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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]

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 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]

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]

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]

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]

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]

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]

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]

Self-centering beam-to-column connections (SBCs) were widely investigated to enhance conventional steel moment-resisting frame's (MRF's) post-earthquake repairability by reducing residual displacements. The peak displacement-targeted design methodology was adopted to develop the design guidelines for enhancing MRFs with the emerging self-centering members, where the desired post-earthquake repairability of the enhanced MRF needs to be achieved with inevitable iterative dynamic analyses. This paper intends to develop a novel post-earthquake repairability-based methodology for enhancing MRFs with SBCs, where residual and peak displacements are both targets. To this end, artificial neural network (ANN) models were developed to estimate the peak and residual displacements of the enhanced MRFs with SBCs under given seismic intensities. Peak and residual displacement-based design (PRBD) procedures were developed based on the proposed post-earthquake repairability-based methodology and established ANN models. Four design cases were designed through the developed PRBD procedure and analyzed. The design and analysis outcomes demonstrate that the improved MRFs can attain the intended post-earthquake repairability and meet the peak and residual displacement objectives without necessitating iterative design and dynamic analyses. This confirms the effectiveness and precision of the proposed post-earthquake repairability-based approach and PRBD procedure. Moreover, the enhanced MRFs with partially self-centering behavior achieved nearly zero residual displacements (lower than 0.2%) under maximum considered earthquakes. This finding shows that the partially self-centering MRF is a more cost-efficient solution for developing seismic resilient MRF than fully self-centering MRF to achieve excellent post-earthquake repairability with a lower requirement of self-centering capacities. • Post-earthquake repairability-based design methodology was proposed. • PRBD procedures were developed for enhancing MRFs with SBCs. • The enhanced MRFs can achieve the desired post-earthquake repairability without iterative design and dynamic analyses. • The enhanced MRFs with partially self-centering behavior can achieve nearly zero residual displacements under MCE. [ABSTRACT FROM AUTHOR]

The seismic response analysis of subway underground structures only considers the impact of a single mainshock, ignoring the aftershocks, which may cause more serious secondary damage within a short time after strong earthquakes. To investigate the seismic performance of underground structures under sequential earthquakes and improve the understanding of aftershocks, we analyzed the dynamic response of subway station structures under mainshock–aftershock sequences. A typical two-story and three-span subway station was selected as the prototype, and a finite element model of a soil–underground structure interaction was established. Based on the basic concept of endurance time and design response spectrum of relevant seismic standards in China, an endurance time acceleration function was generated, and nine mainshock–aftershock sequences were constructed. Thereafter, the seismic responses of subway stations under the action of mainshock–aftershock sequences, such as lateral deformation characteristics and damage failure law, were discussed and analyzed. The results show that the endurance time method can be used as a new and efficient method to study the seismic performance of underground structures subjected to mainshock–aftershock sequences. The effects of aftershocks on the damage and lateral displacement of underground structures were preliminarily revealed. The structural deformation response of each layer varies greatly due to the different damage states of the mainshock. The maximum story drift θ of the structure increases with the increase of loading seismic intensity. From the perspective of seismic damage and relative deformation, the structural dynamic response, considering the effect of sequential earthquakes, is greater than that of the mainshock alone, which reflects the disadvantage of aftershocks in seismic design. The results provide a reference for seismic analysis and damage assessment of structures under sequential earthquakes. • Nine mainshock-aftershock sequences were constructed based on the basic concept of endurance time analysis. • The seismic responses of subway stations subjected to mainshock-aftershock sequences were discussed and analyzed. • The amplitude variation surface and contour line of θ max under different seismic intensities were proposed. [ABSTRACT FROM AUTHOR]

