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

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

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

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

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

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

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

A large-scale shaking table test of a living stump slope with a geometric similarity ratio of 1:7 was designed and completed. The peak acceleration, acceleration amplification factor, and displacement response patterns of living stumps slopes under different types of seismic waves and excitation intensities were obtained. The time-frequency and energy variation characteristics were analyzed using the Hilbert-Huang Transform (HHT). The results showed that: (1) Regardless of the type of seismic wave, the peak acceleration and acceleration amplification factor of the living stumps slope surface are positively correlated with relative height and seismic excitation intensity. When the excitation intensity is ≤ 0.4 g, the acceleration amplification effect is more pronounced; when the excitation intensity is > 0.4 g, the acceleration amplification effect weakens. (2) Under the action of different seismic waves, the peak displacement of slope surface shows amplification effect along the elevation, and increases with the increase of excitation intensity. In addition, the incremental displacement gradually decreases from the toe to the top of the slope, which is expressed as D2 > D3 > D1 > D4 > D5. The peak displacement at the top of the slope is the greatest, but the incremental displacement is the smallest; the peak displacement at the toe of the slope is the smallest, but the incremental displacement is relatively large. (3) Regardless of the type of seismic wave, living stumps slope shows the characteristics of filtering the low-frequency components of the seismic waves and amplifying their high-frequency components. At the same time, the seismic Hilbert energy gradually accumulates along the elevation. PSHEA and PMSA significantly increase with elevation and excitation intensity, and they reach the maximum at the top of the slope. (4) The seismic Hilbert energy is positively correlated with the relative height and excitation intensity, and reaches the maximum at the top of the slope. With the accumulation of seismic Hilbert energy increases, the dynamic response parameters such as peak acceleration, acceleration amplification coefficient and displacement also increase synchronously, reaching the maximum at the top of the slope. The research conclusions can provide an experimental basis for the seismic design of living stumps slopes. [ABSTRACT FROM AUTHOR]

Summary: A high‐strength steel framed‐tube structure with shear links fabricated using low‐yield‐point steel (HSSFTS‐LYPSL) was developed in this study to improve the seismic performance and resilience of the conventional steel framed‐tube structure. When this HSSFTS‐LYPSL is subjected to strong earthquake excitation, its shear links undergo significant plastic deformation to dissipate seismic energy while critical components such as the spandrel beams and columns maintain their elasticity. Furthermore, the replacement of damaged links was facilitated by the use of bolted end‐plate connections. This study designed three typical HSSFTS‐LYPSL examples with 20, 30, and 40 stories to investigate the seismic collapse performances of HSSFTS‐LYPSLs at different seismic intensity levels. Three‐dimensional nonlinear finite element analysis models of these example structures were developed using the OpenSEES software, and the accuracy and effectiveness of the modeling approach was validated by comparing its results with those of quasi‐static tests on sub‐structure assemblies. Next, 40 records each of far‐field and pulse‐type near‐field ground motions were selected and applied with an incremental dynamic analysis (IDA) to obtain response curves for the example structures and calculate their collapse fragility curves and collapse margin ratios (CMRs) utilizing a modified collapse fragility model. Finally, based on the collapse fragility and seismic hazard curves, the seismic collapse risk probability curves of the HSSFTS‐LYPSLs were obtained under far‐ and near‐field earthquakes, revealing that at the maximum considered earthquake level, the CMR values ranged from 5.74 to 7.25 and from 4.85 to 6.67, respectively; at the very rare earthquake (VRE) level, the CMR values ranged from 3.83 to 4.85 and from 3.24 to 4.46, respectively. These results demonstrate that HSSFTS‐LYPSLs exhibit sufficient potential for seismic collapse resistance. As pulse‐type near‐field earthquakes had more significant and adverse impacts on the seismic collapse performances of the HSSFTS‐LYPSLs than far‐field earthquakes, the seismic collapse design of an HSSFTS‐LYPSL should particularly consider the influence of near‐field effects. In addition, the seismic hazard function had a greater effect on the structural seismic collapse risk curves than the collapse fragility function, suggesting that seismic collapse risk curves could provide a comprehensive assessment of HSSFTS‐LYPSL seismic collapse performance. Under far‐ and near‐field earthquakes, the annual collapse risk probabilities of the HSSFTS‐LYPSL examples at the VRE level were within 1.18 × 10−5–4.53 × 10−5, which is below the seismic collapse risk threshold recommended by others, indicating that HSSFTS‐LYPSLs can meet the fourth‐level performance objective of "no collapse failure at the VRE level." However, this study only conducted seismic collapse and risk assessments using example HSSFTS‐LYPSLs; future research will focus on determining the seismic recovery capacities of and developing post‐earthquake repairability methodologies for HSSFTS‐LYPSLs. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Predictive models for spatial correlation play an effective role in the assessment of seismic risk associated with distributed infrastructure and building portfolios. However, existing models often rely on simplified approaches, assuming isotropy and stationarity. This paper verifies these assumptions by presenting a comprehensive study using a database of 3D physics-based simulated broadband ground motions for Istanbul, generated by the SPEED software. The results reveal significant event-to-event variability and nonstationary and anisotropic characteristics of spatial correlation influenced by source, path, and site effects. The development of nonstationary correlation models requires exploring influential metrics beyond spatial proximity and gaining a deep understanding of their impact, which is the focus of this study. Analysis of the spatial correlations of peak ground displacement, peak ground velocity, peak ground acceleration, and response spectral accelerations at different periods, employing both stationary and nonstationary correlation modelling methods and considering the finite fault model, indicates that the slip distribution pattern, direction and distance of station pairs relative to earthquake rupture, soil softness, and homogeneity of soil properties significantly influence the spatial correlations of near-field earthquake ground motions. Implementation of the introduced parameters in predictive spatial correlation models enhances the precision of regional seismic hazard assessments. [ABSTRACT FROM AUTHOR]

