directional effects of seismic action. To further study the directional effect of seismic motion on the damage of different floors, this study conducted dynamic time history and spectral analyses on 1472,379 acceleration records in multiple directions obtained from monitoring at nine actual seismic stations during the 2008 Wenchuan earthquake in China. This paper innovatively reports on the actual damage features of RC structures during the Mw6.2 magnitude Jishishan earthquake in Gansu Province, China, on December 18, 2023 (the most severe destructive earthquake in China in 2023) and analyses the influence of earthquake directionality on the damage to different floors of RC structures. A three-dimensional numerical model of a four-story RC frame structure was established using numerical simulation and the finite element method. Different intensity measures were taken to input seismic excitations of different intensities into the RC structure in the 0°, 30°, 60°, and 90° directions, and damage simulation analysis was conducted. The nonlinear dynamic time history curves of structures under multiple directions of seismic excitation in different intensity zones have been developed. Using the interstory stiffness and interstory displacement angle as engineering demand parameters, damage assessment curves and stress clouds for RC structures with 1–4 floors considering different seismic directional effects were generated. The analysis results and major findings indicate that the seismic sequence in the 0° direction has a relatively heavy impact on the first floor of the RC structure in zone IX, which is consistent with the actual field observation results. • The structural failure caused by the most recent earthquake in China was reported. • This paper analyzes the influence of directional effects of ground motion on RC structures. • This paper uses empirical and numerical simulation methods to establish a structural damage model. [ABSTRACT FROM AUTHOR]

This paper presents a reliability analysis of concrete masonry infill walls with an aim to examine the efficacy of the resistance factor specified in the infill design under seismic loading. A numerical model for masonry infilled reinforced concrete frames was developed and encoded in OpenSees for this study. The model was validated using experimental data. Two features were involved in this reliability study, including 1) that the effect of spatially varying masonry compressive strength f ′ m on the lateral resistance of masonry infills was considered using the Random Finite Element Method, and 2) that seismic load with different return periods was considered to provide a more complete treatment of a reliability analysis. The study selected six Canadian cities with varying levels of seismic intensity for this analysis. By calculating the probability of failure of infill frames subjected to earthquake loading at different locations, the paper showed that the current resistance factor of 0.6 in the infill design equation suggested by the Canadian masonry design standard is conservative. To achieve a reliability index of 3, this factor could be increased to 0.65 for all cities studied. For cities with low seismicity such as Toronto, the results suggest that an even higher resistance factor is justified. • A meso-model encoded in OpenSees to simulate the in-plane behaviour of masonry infilled RC frames. • A reliability-based study on masonry infilled RC frames using the Random Finite Element Method (RFEM). • Considered spatially varied masonry compressive strength and seismic loads with varying return periods. • Calibrate the resistance factor specified in CSA S304-14 for the design of masonry infills. [ABSTRACT FROM AUTHOR]

Probability-based seismic risk and random ground motion theories are used to develop high-precision seismic risk functions and models of regional building portfolios. Seismic intensity measures and structural demand parameters are critical in developing seismic fragility models for building clusters. Earthquake damage data indicate that ambient temperature may influence structural fragility, but the effect of temperature on seismic risk is commonly ignored. A method for quantifying seismic intensity is proposed in this study and optimized using 450,000 acceleration records detected by 15 stations during the Luding earthquake in Sichuan, China, on September 5, 2022. Considering the influence of different temperature fields, the proposed seismic intensity quantification method was used to evaluate structural damage during two destructive earthquakes in Xinjiang, China (the Aktao earthquake on September 2, 2003 and the Zhaosu earthquake on December 1, 2003). Three structural empirical seismic risk matrices and cloud maps were developed, and a vulnerability membership curve was generated using fuzzy decision-making, a membership algorithm, and nonlinear regression. A structural seismic risk index function was proposed, and vulnerability cloud diagrams and curves based on actual structural seismic vulnerability datasets were generated. Together, these analyses demonstrated the impact of temperature and intensity measures on the seismic risk to regional buildings. A model was established to evaluate the seismic risk to typical structures and was validated using historical earthquake damage data from China. This method improves the accuracy of earthquake risk and vulnerability assessments for typical building clusters given the influence of temperature. The developed seismic risk prediction model enables the evaluation of vulnerability and resilience of typical structures under low and high temperatures. [ABSTRACT FROM AUTHOR]