Accurate post-earthquake damage evaluation of real-world structures is essential to ensure the safe operation of buildings. To this end, we propose a damage evaluation method for earthquake-excited structures relying on the hysteresis curve reconstruction approach. Central to this method is the use of an equivalent single-degree of freedom (ESDOF) system, designed to model structural overall hysteresis and to facilitate an acceleration-based Damage Indicator (DI). Differently from the previously investigated hybrid damage index, a data-driven variant of this DI, configured for reduced reliance on model information and enhanced computational efficiency, is here introduced. This DI is integrated into a framework for assessing structural damage and seismic performance levels, leveraging Seismic Structural Health Monitoring data. The reliability and robustness of the DI with respect to earthquake excitation of different characteristics and for a varying number of floors is assessed by adopting a simulated five-degree-of-freedom degradation model. A large-scale RC frame shaking table test is employed for a comprehensive evaluation of the proposed scheme, allowing to illustration of the damage assessment and the damage state evaluation performance of the proposed data-driven DI. Though the utilization of the ESDOF concept precludes the evaluation of the intensity and location of structural damage, the damage state evaluation results may still provide effective physical information besides the DI values. The relatively low requirements for prior model information and nonlinear behavior render the proposed DI applicable to real-world implementation. This promising characteristic may consequently facilitate the rapid post-earthquake decision-making process. • A framework for structural damage quantification and damage state evaluation leveraging SHM data is proposed. • A large-scale RC frame shaking table test is employed to illustrate the damage evaluation performance for the proposed DI. • The relationship between DI value and damage state is established to determine thresholds for rapid post-earthquake decisions. [ABSTRACT FROM AUTHOR]

Seismic intensity measures are one of the core parameters for estimating regional bridges' seismic risk and vulnerability. Using macroscopic seismic intensity indicators to predict and assess the seismic vulnerability of bridges can contribute positively to establishing urban and rural earthquake risk models. However, the developed vulnerability model rarely considers the contribution of instrument intensity to its quantification results and ignores the influence of nondamage bridge samples on the development of bridge risk models and the membership relationship between seismic vulnerability levels, which makes the developed model somewhat localized and uncertain. This study proposes a quantitative method and innovative model considering composite seismic intensity (instrumental and macroseismic intensity) indicators. The model was updated and validated using 300,000 acceleration records monitored by ten seismic stations during the Luding earthquake on September 5, 2022, in China, and the features of seismic motion parameters were analysed. The established empirical vulnerability dataset of bridges during the 2008 Wenchuan earthquake in China was updated and optimized using the developed models and methods. The traditional vulnerability level of bridges has been expanded by adding and refining actual samples (2317 bridges) from different seismic intensity zones. A vulnerability prediction model based on an updated extended bridge database was developed using nonlinear regression methods. A fragility membership index calculation model for estimating the correlation features of bridge vulnerability levels is proposed by combining the probability risk and fuzzy membership correlation algorithm. The traditional method for calculating the seismic vulnerability index has been improved, and a multiparameter bridge vulnerability model validation and rationality analysis have been conducted using the newly developed bridge sample dataset. ● A fragility membership index is proposed to estimate the seismic risk of bridges. ● A mixed intensity model for estimating seismic risk of bridges has been proposed. ● The traditional nonlinear fitting model and fragility index have been updated. [ABSTRACT FROM AUTHOR]

Telecommunication system is one of the critical lifeline systems for national life and post-earthquake emergency response. Telecommunication equipment is the necessary components to preserve communication functionality of telecommunication system. The severe damage and functionality loss of data center buildings resulting from damage to telecommunication equipment are frequently reported following earthquakes. Thus, there is an increasing need to understand the performance of telecommunication equipment during earthquakes. Seismic investigation of three server cabinets in internet data center buildings are presented in this study. The seismic damage and dynamic characteristics of server cabinets were evaluated and explained in terms of the natural frequency, stress, acceleration, dynamic amplification factor, and deformation by triaxial shaking table tests. The input acceleration time histories were generated based on the required response spectra in YD 5083 code and AC 156 code, with seismic intensities ranging from 0.1 g to 1.2 g. Based on the test results, the effects of different mass distributions inside the cabinets and earthquake inputs were investigated. The seismic damage limit states of server cabinets were identified based on observed damage phenomenon. The corresponding seismic fragility models of server cabinets were developed based on shaking table test data. The results show that the Power Distribution Units inside the cabinets still worked normally and the output voltage was normal for all loading cases although the frame of cabinets suffered severe seismic damage. The normal functionality of server cabinets including more electronic devices and equipment should be carefully checked by shaking table tests. • Shaking table tests were conducted on three server cabinets. • The seismic response of server cabinets was investigated. • The seismic damage limit states of server cabinets were identified. • Seismic fragility curves of server cabinets were developed. • The efficiency of different IMs in predicting the damage states was estimated. [ABSTRACT FROM AUTHOR]