Current seismic design codes for bridge structures do not account for the influence of aftershock sequences, which, to some extent, overestimate the seismic performance for bridges subjected to mainshock‐aftershock (MS‐AS) scenarios. To address the great need for ground motion sequences tailored to specific research sites for fragility analysis, this study proposes a method for generating artificial MS‐AS ground motion sequences based on the evolutional bimodal Kanai–Tajimi model and the Epidemic–Type Aftershock Sequence model. We establish a framework for MS‐AS fragility analysis using an input–output Hidden Markov Model (IOHMM), where the damage states (DS) of bridge piers are considered unobservable and are inferred statistically through damage indices in an unsupervised manner. Model parameters are trained using intensity measure (IM) sequences and damage index (DI) sequences. Fragility curves for both the mainshock and state‐dependent aftershocks considering multiple aftershocks are formulated based on the initial state probability and state transition probabilities of the proposed IOHMM. The fragility analysis results reveal that as the initial seismic damage level increases, the probability of aftershocks causing higher damage levels in the structure also increases, highlighting the significant impact of aftershocks on structural damage increments. Furthermore, we extend the proposed model to a bivariate seismic intensity measure and develop fragility surfaces. The proposed framework provides a novel approach and insights for tackling seismic fragility under multiple aftershocks. [ABSTRACT FROM AUTHOR]

Machine learning (ML) approaches, widely used in civil engineering, have the potential to reduce computing costs and enhance predictive capabilities. However, many ML methods have yet to be applied to develop models that accurately analyze the nonlinear dynamic response of cross-fault hydraulic tunnels (CFHTs). To predict CFHT models and fragility curves effectively, we identify the most effective ML techniques and improve prediction capacity and accuracy by initially creating an integrated multivariate earthquake intensity measure (IM) from nine univariate earthquake IMs using principal component analysis. Structural reactions are then performed using incremental dynamic analysis by a multimedium-coupled interaction system. Four techniques are used to test ML–principal component analysis (PCA) feasibility. Meanwhile, mathematical statistical parameters are compared to standard probabilistic seismic demand models of expected and computed values using ML-PCA. Eventually, multiple stripe analysis–maximum likelihood estimation (MSA-MLE) is applied to assess the seismic performance of CFHTs. This study highlights that the Gaussian process regression and integrated IM can improve reliable probability and reduce uncertainties in evaluating the structural response. Thorough numerical analysis, using the suggested methodology, one can efficiently assess the seismic fragilities of the tunnel by the predicted model. ML-PCA techniques can be viewed as an alternate strategy for seismic design and CFHT performance enhancement in real-world engineering. [ABSTRACT FROM AUTHOR]

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

Ancient timber structures have a high cost for conducting dynamic time-history response analysis due to the presence of many nonlinear components, such as mortise-tenon joints and Dou-Gon. To enhance the efficiency of evaluating the seismic performance of ancient timber structures through dynamic analysis, a simplified dynamic response analysis method based on SPO2IDA was adopted to evaluate the seismic performance of a timber frame palace with nine-purlin in Qing Dynasty of China and the results were compared with those obtained using the traditional pushover analysis method. The results showed that there were only slight differences in the seismic response of the ancient timber structure determined by the two methods when the structure was in a nonlinear stage. During a Ⅸ degree rare earthquake, the displacement response differed by 0.004 m, while the median seismic intensity during the third level of damage limit state differed by 0.079 g. The traditional pushover analysis method may underestimate the seismic resistance of the ancient timber structure, but the SPO2IDA algorithm can better capture the uncertainty of the structural vulnerability model at different limit stages caused by ground motion input, achieving the goal of quickly evaluating the seismic performance of the ancient timber structure with acceptable accuracy. [ABSTRACT FROM AUTHOR]