This research is focused on the development and experimental validation of a novel double-stage yield steel slit damper-buckling restrained brace (SSD-DYB) system designed for seismic resistance of steel structures. The SSD-DYB integrates the energy dissipation capability of a steel slit damper (SSD) in its initial segment, enhancing performance in the case of lower seismic intensities levels while employing a larger segment for higher load resistance to maintain structural stability. The results of the study show that the proposed SSD-DYB is capable to reduce the weight of similar all-steel buckling restrained braces (BRBs) successfully addressing critical points through stiffeners and top and bottom plates. Additionally, the U-shaped element exhibits resilience during seismic loads, indicating its potential for replacing cores without failure which would be beneficial for seismic retrofitting of buildings. Experimental tests show that varying the number and shape of SSD strips significantly impacts the hysteresis curve's maximum load and dissipated energy (i.e., adding strips increased energy dissipation by 33.48 % for SSD-DYB-1), which can be used to control the proposed device for a specific performance target. Stopper mechanisms within the SSD-DYB regulate load distribution between segments and can be used to control the device and its transmitting capacities. Finally, an optimized SSD-DYB has been proposed with promising performance to be used by researchers for designing new structures or retrofit old ones. • Development and experimental validation of a novel double-stage yield steel slit damper-buckling restrained brace (SSD-DYB). • Number and shape of SSD strips significantly affect hysteresis curve's maximum load and dissipated energy (e.g., 33.48 %). • U-shaped element exhibits resilience during seismic loads and its potential can be used for replacing cores without failure. • An optimized SSD-DYB has also been proposed and experimentally validated with promising performance. [ABSTRACT FROM AUTHOR]

Modular construction is becoming more popular worldwide due to its reduced construction time, lower construction waste, decreased on-site labor requirements, among other benefits. However, the unique structural characteristics of modular buildings, such as discrete floor diaphragms, limited connections between modules, may result in different behavior during earthquakes compared to conventional buildings. However, the seismic response of modular buildings is not well understood, and the force demand in seismic collectors (i.e., connections between modules and seismic force resisting elements) is not quantified. To address this problem, a 9-story prototype building with reinforced concrete (RC) walls was used to investigate the structural properties and responses of modular buildings. Firstly, a nonlinear numerical model was created to accurately model the RC walls, modular frames, inter-module connections, seismic collectors, and other key structural elements. Elastic modal analysis and nonlinear response history analyses were conducted to assess the building's behavior under seismic loads. Subsequently, a simplified numerical model was developed to investigate the effect of three key parameters: the stiffness of seismic collectors, RC wall strength, and earthquake intensity. It was found that modular buildings with RC walls in the center are torsional flexible. Reducing the seismic collector's rigidity can lead to greater force response in the collector. The maximum forces experienced by seismic collectors at the first floor are sensitive to earthquake intensity but not significantly affected by the RC wall strength. Both an increase in the of RC wall strength and earthquake intensity can lead to an increase in the maximum forces experienced by seismic collectors. The method in ASCE 7–16 substantially underestimated the maximum acceleration coefficients at stories below 80 % of the structural height. • Nonlinear numerical model with discrete floor diaphragm and inter-module connection. • Modular building with RC walls in the center is torsional flexible. • Reduced rigidity of seismic collectors led to greater force response in them. • Both RC wall strength and earthquake intensity affect force in seismic collectors. • ASCE 7-16 substantially underestimate the maximum acceleration coefficients. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel sort of macrocyclic CQDs sensor from HemiQ[6] has been developed. • The CQDs sensors exhibited a highly sensitive and real-time response to Pb2+. • The CQDs suggested a potential application for the efficient determination of Pb2+. A macrocyclic compound, hemicucurbit[6]uril (HemiQ[6]), is employed as the carbon source to produce a novel sort of carbon quantum dots (CQDs) with blue fluorescence in aqueous solution. The CQDs are fully identified by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Nuclear Magnetic Resonance (NMR), zeta potential, ultraviolet/visible (UV–vis) and photoluminescence spectroscopy (PL). The nanomaterial is developed for the analysis of Pb2+ in the light of the Resonance Rayleigh scattering (RRS) changes with the increasing Pb2+ concentration. The proposed probe emerges a high selectivity to Pb2+ and excellent sensitivity in the linear concentration range of 0–6 μM with a detection limit low to 0.42 μM, which is superior to the previous values of Pb2+ sensors, as well as the good anti-interference ability is confirmed by the specifical response to Pb2+ in the presence of other metal cations. Therefore, the proposed analysis of Pb2+ is explored for the application in real samples of tap water and lake water, in satisfied results of acceptable recoveries. [ABSTRACT FROM AUTHOR]