Urban highway bridges are crucial for regional economic development and population mobility, but they are vulnerable to seismic hazards. Accurately predicting the seismic demands of bridges is essential. Several commonly-used methods for seismic demand estimates, such as cloud analysis, incremental dynamic analysis, and multiple stripe analysis, are computationally expensive and subject to theoretical assumptions and convergence issues, especially for portfolios of bridges. Machine learning techniques can be effective, but their lack of interpretability hinders understanding of the surrogate model's predictions. To address these challenges, this study develops a Bayesian-optimized interpretable ensemble learning surrogate model for predicting and interpreting the critical seismic demands of urban highway bridges.Thousands of continuous prestressed concrete girder bridges with typical geometric configurations in China are generated, and 120 ground motion records with different frequency, waveform, and duration characteristics are chosen. The seismic demand dataset is established based on nonlinear time-history analyses for urban highway bridges, accounting for different types of uncertainties. The surrogate models are developed based on the XGBoost ensemble learning method, with hyperparameters automatically and efficiently determined by Bayesian optimization technique. Compared to the random search and grid search methods, Bayesian optimization is approximately 8 times and 29 times faster, respectively, and it also achieves the highest prediction accuracy. Meanwhile, the relationship of each hyperparameter in the surrogate model is also revealed. The prediction results of the proposed model are compared with other machine learning models. The SHAP algorithm is subsequently used to explain the model predictions regarding the feature importance, global interpretations, and feature dependency analysis. The study quantifies the contribution of each structural feature and seismic intensity measure to the selected critical seismic demand and identifies the interaction effects between different input variables in the prediction. • An interpretable surrogate model for seismic demand predictions of bridges is developed. • Bayesian-optimized model tuning is developed to determine the optimal hyperparameters. • Key structure and quake characteristics for demand predictions are quantified and interpretated. • Interaction effects between different input characteristics on demand predictions are revealed. [ABSTRACT FROM AUTHOR]

A deep learning-based rapid peak seismic response prediction model for the most common two-story and three-span subway stations is proposed in this study. The established model predicts the peak seismic responses of subway stations with a data-driven fashion and using limited information. The prediction model extracts the features of ground motions using one-dimensional convolutional neural network (1D-CNN) and then integrates the information of subway stations (i.e., the seismic fortification intensity, buried depth, and shear wave velocity) through a fully connected neural network for regression, resulting in peak seismic responses, namely the peak floor acceleration (PFA) and maximum inter-story drift ratio (MIDR). The model is trained using 19,200 samples obtained from the nonlinear time-history analyses (NLTHAs) of the designed 48 typical subway station structures. Furthermore, the external model verification was performed on 960 additional samples. For the predictions of PFA and MIDR , the coefficient of determination (R 2) values are 0.967 and 0.986, respectively, and the damage states of subway stations are further evaluated, achieving an accuracy of 95.0%. These indicates that the model has good predictive performance and generalization ability. Moreover, the prediction model demonstrates a significantly higher computational efficiency compared to numerical simulation methods. ● Deep learning-based peak seismic response prediction model for two-story and three-span subway stations is established. ● Ground motion and structural characteristics can be considered simultaneously. ● The developed prediction model just requires the limited structural information. ● Peak seismic responses of each layer in subway stations can be obtained by the model. [ABSTRACT FROM AUTHOR]