The MS6.2 earthquake occurred in Jishishan, Gansu Province, China, on December 18, 2023. Based on some strong seismic acceleration time histories captured by some stations of China National Strong Earthquake Observation Network and National Earthquake Early Warning Network, the spatial distribution characteristics, rupture directivity effect, hanging wall and footwall effect, response spectrum characteristics, and attenuation of the peak ground acceleration (PGA) were analyzed in this paper. It can be used as reference for the site determination of post‐earthquake reconstruction and seismic design of engineering structures. The analysis shows that the spatial distribution of strong ground motion of the Jishishan MS6.2 earthquake is mainly controlled by the distribution of causative fault. Near the fault, the effect of rupture directivity is obvious. The effect of hanging wall and footwall significantly affects the distribution of PGAs for this earthquake, causing a pronounced asymmetric pattern about PGAs relative to the fault, with slower attenuation on the hanging wall compared to the footwall. The type of site obviously affects the characteristics of response spectrum. The ground motion intensity observed at the epicenter of this earthquake significantly exceeded the levels of rare and extremely rare seismic events in the current seismic design codes. The attenuation relationship of PGA obtained by regression analysis shows that ones in the 5th generation Chinese ground motion parameter zoning map for the Qinghai‐Tibet region underestimate the horizontal PGA. [ABSTRACT FROM AUTHOR]

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

Beam bridges, as the primary structural form of medium and small-sized bridges, are extensively utilized for road and railway crossings over rivers and valleys. Ensuring their reliability during earthquakes is crucial not only for maintaining traffic flow but also for mitigating the seismic impact on the economy and society. Considering earthquake intensity and uncertain parameters, this paper proposes an innovative method for assessing the seismic reliability of simply-supported beam bridges under three different levels of seismic design: minor, moderate, and major earthquakes. The proposed method first estimates the probability of encountering three typical earthquake intensities during the design life of simply-supported beam bridges based on crowd intensity, benchmark intensity, and major earthquake intensity. It then introduces uncertain parameters and employs the point estimation method to calculate the probability of bridge passage under specific earthquake intensities. Finally, it combines these earthquake intensities to calculate the overall seismic reliability of simply-supported beam bridges. The effectiveness and efficiency of this method are demonstrated through calculations for a three-span, double-degree-of-freedom simply-supported beam bridge, and validated using Monte Carlo simulations. This research provides solid theoretical support for seismic assessment, design, and intensity-based reliability analysis of simply-supported beam bridges. [ABSTRACT FROM AUTHOR]

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

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

Past major earthquakes have demonstrated that a significant proportion of existing residential buildings are vulnerable to seismic hazards, resulting in economic and social losses. The assessment of earthquake‐induced losses is crucial for devising strategies aimed at enhancing seismic resilience through mitigation plans and emergency response measures. This study intends to provide an analytical methodology for evaluating economic losses for existing residential concrete shear wall buildings in Eastern Canada seismic zones based on Canadian‐compatible seismic capacity parameters. A sampled data set related to residential buildings in Montreal was analyzed and statistical distributions were developed that represent the proportion of buildings in different seismic design code levels and number of stories. Vulnerability analyses were performed, which involved estimating buildings' response under seismic hazard inputs according to the 2020 National Building Code of Canada and conducting loss assessment for structural components, nonstructural displacement‐sensitive components, nonstructural acceleration‐sensitive components, and contents. The results of vulnerability analyses in terms of loss ratio curves showed that the seismic performance varies between mid‐rise and high‐rise concrete shear wall buildings with different seismic design code levels, and nonstructural displacement‐sensitive components exerted the most significant influence on overall economic losses among building components. In addition, a comparison was conducted between Canadian‐compatible economic loss ratio curves and those developed based on the standard seismic capacity parameters in the Hazus technical manual and differences in predicted loss ratios were discussed. The developed loss ratio curves can be integrated into regional scale loss assessment tools for rapid estimation of earthquake‐induced economic losses for concrete shear wall buildings as a function of seismic intensity. [ABSTRACT FROM AUTHOR]