The seismic fragility of prefabricated self-centering frame structures composed of self-centering joints is investigated for reference in their seismic design and application. In this paper, a new design of the concrete-filled double steel tubular column-RC beam joint with self-centering capability and friction energy dissipation was proposed. The joint was modeled with ABAQUS and OpenSees, and hysteretic simulation was carried out to verify the reasonableness and accuracy of the OpenSees phenomenological model. Based on the OpenSees platform, a one-bay, six-story prefabricated self-centering frame structure was modeled, and seismic fragility analysis based on the incremental dynamic analysis was performed, in which seismic fragility curves were obtained according to the probabilistic demand analysis model. The results indicated a high coincidence in hysteretic curves between the ABAQUS model and the OpenSees phenomenological model, which showed favorable self-centering and energy dissipation performance of the joint proposed in this paper. Based on FEMA 356, three kinds of performance points were defined, i.e., "Immediate Occupancy" (IO), "Life Safety" (LS), and "Collapse Prevention" (CP). The prefabricated self-centering frame in this paper tended to exceed the IO, where the stiffness and strength of the structure was susceptible to damage. However, the failure probability at the LS performance level remained low, with only 5% and 37% failure probability under moderate and rare earthquakes, respectively. The structure achieved a collapse margin ratio of 4.28, which indicated a high collapse resistance in it. • Established a phenomenological joint model based on SelfCentering Material model. • Derived lognormal distribution relationship between EDP and IM using linear regression. • Obtained failure probability of self-centering joint for CFDST under various seismic intensities through IDA. [ABSTRACT FROM AUTHOR]

• Non-linear finite-element modelling and time-history analysis of industrial racks. • Seismic fragility of unbraced steel pallet racks designed for gravity loads only. • Comparison of conditional rack fragility on PGA and S a associated with various EDPs. • Influence of the main structural parameters of racks on their seismic fragility. • Insights into pallet drop probability and damage propagation to btc connections. Past Italian earthquakes revealed the high seismic vulnerability of steel pallet racks designed for gravity loads only, which are still the most widespread industrial storage system. This study aims to derive the seismic fragility of these structures to enable more refined estimates of enterprise risk and the definition of effective retrofit solutions. For this purpose, 3D non-linear models of 27 unbraced pallet racks, representative of the Italian context, were analysed in Time-History under 268 bidirectional events, representative of Italian seismicity. Multiple fragility models were then derived, based on various engineering demand parameters and seismic intensity measures, through a cloud approach. [ABSTRACT FROM AUTHOR]

This paper presents an application of artificial neural networks (ANN) to ground motion modelling. We focused on developing a generalised ground motion model (GGMM) incorporating several seismic intensity measure (IM) types and their inter-IM correlation. These range from classical IMs, such as peak ground acceleration/velocity/displacement, spectral acceleration, and significant duration, to more advanced IMs recently shown to be better descriptors of structural performa nce, such as average spectral acceleration and filtered incremental velocity. Additionally, three different horizontal component definitions were included for the spectral acceleration-based IMs. A total of nine input ground motion causal parameters are required to use the GGMM developed, based on ground motion records from the NGA-West2 database. ANN was used to perform the regression, which differs from the approaches used in many existing ground motion models (GMMs), and gives the possibility to regress all IMs simultaneously in one model. A mixed-effects regression approach was adopted for the regression and the quantification of the inter- and intra-event variability of the GGMM estimation. The correlations between the IMs were also quantified and briefly presented here, which allows for a more refined prediction of seismic shaking and a unified treatment of prediction and IM correlations. This will allow more advanced record selection for non-linear dynamic analyses to be performed, which can consider several facets of ground shaking currently overlooked in many works. We evaluated the performance of the developed GGMM using several metrics and compared it to various existing GMMs developed with either the classical approach or machine learning methods. The results show that the proposed GGMM exhibits very good predictions, especially considering the wide range of IMs tackled. Lastly, this methodology has the flexibility of being able to add more IMs or horizontal component definitions seamlessly. This manuscript presents a novel generalised ground motion model for traditional and next-generation intensity measures (IMs) used in seismic hazard and risk. Some notable points: • Utilization of artificial neural networks to capture the complex interdependencies among multiple IMs. • The flexibility and accuracy of the model allows for more refined predictions for the next-generation IMs. • All the included IMs are simultaneously regressed using a mixed-effects regression procedure. • The proposed model can be used by the user to provide outputs of several IMs, which accommodates ease of use. • Correlations between the IMs were also quantified to offer a more consistent and unified treatment of IM correlations. • Comparisons of the developed model with existing models from the literature showed good performance and reduced dispersion. [ABSTRACT FROM AUTHOR]