This research aims to estimate the expected economic losses associated with the repair cost of a set of code-compliant moment-resisting reinforced concrete buildings located on different soil conditions in Mexico City. The loss assessment methodology is based on the second generation of the Performance-Based Earthquake Engineering (PBEE) framework, which quantifies the seismic performance of buildings in terms of metrics such as economic losses, downtime, and casualties, which are more meaningful to owners and stakeholders for the decision-making process. The methodology uses a probabilistic approach that takes into account uncertainties in seismic intensity, structural response, component damage, and consequence prediction. The seismic response of structures was calculated in terms of inter-story drifts and floor accelerations to assess the damage to their structural and non-structural components. In addition, taking into account the seismic hazard of the site, the expected annual losses (EAL) are calculated to provide insight into the seismic performance evaluation of structures with different characteristics in terms of the financial impact in seismic-prone regions like Mexico City. • Evaluation of seismic performance of buildings in terms of economic losses using FEMA P-58 guidelines facilitates the decision-making process. • Buildings located on soft soil in Mexico City exhibit considerably higher expected annual losses (EAL) compared to those located on firm soil zones. • Code-compliant RC MRF buildings located on firm soil zone of Mexico City are repairable for seismic intensities lower or up to the design intensity. • Economic losses in RC buildings designed according to the Mexico City Building Code are mostly influenced by small or moderate seismic intensities. • The analysis of expected economic losses permits identifying actions to enhance seismic resilience in high-risk regions like Mexico City. [ABSTRACT FROM AUTHOR]

• Suitabilities of intensity measures are quantified using the information theory. • Multi-linear demand models are developed for pulse-like and ordinary records. • Applications of vector measures are not recommended in low and moderate damage levels. • A simple intensity measure is recommended in a single-demand model. The estimation of seismic demand that connects the ground motion intensity measure and the damage measure of structures is one of the most important components in the performance-based design. The random nature of earthquake ground motion with great uncertainties in structural properties has posed challenges before this estimation. In this study, the suitability of different scalar and vector intensity measures of ground motion is quantified by using information theory and relative entropy concepts in the representation of ground motion uncertainty. The multilinear demand models for a better estimation of the seismic demand of structures are developed for near-fault pulse-like and ordinary ground motions, separately. The results indicate that the measures based on the spectral acceleration, velocity, and vector values are more appropriate intensity measures in the low, moderate, and high levels of damage for pulse-like records, respectively. For ordinary records, the use of vector IMs is not recommended due to their complexities and slight superiorities to scalar IMs. If the evaluations require a simple IM in a single-linear demand model for all the damage, the measures of VSI and SI H would be recommended. [ABSTRACT FROM AUTHOR]

• Quantifying the fracture-leading ductility through tested square HSS braces. • Developing ductility-based fragility curves to estimate fracture of HSS braces. • Seismic risk assessment of braced frames in existing buildings. • Fracture probability of fracture of HSS braces is high at expected demand levels. A study on the seismic ductility demands on square HSS braces in special concentrically braced frames (SCBFs) is presented to address the seismic risk of braces in existing SCBF buildings designed according to both previous and current AISC Seismic Provisions. First, the paper discusses the development of ductility-based fragility curves by employing specimens with various width-to-thickness and slenderness ratios collected from 16 experimental programs from 1978 to today. Second, the constructed fragility curves are used to estimate the vulnerability of square HSS braces to the damage state of fracture using the brace ductility demand as engineering demand parameter. Then, the seismic risk of braces in terms of fatigue life is evaluated under 30 earthquake ground motions using a seven-story office building designed following requirements of previous and current design practice. The study concludes that braces in SCBF designed in compliance with the previous and current AISC Seismic Provisions are subject to a high probability of fracture under earthquake ground motions characterized by different intensity levels, which in turn might lead to underestimation of the overall seismic risk. [ABSTRACT FROM AUTHOR]