Rocking walls can control the overall deformation pattern and the distribution of plastic energy dissipation in structures, suppressing the occurrence of weak layers. In the case of step-terrace frame structures, issues such as severe lateral stiffness irregularities, abrupt changes in floor-bearing capacity, and concentrated deformation in upper ground layers exist. To improve the yielding and failure modes of step-terrace frame structures in mountainous regions, this paper proposes a structural system combining step-terrace frame structures with energy dissipation rocking walls attached to their bottoms, aiming to control the yielding mechanism of the structure, further reduce the seismic response, limit residual deformation, and propose a structural system of step-terrace frame structures with buckling-restrained braces (BRBs) and energy dissipation rocking walls. Two sets of numerical models for step-terrace frame structures with different numbers of dropped layers and spans were established. Through simulating low-cycle repeated loading tests on step-terrace frame structures, the rationality of the models and parameters was verified. Incremental dynamic analysis (IDA) was employed to systematically investigate the vulnerability of step-terrace frame structures with energy dissipation rocking walls under different dropped layer and span configurations. This investigation covered aspects such as IDA curve clusters, percentile curves, seismic demand models, fragility functions, failure state probabilities, vulnerability indices, collapse resistance factors, and safety margins. The results indicated that the change in dropped layer numbers had a far greater impact on the vulnerability of step-terrace frame structures with energy dissipation rocking walls than the change in dropped span numbers. Under seismic excitations with the same peak ground acceleration (PGA), rocking walls can limit the depth of structural plasticity development, reduce the dispersion of peak responses, and lower the probability of exceeding various performance levels, thereby exhibiting good collapse resistance. The addition of buckling-restrained braces (BRBs) can further enhance the seismic performance and collapse resistance of the rocking wall frame structure. By analyzing the correlation between seismic intensity measures and peak structural responses, the validity of using peak ground acceleration as a scaling indicator for incremental dynamic analysis (IDA) has been verified. [ABSTRACT FROM AUTHOR]

This paper investigates a method for improving the selection of seismic motions for designing earthquake-resistant underground structures. It is found that PGV alone is unreliable as a predictor of structural damage with increasing earthquake intensity. Therefore, based on characterizing seismic intensity by using PGV, another parameter, referred to here as "the severest parameter", is introduced to distinguish potential damage capacity for different seismic motions. A numerical model of a soil–underground structure system was established using the finite element software OpenSees. A total of 120 real ground motions were selected for the model, considering the influences of eight different site groups on the underground station and the rupture distances of the input seismic motions. The results show that as seismic intensity increases, substantial variability in the response of underground structures emerges under the same amplitude of PGV, diminishing the effectiveness of the relationship between PGV and structural damage. When assessing the potential damage capacity of seismic motions with similar or close amplitudes of PGV, VSI is an appropriate severest parameter for Class III sites and ASI is suitable for Class II sites. When the correlation coefficient between the severest parameter and the structural response is greater than 0.8, it can be used to reliably assess seismic damage capacity based on the size of the severest parameter. [ABSTRACT FROM AUTHOR]

Current seismic structural design makes use of a ground motion intensity that has a certain probability of being exceeded at a site of interest in a time interval or, equivalently, exceedance return period. The design intensities with the same return period are often collected in the form of maps deriving from probabilistic seismic hazard analysis (PSHA) for each of the sites of interest. Probability theory underlying PSHA dictates that, in any time interval, design intensities are expected to be exceeded in a fraction of sites that depends on the return period the map refers to. In the case of Italy, three different nationwide PSHA studies can be currently considered of relevance. In the study, the estimated areal fraction of the Italian territory exposed to exceedance of the design intensity from 2008 to 2019 was quantified for the three hazard models, based on ShakeMap data for instrumental earthquakes. In addition, the same fraction was calculated considering a sparse catalog of inferred ShakeMap for historical earthquakes that occurred over almost 1000 years. It was found that, despite the apparent differences in the hazard models, the estimated fraction of territory exposed to exceedance is comparable for all the considered hazard maps. [ABSTRACT FROM AUTHOR]

Ground-motion intensity measures (IMs), which quantify and describe the characteristics of earthquake ground motion, are of utmost importance in the assessment of seismic risk and the design of resilient structures with large spans. The appropriate selection of a ground-motion IM is crucial in establishing a reliable and robust correlation between seismic hazards and structural demands. The current study presents a novel ground-motion IM that incorporates the influence of multiple vibration modes and period elongation resulting from isolation based on the velocity spectrum. A comprehensive study has been conducted to examine the efficiency of 37 different ground-motion IMs on a roof-isolated large-span structure with engineering demand parameters (EDPs), using far-field ground-motion data. The initial examination of the proposed intensity measure involves a planar lumped-mass model. Subsequently, a numerical model of a large-span roof-isolated structure, specifically the Beijing Workers' Stadium, is constructed and examined. The results suggest that the proposed intensity measure (IM) demonstrates satisfactory adequacy and achieves optimal efficiency when considering three different engineering demand parameters among 37 other ground-motion intensity measures. [ABSTRACT FROM AUTHOR]