A reliable estimation of maximum displacement demands of seismically isolated inelastic superstructures is crucial for assessment of base-isolated buildings under beyond-design earthquakes. Constant-strength inelastic displacement ratio, C R , spectra, as applied in the performance-based seismic assessment procedure, can be used to estimate the inelastic displacement demands of structures. Currently, a suitable analytical expression of C R is lacking for base-isolated structures considering the influencing parameters comprehensively. This paper seeks to fill this gap. The constant-strength spectra are computed from nonlinear dynamic analyses of simplified two-degree-of-freedom models considering the inelastic behavior of the superstructure and isolator system, using a set of earthquake ground motions recorded on stiff soil sites. The effects of strength reduction factor of superstructure, superstructure elastic period, secondary stiffness ratio of superstructure, mass ratio, isolation period, normalized strength of isolation system and superstructure viscous damping on the mean and dispersion of C R are investigated. In particular, the effects of variations in earthquake intensity and isolator strength on C R are taken into account by the normalized strength of isolation system. Besides, limiting values of C R as the superstructure elastic period tends to zero or infinity are discussed and verified using the statistical values of C R. Finally, based on the trends of C R with respect to the design parameters of the superstructure and isolation system, and the boundary conditions to the C R formula, an analytical estimating equation with reasonable accuracy is developed to approximate the mean constant-strength inelastic displacement ratios during seismic assessment of base-isolated building structures built on stiff soil sites. • Constant-strength inelastic displacement ratio, C R , spectra are constructed for inelastic base-isolated structures with LRBs. • Effects of earthquake intensity and isolator strength on C R are considered by normalized strength of isolation system. • Influence of superstructure viscous damping ratio on C R is evaluated. • Boundary conditions to C R formula are discussed and verified. • An analytical equation with reasonable accuracy is developed to predict C R. [ABSTRACT FROM AUTHOR]

Negative stiffness-incorporated dampers have been widely accepted as effective vibration mitigation systems for flexible structural stiffness adjustment and enhanced energy dissipation. However, current investigations and optimal designs of negative stiffness-incorporated structures are limited to the linear elastic assumption of primary structures, potentially causing stability issues and unsatisfactory control performance. In this case, this study derives the stability criterion for negative stiffness amplifying damper (NSAD)-incorporated nonlinear structures and establishes stability-oriented design as well as modification formulae. The theoretical foundation of NSADs and nonlinear primary structures are initially introduced, based on which the stability criterion is derived according to the Routh–Hurwitz stability criterion. Following the existing design of linear elastic assumption, an endurance time acceleration series is generated subsequently to examine the proposed stability criterion for NSAD-equipped nonlinear structures. Consequently, the stability-oriented design method and corresponding modification formulae are proposed for near-field and far-field earthquakes, of which the effectiveness is validated through design cases. The results underscore the importance of considering structural nonlinearity for ensuring stability and designing NSAD-equipped nonlinear structures, demonstrating the feasibility of using the proposed correction factors to guarantee the stability of NSAD-equipped nonlinear structures subjected to multi-type earthquakes with various intensities. Additionally, the established design framework successively provides a high-efficiency energy dissipation device for seismic control of nonlinear structures, simultaneously generating easy-to-use design formulae for NSADs by combining the linear structure-based design and modification factors, facilitating direct design of nonlinear structures. • Negative stiffness amplifying damper (NSAD) for nonlinear primary structures. • Modification factors of the negative stiffness ratio guarantee structural stability. • Stability-oriented design of NSAD with target performances of nonlinear structures. • Design formulae of NSAD combining linear structure design and modification factors. • Enhanced energy dissipation and robustness for nonlinear vibration mitigation. [ABSTRACT FROM AUTHOR]