• There is an increasing demand for conducting nonlinear dynamic analysis to account for permanent deformations. • The adaptive controller deals quite well with the nonlinear behavior. • MR damper is promising control device. • Connecting adjacent buildings with MR dampers is an effective strategy. The efficacy of using the simple adaptive control method for alleviating the seismic responses of two nonlinear adjacent buildings connected at multiple levels with magneto-rheological dampers is investigated. The connected system is formed by two shear-type model buildings of the same height but have different dynamic characteristics so that the fundamental frequencies of the individual buildings do not coincide. A stable hysteretic behavior of the structural system is considered in the current study, which captures the variation in flexibility and energy loss under various intensity levels of seismic events. The Bouc-Wen's nonlinear differential equation is utilized to model the hysteretic behavior of the restoring force-displacement smooth curve of the developed nonlinear structural system which is then integrated into a semi-active adaptive control system. The advantage of using the Bouc-Wen model is that it has the ability to mathematically track various shapes of the force-displacement curves by adjusting its non-dimensional parameters. The proposed nonlinear model is validated through a finite element model. Adaptive control is well suited to handle the nonlinear behavior because the adaptive control gains can be adjusted depending on the situation through a closed-loop action to yield better performance. The results show that using the adaptive controller to drive the magneto-rheological dampers connecting two adjacent nonlinear buildings can be used to effectively alleviate the seismic responses and reduce permanent deformations. However, the performance improvement is not the same under all ground motions considered in this study. [ABSTRACT FROM AUTHOR]

• A demand index quantifying the residual deformation ratio is defined. • Near-fault ground motions are applied as input excitations. • Effects of the damage-control core and its shifting path are studied. • Empirical formulas of residual displacement ratio demand are developed. This research investigates the post-earthquake residual displacement ratio demand of high strength steel frames with energy dissipation bays (HSSF-EDBs) under near-fault earthquake ground motions. The study focuses on the ultimate stage of the structure where the HSS frame develops sufficient inelastic deformations. The nonlinear force-displacement behaviour of a HSSF-EDB is idealised by a classical trilinear kinematic model, and the idealised hysteretic behaviour is assigned to oscillators for representing the novel system. To facilitate performance-based seismic design of HSSF-EDBs, the post-earthquake residual displacement demand is related to the yield displacement characterising yielding of energy dissipation bays using the trilinear oscillator analogy, and a non-dimensional residual displacement ratio is proposed. A large number of inelastic spectral analyses of trilinear oscillators covering a reasonable spectrum of hysteretic parameters are performed to quantify the influence of the essential variables on the residual displacement ratio demand of the systems. The results show that the residual displacement ratio of trilinear oscillators representing HSSF-EDBs subjected to near-fault earthquake ground motions is affected by hysteretic parameters in various yielding stages. To offer a practical tool for estimating the residual displacement demand of HSSF-EDBs in the preliminary design phase, empirical formulas quantifying the post-earthquake residual displacement ratio demand of trilinear oscillators are proposed. Finally, the effectiveness of using trilinear oscillators for quantifying post-earthquake residual displacement demand of HSSF-EDBs is emphasised by a comparative study on seismic responses of a prototype HSSF-EDB system and equivalent oscillators under near-fault ground motion samples. [ABSTRACT FROM AUTHOR]