There has been no consensus on post‐earthquake operating plan for high‐speed railway trains. In this paper, two three‐dimensional coupling model of track‐bridge system without and with trains for high‐speed railways were developed, and their performance were verified based on shaking table tests. The equivalent method of design seismic track irregularity for random structures was discussed, and the amplitude response spectra of design seismic track irregularity for all levels of seismic intensity were proposed. In addition, the rationality of design seismic track irregularity was evaluated based on engineering case analysis, providing a theoretical foundation of formulating post‐earthquake contingency plans for high‐speed railways. The results show that when span number increases, the design seismic track irregularity amplitude increases and then tends to be stable; when the span number reaches 9, the train dynamic response gradually becomes stable; the random structures with arbitrary span numbers are equivalent to a specific 9‐span structure when constructing design seismic track irregularity. When the seismic intensity is low, there is no significant difference in shape and amplitude between the measured pre‐earthquake and post‐earthquake track alignment irregularities, and the train can normally run with no significant deceleration required. The train dynamic response under the design post‐earthquake track irregularity is greater than that under the measured post‐earthquake track irregularity, indicating that the design seismic track irregularity has a reasonable safety margin and a good feasibility in engineering practice. [ABSTRACT FROM AUTHOR]

This manuscript investigates the bias introduced by scaling aftershock ground motions when evaluating the performance of structures subjected to earthquake sequences. The study focuses on different hysteretic behaviors exhibited by structures and selects eight intensity measures as scale indicators. A benchmark database comprising 274 recorded mainshock–aftershock ground motions is utilized for analysis. The findings reveal that scaling aftershock records using intensity measures such as SI (seismic intensity), PGV (peak ground velocity), IC (Arias intensity), and Sa (spectral acceleration) relative to mainshock records effectively controls the mean bias within 30% throughout the entire period range, given a maximum scale factor of 10.0. However, it is observed that the additional damage in systems exhibiting un-degrading hysteretic behavior is more significantly affected by aftershock ground motion scaling compared to systems with degrading hysteretic behavior. Furthermore, scaling aftershock ground motions upwards using relative Sa tends to overestimate the additional damage incurred by structures. These results emphasize the importance of considering the specific hysteretic behavior of structures when applying aftershock ground motion scaling, as well as selecting appropriate intensity measures for accurate evaluation of structural performance. [ABSTRACT FROM AUTHOR]

The code-based response modification factors are mainly developed based on engineering judgments and experiences from past earthquakes, and hence, they may not lead to reliable solutions considering different performance targets and hazard levels. On the other hand, the uncertainties associated with these proposed values are more significant for new lateral load-carrying systems, such as tunnel-form buildings, due to insufficient information about their performance against seismic events. To address these challenges, this study aims to propose a multi-level approach for the estimation of response modification factors for tunnel-form building structures by taking into account the site seismicity and the damage level defined as the target performance. Using the proposed approach, the modification factors corresponding to different ranges of earthquake intensity and damage levels are obtained for 2-, 5-, 7-, and 10-storey tunnel-form buildings. The results are then used to verify the efficiency of the response modification factors proposed by design codes for the preliminary design (code-based factors) of such systems. It is shown that, in general, by adopting a response modification factor between 4 and 6, the tunnel-form structural systems exhibit excellent seismic performance and can satisfy the requirements of the Immediate Occupancy (IO) performance level even under the Maximum Considered Earthquake (MCE). The outcomes of this study could be useful for performance-based design of tunnel-form building structures aligned with the new generation of seismic design codes. [ABSTRACT FROM AUTHOR]

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

This paper presents the results of an experimental program involving shake table testing of two full-scale reinforced concrete frame buildings. These tests were conducted to investigate the effectiveness and reliability of a newly proposed servo-hydraulic Active Mass Damper (AMD) that can be designed to enhance the target seismic performance of a building at multiple earthquake intensity levels. The two nominally identical case-study buildings were intentionally designed to exhibit a "soft story" mechanism at the first level when subject to ground shaking of sufficient intensity, but one was equipped with the newly proposed AMD, installed on the roof. The two specimens were then subject to the same loading protocol consisting of a ground shaking sequence of varying intensity, with the seismic input consisting of a selected natural ground motion.The experimental results demonstrated that the proposed AMD is extremely effective at enhancing building seismic performance. Specifically, the AMD provided peak displacement reductions in the order of 70% and was shown capable of absorbing more than 60% of the total input energy. As a consequence, the un-retrofitted structure suffered nontrivial structural and non-structural damage, while the AMD-retrofitted building remained virtually undamaged at all shaking intensities considered. [ABSTRACT FROM AUTHOR]