The current Italian code "NTC2018" and Eurocode "EC8" provide specific design requirements in terms of flexural overstrength factors for reinforced concrete (RC) buildings in seismic areas. This study proposes to improve the design methodology by including explicitly the confinement effects within the seismic design of a new regular RC frame due to their influence on the capacity design principles (at structural and member level). Specifically, the seismic performance of a RC frame designed according to codes is compared, in reliability terms, with the one of the same frame designed including the concrete confinement effects. Moreover, a comparison between three constitutive models for confined concrete is performed. Selecting L'Aquila (Italy) as reference site, the two design methodologies combined with the three confinement models are numerically implemented. Scaling 30 non-frequent natural ground motions to increasing seismic intensity measures, according to the site seismic hazard, non-linear incremental dynamic analyses (IDAs) have been developed. Assuming the interstory drift indices as engineering demand parameters, the peak responses have been fitted through log-normal distributions to define IDA curves. Subsequently, appropriate limit state thresholds have been adopted to define the seismic fragility curves. Finally, through the convolution integral and Poisson model, the seismic reliability curves have been derived showing the importance of the proposed design methodology. In fact, for the frame under investigation, the seismic performance strongly improves in terms of ductility respecting all the reliability objective levels if the confinement effects are explicitly considered in the seismic design. Furthermore, the different confinement models provide similar results when the proposed seismic design is adopted, implying a reduction of the model uncertainty. • A novel seismic design methodology for new RC MR structures is proposed. • Concrete confinement effects are explicitly included through an iterative approach. • Three constitutive models for concrete confinement are adopted and compared. • IDA, seismic fragility and reliability curves are assessed for a 2D RC MR frame. • A reliability comparison between the standard and novel seismic design methodology. [ABSTRACT FROM AUTHOR]

Due to the gradual and constant accumulation of seismic energy, Peninsular India (PI) is typically considered seismically stable with low to moderate seismicity. The seismic studies in Peninsular India always resorted to synthetic ground motion simulations, because of the limited instrumentation and hence lack of recorded data. In the absence of a well-defined medium model for PI, the usual practice is to use simple site proxies or one-dimensional velocity structures for ground motion simulations. However, the region consists of multi-scale geometric complexities, significant topography, and sedimentary basins and is surrounded by deep oceans. Thus, the radiated seismic wave field in the region is influenced by the medium properties and in the absence of a well-defined tomography model the reliable estimation of seismic hazard is a challenging problem in PI. Therefore, the seismic wave propagation in PI can be investigated using numerical simulation with reliable 3D computational model for PI, incorporating the knowledge of the underlying Earth structure. Hence, the present study attempts to develop a sophisticated three-dimensional (3D) medium model of Peninsular India for physics-based ground motion simulations for regional earthquakes. This is aided by the availability of one-dimensional (1D) velocity models and the crustal structure from the receiver function analysis which provides valuable insight into the variation of material properties in the region. In the present study, >100 s of 1D velocity profiles are collected from various literature, which is then grouped under 23 different geological regions identified in PI (as per GSI (2000)). The averaged material properties are assigned per each geological region and the information on sediment depths, basin geometry, topography, and bathymetry are incorporated. We use the spectral element method (SEM) to calibrate our 3D computational model by simulating synthetic seismograms and comparing them to recorded ground motions for two past earthquakes: the 2001 Mw 7.6 Bhuj earthquake and the 1997 Mw 5.8 Jabalpur earthquake. Further, the seismic waveforms at the near field of 2001 Mw 7.6 Bhuj event are simulated using a refined regional model. The spatial variability of associated seismic intensities and peak ground velocity (PGV) amplification are investigated. In addition, a study of the impact of model depth truncation and sphericity on ground motion is also conducted. The implemented medium model is the first of its kind for Peninsular India and can reliably be used in seismic wave propagation studies in the region. The simulated outcomes from the model are of engineering importance as these results can be used for seismic hazard assessment of the region. [Display omitted] • A 3D computational model of Peninsular India is developed for physics-based ground motion simulations of regional earthquakes • The model incorporates lateral variation of material properties, topography, bathymetry and geographical features. • The developed model is validated by simulating ground motions for the 2001 Mw 7.6 Bhuj and the 1997 Mw 5.8 Jabalpur events. • The application of the model is demonstrated by simulating ground motions and estimating the seismic intensities at the nearfield of the 2001 Mw 7.6 Bhuj earthquake at the Kachchh basin. [ABSTRACT FROM AUTHOR]