Highlights • Ground-motion duration and spectral shape affect the seismic performance of SCBFs. • Most inside-basin ground motions caused damage states at lower spectral acceleration. • A combined intensity measure reduces uncertainty in the damage fragility functions. • Basin effects should be considered in structural design. Abstract Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is not explicitly considered in the seismic design values used in the U.S. building codes. In the Pacific Northwest, the basin amplification of ground motions from subduction zone interface earthquakes is particularly important, because such earthquakes contribute significantly to the seismic hazard at natural periods for which basin amplification is high. Additionally, interface earthquakes have long durations, the effects of which are also not considered in building codes. Research into seismicity of these regions has been plentiful but few studies have evaluated the impact on the built environment. Using advanced nonlinear modeling approaches, a commonly used system, special concentrically braced frames, was studied with an eye towards comparing the performance of crustal and subduction-zone earthquakes. Using standard performance and collapse-assessment procedures, 3-, 9-, and 20-story SCBF archetypes were subjected to large-magnitude interface earthquakes recorded in basins in Japan; these motions were selected because they were recorded in locations with similar depths as the Seattle basin. The results demonstrate that deep basins in combination with the long ground-motion duration results in brace fracture at lower spectral accelerations, S a. Similarly, collapse is associated with lower values of S a. The results suggest that the strength of the archetypes inside deep basins and subjected to interface earthquakes would need to be increased by a factor of over 2.0 to ensure similar collapse probabilities as those located outside basins and/or subjected to crustal earthquake hazards. The results are similar to those obtained for other seismic resisting systems previously studied. [ABSTRACT FROM AUTHOR]

Highlights • Traditional and new rehabilitation strategies of historic buildings are presented. • The base isolation method stands out as suitable, especially for heritage churches. • In this paper the base isolation process is extensively described and commented. Abstract The first part of the paper focuses on briefly presenting the background referring to the necessity of rehabilitating the heritage church buildings and to the general principles and strategies that dominate the rehabilitation processes and techniques. Also, some of the most important buildings that underwent through a base isolation process are exemplified, from ancient to present times, both world wide and in Romania. The second part of the paper presents a case study referring to the first historic heritage church building that was base isolated in Romania, St. Nicolae Aroneanu Orthodox Church, located in Iasi County. Being erected in 1594, the church follows the traditional orthodox architectural patterns of those times, from both esthetical and structural points of view. The rehabilitation necessity was imperative, since the church was severely damaged by numerous strong seismic actions during the last 400 years. After extensive and wide-ranging investigations and evaluations, the base isolation method was selected as the appropriate rehabilitation solution. The system consists in installing 48 friction pendulum sliding (FPS) isolators, between two horizontal reinforced concrete carrying elements that were casted at the infrastructure level, followed by decoupling the superstructure of the church from the existing foundation system and transferring it to the seismic isolators. Since it has never been previously applied to Romanian heritage church buildings, the execution process was divided into several technological stages, each of them being extensively discussed, by highlighting the advantages and drawbacks that arose. The main advantages that derived from applying the base isolation rehabilitation strategy refer to a considerably improved response of the structure to the high intensity seismic actions that are specific to the north-eastern part of Romania and to a significant reduction of the drift displacements and of the shear forces in the structural masonry walls. Nevertheless, by far the most important advantage consists in the fact that all necessary rehabilitation works are performed at the infrastructure level, without generating risks of damaging the heritage architectural and artistic components of the church. [ABSTRACT FROM AUTHOR]

• Large-scale testing of RC piers reinforced with high strength materials. • Seismic behavior and repairability of RC piers are discussed. • Develop a valid FEM method to model the nonlinear behavior of RC piers. • Perform seismic fragility analysis to evaluate the effects of high strength materials on the seismic performance of RC piers. The use of high-strength steel bars (HSSB), high-strength concrete (HSC) and ultra-high performance concrete (UHPC) in bridge piers can obviously improve bearing capacity and save material consumption. However, the use of high strength materials may detrimentally affect the seismic performance of reinforced concrete (RC) piers. This paper tries to study the seismic performance of RC piers with HSSB and HSC/UHPC by quasi-static tests and seismic fragility analysis. Three RC piers, solid pier with normal strength steel bars (NSB) and normal strength concrete (NSC), solid pier with HSSB and HSC, and hollow pier with HSSB and UHPC, were designed and tested under quasi-static loading. The failure mode, hysteretic performance, stiffness degradation and residual displacement of three specimens were compared and analyzed. A fiber-based beam-column finite element model (FEM) was developed to simulate the nonlinear response of RC piers with HSSB and HSC/UHPC. On this basis, the seismic fragility analysis was performed to study the effects of high-strength materials on the seismic performance of RC piers. Research results show that, compared with NSC piers, HSC piers reinforced with a small amount of HSSB still exhibited slightly larger lateral bearing capacity but lower deformability due to the higher brittleness of HSC. The UHPC hollow pier presented obviously larger deformation capacity, and more slow decline speed of lateral stiffness than NSC and HSC solid piers. Meanwhile, the matching use of UHPC and HSSB in hollow pier can improve the elastic deformation, and then reduce residual displacement of RC piers. The proposed fiber-based finite element model (FEM) can simulate the nonlinear response of RC piers with different high-strength materials with reasonable accuracy. Fragility results demonstrate that, HSC pier presents lower seismic fragility than NSC pier at different damage states except for collapse due to lower ductility of HSC pier. The UHPC hollow pier with HSSB has lower seismic fragility than NSC and HSC solid piers at the same seismic intensity. Overall, the hollow pier with HSSB and UHPC can maintain good seismic performance while greatly saving material consumption. [ABSTRACT FROM AUTHOR]