The performance-based seismic design pretends to take care of the lives of the occupants and reduce the cost of damage caused by earthquakes. Several ways of estimating damage and economic losses have been developed, but most of them lack objectivity and have great dispersion in the results. In the last decade, the advancement of technology has allowed the appearance of new methodologies, such as the one developed by the Pacific Earthquake Engineering Research Center (PEER methodology). However, the information regarding application and scope is scarce. In the present investigation, the economic seismic performance for a steel building was determined by applying the PEER methodology with different levels of seismic intensity. A multi-family residential model of special moment frames (SMF) was used, and the structure was designed by means of modal analysis. Spectral, incremental dynamic non-linear analysis was performed where the structural response was determined, with the help of the PACT software. The seismic performance, expressed as the repair costs, repair times, deaths, and injuries, was defined. The results obtained indicate that buildings designed with traditional structural standards can be demolished after the action of an earthquake because the repair costs exceed 40% of the replacement cost. Rare and very rare seismic events can cause the total suspension of the service and a considerable number of deaths and injuries. [ABSTRACT FROM AUTHOR]

Accurate and rapid assessment of seismic intensity after a destructive earthquake is essential for efficient early emergency response. We proposed an improved method, AL-SM99, to assess seismic intensity by analyzing aftershock sequences that occur within 2 h of mainshocks. The implementation effect and application conditions of this method were illustrated using 27 earthquakes with Mw 6.5–8.3 that occurred globally between 2000 and 2023. When the fault system in the seismic region is clear and simple, the robust LOWESS-fitted (locally weighted regression program) curves could be used to estimate the location and length of the fault rupture. LOWESS results can indicate the overall rupture trend and make reliable rupture-scale judgments even when the fault system is complex. When Mw ≥ 7.0 and the number of aftershocks exceeds 40, the AL-SM99 intensity evaluation results may be more reliable. Using aftershock catalogues obtained by conventional means allows for a stable assessment of seismic intensities within 1.5 h of the mainshock. When the number of aftershocks is sufficiently large, the intensity assessment time can be greatly reduced. With early accessible aftershocks, we can quickly determine the rupture fault planes and have a better estimate of the seismic intensities. The results of the intensity assessment provide a useful guide for determining the extent of the hardest-hit areas. By expanding the data sources for seismic intensity assessment, the early accessible data are utilized adequately. This study provides a valuable reference point for investigating the relationship between early aftershock events and fault rupture. [ABSTRACT FROM AUTHOR]

During intense ground motion excitations, the pounding between adjacent buildings may result in extensive structural damage. Despite the provision of regulations regarding the minimum separation gap required to prevent structural collisions, the majority of existing structures are poorly separated. The modern seismic design and assessment of structures are based on the definition of acceptable response levels in relation to the intensity of seismic action, which is usually determined by an acceptable probability of exceedance. From this point of view, the seismic performance of a typical eight-storey reinforced concrete (RC) frame structure is evaluated in terms of pounding. In particular, the performance is evaluated using six different separation gap distances as a fraction of the EC8 minimum distance. As the height of the adjacent structure affected the required separation distance, the examined RC structure was assumed to interact with four idealized rigid structures of one to four storeys. The typical storey height was equal between the examined structures; therefore, collision could occur at the diaphragm level. To this end, incidental dynamic analyses (IDAs) were performed, and the fragility curves for different limit states were obtained for each case. Finally, the seismic fragility was combined with the hazard data to evaluate the seismic performance probabilistically. [ABSTRACT FROM AUTHOR]

Lessons from recent earthquakes have provided a tough reality check of the traditional seismic design approach and technologies, highlighting the urgent need for a paradigm shift of performance‐based design criteria and objectives toward low‐damage design philosophy and technologies for the whole building system. Modern society is asking for "earthquake proof" resilient buildings that are able to withstand seismic events without compromising their functionality. The EU‐funded SERA (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe Project) project discussed in this paper provided the opportunity to develop and validate within the European context an integrated seismic low‐damage prototype, including main structure and non‐structural elements, for the next generation of high‐performance buildings. This paper presents an overview of the research, involving three‐dimensional shake table tests of a two‐storey 1:2 scaled timber‐concrete post‐tensioned dissipative low‐damage structure "dressed" by earthquake‐resistant gypsum/masonry partitions and glass/concrete facades. Specimen details, construction and assembly phases, test setup, and experimental results are discussed. After many cycles of input motions at increasing levels of seismic intensity (higher than Collapse Prevention Limit State), the integrated building system exhibited a very high seismic performance. The experimental campaign carried out at the National Laboratory of Civil Engineering in Lisbon confirmed the unique potential of low‐damage technologies and the opportunity for their widespread implementation into design practice. [ABSTRACT FROM AUTHOR]