• A novel high-performance structural system for tall building application in high seismic zones. • Detailed equivalent energy design procedure for the newly proposed system has been presented. • The seismic performance of the proposed structural system is demonstrated using the detailed nonlinear time history analysis. In this paper, a novel earthquake resilient reinforced concrete core wall system named the controlled rocking outrigger core wall (CROCW) system is proposed. The CROCW consists of two high-performance seismic force resisting systems along its two principal axes. Along one principal axis is the controlled outriggered rocking wall (CORW), where an outrigger is situated at the roof and controlled rocking at the base. Dampers are incorporated within the outrigger and the rocking base to allow CORW to provide stable energy dissipation during earthquake excitation. Along the other principal axis is the self-centering coupled wall (SCCW). In the SCCW system, the self-centering friction dampers are incorporated within the coupling beams to dissipate the earthquake energy, while the base is designed to rock. The proposed CROCW system can be designed using the novel equivalent energy design procedure (EEDP). Four prototype buildings (two different building heights and two different building sites) were designed using the EEDP presented in this paper. The detailed nonlinear time history analysis was conducted to assess the performance of CROCW system. The results demonstrate that the CROCW system can be efficiently designed using the EEDP procedure to achieve a superior performance and low damage response at multiple levels of earthquake shaking intensities. [ABSTRACT FROM AUTHOR]

• Analyse the seismic responses of super high-rise buildings under long-period ground motions. • Present comparative study between the effects of long-period ground motions and ordinary earthquake excitations on super high-rise buildings. • Examine the effectiveness of earthquake intensity measures on reflecting the influence of long-period ground motions on super high-rise buildings. • Provide valuable information for seismic analysis and design of super high-rise buildings. Super high-rise buildings usually exhibit low fundamental frequencies and are particularly susceptible to Long Period Ground Motions (LPGMs) characterized by rich components in long-period range. Previous seismic analyses of super high-rise buildings have primarily considered ordinary earthquake actions, overlooking the influence of LPGMs. To address this gap, the seismic responses of super high-rise buildings ranging in height from 400 m to 800 m are investigated when subjected to LPGMs. The effectiveness of earthquake intensity measures, which serve as indices connecting seismic hazards to structural responses, is evaluated in capturing the seismic effects caused by LPGM excitations. Firstly, this study introduces a statistical model for the response spectra of LPGMs. A simulation algorithm utilizing Continuous Wavelet Transformation (CWT) is then employed to generate LPGMs. Subsequently, simplified shear-flexural models are applied to serve as computational models for super high-rise buildings with varying heights. Furthermore, this study calculates, analyzes and compares typical seismic responses, such as lateral displacements and inter-story drifts, of these super high-rise buildings under simulated LPGMs and ordinary earthquake excitations. Additionally, a set of seismological ground motions is utilized to validate the seismic response analysis. The findings of this study reveal that LPGMs lead to significantly larger responses of super high-rise buildings exceeding 400 m in height compared to ordinary earthquakes. Furthermore, this study examines the correlation coefficients between various existing earthquake intensity measures and seismic responses under LPGM excitations. The results indicate a strong relationship between the LPGM induced responses and the spectral acceleration and velocity at the fundamental periods of the structures. The aim of this paper is to explore the seismic response of super high-rise buildings under LPGMs and provide a scientific basis for their seismic analysis and design. [ABSTRACT FROM AUTHOR]