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In the context of performance‐based earthquake engineering (PBEE), response‐history analysis is currently considered an analytical tool for developing fragility curves. Typically, this involves subjecting a structural system to a large number of ground motion records (GMRs) representing seismic hazards at a site of interest and may be a time‐consuming task. To address this computational challenge, this study proposes a method for selecting a representative subset of GMRs that enables the reproduction of the fragility curve of the general GMR set. In this method, dimension reduction techniques are used to preferentially extract the principal features of earthquake intensity measures, which are applied to construct the feature space. Then, the divisive hierarchical clustering technique is applied to the feature space to obtain a subset of GMRs from the general set until the fragility curve converges. The performance of the proposed method is successfully demonstrated through various numerical examples that include a wide class of single‐degree‐of‐freedom systems and two steel‐frame buildings. The results confirm that the seismic hazard at a given site represented by a general GMR set can be covered in structural fragility estimation using a representative subset of GMRs selected based on the proposed method. The proposed method could contribute to significantly reducing the computational costs for structural fragility estimation without compromising the accuracy. [ABSTRACT FROM AUTHOR]

Buckling-restrained braces (BRBs) have shown their capability to provide building structures with stiffness, strength, and ductility. Estimating the seismic drifts of buckling-restrained braced frames (BRBFs) is an important design step to control structural and non-structural damage. In current practice of seismic design, the estimation of seismic drifts of BRBFs is performed by using empirical calculations that are independent upon either the type of the structural system or the design level of seismicity. In these empirical calculations, the seismic drifts are estimated by amplifying the reduced elastic drifts obtained under design lateral loading with a displacement amplification factor (DAF). The value of DAF is considered equal to the product of the response modification factor R and the inelastic displacement ratio ρ. The goal of the current research is to assess the value of ρ for low- to mid-rise BRBFs designed under low and high levels of seismicity. This goal has been achieved by conducting a series of elastic and inelastic time-history analyses pertaining to an ensemble of earthquake records on 3-, 6- and 9-story BRBFs. The results indicate that the ρ-ratio increases with an increase in design seismic intensity and an increase in experienced inelasticity. The range of ρ for low seismicity designs ranges from 0.63 to 0.9, while for high seismicity designs this range stretches from 0.83 to 1.29. It has been found that the consideration of a general ρ-ratio of 1.0 is a reasonable estimation for the design of the BRBFs considered in this study. [ABSTRACT FROM AUTHOR]

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

Single-column elevated station structures are irregular structures with long-span cantilever beams and individual pier columns in the transverse section. The uneven mass and stiffness in the horizontal and vertical planes necessitate research on the seismic performance of these structures. This study performed a nonlinear response-history analysis (NRHA) of a single-column elevated station structure using the finite element program MSC.MARC and analysed its seismic performance under different seismic intensities. The stress states of the primary components were evaluated, and the effect of vertical earthquake motion on the seismic performance of the structure was considered. The torsional behavior caused by the uneven mass and stiffness in both horizontal and vertical directions should be considered, and energy dissipation measures should be taken to reduce the internal force and deformation of the bottom-pier columns and second-floor columns in the process of designation to improve the seismic performance of the structure. A bidirectional pushover analysis (BPA) was applied. The load amplification factor was adjusted to optimize the BPA results. The results of the modified BPA were similar to those of the NRHA, indicating the computational reliability of the modified BPA. The modified BPA method was accurate, applicative, and efficient. The BPA can improve computational efficiency compared to NRHA and can be widely applied in the structural design process for practical engineering applications. [ABSTRACT FROM AUTHOR]

The present work aims to assess the large-scale seismic vulnerability of a set of 55 reinforced concrete educational establishments of different typologies (approximately 516 constructions) located within the urban perimeter of the city of Mostaganem. Among them, 328 buildings were constructed in accordance with the Algerian seismic regulation (built after 1980), while 188 constructions were built without a seismic design code (built before < 1980). This classification corresponds to the application/creation of this regulation following a major earthquake in Chlef (El Asnam) in 1980. Using the RISK-UE lm1 method, the vulnerability index was assessed based on a visual inspection for each building using an on-site inventory form to determine the general sources of seismic vulnerability. This strategy allows the prioritization of constructions according to their typologies, considering the structural system of the building and modifying factors, such as code level, maintenance condition, number of floors, plan and elevation irregularities, soil morphology, etc. The application of this methodology generated several seismic scenarios expressing the probable damage to the constructions, and the following results were suggested: The first two seismic scenarios have no damage corresponding to intensities I = 5; 6. The third scenario is characterized by low to negligible damage corresponding to intensity I = 7. Moderate damage was observed for the fourth seismic scenario (I = 8), while the fifth scenario generated by seismic intensity I = 9 presents moderate to heavy damage. The sixth scenario, with intensity I = 10, exhibits a relatively heavy damage balance. Starting from intensity I = 11, the damage becomes heavy to very heavy for the seventh scenario. Finally, the eighth scenario describes total destruction of the constructions. The results obtained from the application of this methodology on the educational buildings have been integrated into a Geographic Information System (GIS) environment to better understand the seismic behavior of the structures and to estimate the magnitude of seismic risk. This facilitates simulation and enables efforts to be made to take concrete preventive measures to strengthen existing educational buildings, thus reducing the negative impact of future earthquakes. [ABSTRACT FROM AUTHOR]

For buildings that meet the requirements of current seismic design codes, damage to nonstructural components and the internal objects of buildings often become the main source of the seismic economic losses of these buildings. However, the current specifications only consider the safety of 'no collapse under strong earthquake' and do not consider 'functional recoverability'. In this paper, a six-story frame building was taken as an example. Four joint performance limit states were proposed, as per FEMA 273, to establish a two-dimensional probabilistic seismic demand model that considers parameter correlations. The limit state function was established, and the two-dimensional seismic vulnerability curve was calculated. The seismic intensity–economic loss curve and the annual average economic loss established by one-dimensional and two-dimensional seismic vulnerability curves were compared. The results showed that the seismic performance of the structure was lower than expected when using only a one-dimensional seismic vulnerability curve. However, the situation was more serious under high-intensity earthquake and high-performance levels. [ABSTRACT FROM AUTHOR]

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Due to technological developments in last decade, new methods of seismic evaluation are in use like simulation based, algorithm based, probabilistic, software based etc. These developments have enabled researchers to move from linear to non-linear methods of analysis. Incremental dynamic analysis (IDA) is performance evaluation method where a suite of ground motions applied to structure are further scaled to particular levels of seismic intensity. Seismic fragility curves become significant in estimation of structures risk possibility from the point of view of potential earthquakes and helps in predicting the economic consequences for forthcoming earthquakes. The paper reflects IDA and seismic fragility analysis of ground storey + 7 floor (G + 7) reinforced concrete frame subjected to suite of eleven ground motions. Primary objective was to perform equivalent static and linear-dynamic analysis to meet the National and International codal requirements. Then, pushover analysis is carried out by introducing parametric auto hinges as per ASCE 41-13 tables. To carry out pushover analysis, both geometric and material non-linearity was introduced. Strong ground motions were selected as per suitable criteria of seismic intensity. IDA is then carried out as per SeismoStruct 2022 software and using IDA curves, the fragility analysis was carried out. The results of study found useful for researchers to predict the probability of damage of the structure under earthquakes. [ABSTRACT FROM AUTHOR]

The construction of high-speed railways continues to extend in seismic prone areas, but there is limited research on the seismic-induced track irregularities occurred in positions where high-speed railway bridges are involved. Taking a five-span high-speed railway simply supported beam bridge as the engineering example, the corresponding nonlinear system model, with CRTS II slab ballastless track, is established by using ANSYS finite element analysis software. The distribution mode of post-earthquake track residual irregularity is studied, the statistical characteristics of its power spectral density are analyzed, and a representative seismic-induced track geometric irregularity spectrum is constructed. The effects of the site categories and the epicenter distance on seismic-induced track spectrum are also discussed. The results show that after the earthquake, the alignment irregularity is significant, while the vertical, cross-level and gauge irregularities can be ignored. The amplitude of track geometric irregularity, caused by earthquake, increases significantly with the increase of ground motion intensity. The seismic-induced track spectrum obeys lognormal distribution at all frequencies. The track spectra almost coincide for all five site categories, thus, the impact of site categories on the seismic-induced track spectrum of high-speed railway bridges is considered negligible. Due to the pulse effect, the seismic-induced track spectrum of near-field earthquakes is significantly larger than that of far-field earthquakes. [ABSTRACT FROM AUTHOR]

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