• Framework is established for performance-based assessment in post-earthquake fire engineering. • Methodology is illustrated by a case study on the performance evaluation of a steel system. • Dual-cause PEF ignition model is built for the probabilistic causation in earthquake-fire sequence. • Structural demands to both intensities are obtained by nonlinear analyses and mathematical extension. • Damage and loss assessment is conducted with fragility development and indicator quantification. Post-earthquake fire (PEF) is a threatening hazard triggered immediately after an earthquake, resulting in extensive destruction and casualties. It is important to evaluate structural performance in this typical cascading hazard to develop mitigation strategies and improve multi-hazard resilience. However, existing research mainly focuses on the structural response in PEF scenarios, while there is still a lack of knowledge on other critical parts of performance evaluation. In contrast, there has been a well-established methodology for performance-based assessment in earthquake engineering (PBEE), which can be regarded as the basis for extension to PEF scenarios. Based on that, a comprehensive framework has been proposed in this study for performance-based assessment in post-earthquake fire engineering (PB-PEF-E). To demonstrate the feasibility of the proposed methodology, an illustrative example of a realistic multi-storey steel frame is presented with specific details. The overall procedure considering the hazard, structure, damage, and loss domains is utilised for step-by-step PEF performance evaluation. Firstly, a dual-cause PEF ignition model is used to capture the probabilistic causation among the earthquake-fire sequence, considering ignition related to utility system damage and ignitable contents overturning. Then, structural demands with respect to both earthquake and fire intensities are obtained by a series of nonlinear analyses via numerical modelling, and uncertainties that significantly influence the responses are included. Finally, the structural capacity in different performance levels is estimated with PEF fragility development, and the consequences are measured using quantitative indicators for decision-making. The proposed methodology provides important benefits in evaluating the performance of alternative solutions thus facilitating robust decision-making in PEF scenarios, and it can be further extended to performance-based assessment in other multi-hazard scenarios with cascading effects. [ABSTRACT FROM AUTHOR]

• An integrated ground motion clustering and probabilistic ML framework is proposed for structural fragility analysis. • To demonstrate the proposed framework, a 3-span, 6-storey reinforced concrete frame system is studied. • The ground motion clustering base on time series K-means algorithm effectively reduces the prediction variability. • The probabilistic ML method is capable of simplifying the acquisition process of seismic fragility curves. Machine learning (ML) techniques have been recently adopted in engineering practice to define the relationship between seismic intensity measure (IM) and structural damage measure (DM) based on a limited set of numerical simulations. However, they only offer deterministic prediction, which failing to reflect the aleatoric uncertainty related to input variables (e.g. seismic excitation and structural properties) and the epistemic uncertainty associated with modeling. This paper proposes a probabilistic ML method combined with ground motion clustering for seismic fragility analysis of structures. In the probabilistic ML method, by the natural gradient boosting (NGBoost), the conditional probability distribution can be evaluated for each structural response instead of producing point estimation. In addition, ground motion clustering is based on the time series K-means, which can capture the hidden features and select the representative subset of ground motions. The proposed framework was implemented for seismic fragility analysis of a typical 3-span, 6-storey reinforced concrete (RC) frame system. Analysis results indicated that the point estimation accuracy of the NGBoost was comparable to that based on excellent deterministic ML techniques, e.g. artificial neural network (ANN), random forest (RF), extreme gradient boosting (XGBoost). Moreover, the probabilistic prediction can efficiently provide the conditional probability of exceeding a damaged state in the structure given an IM level, eliminating the need for additional input of uncertainties from structural properties in traditional ML methods. Ultimately, the cluster-based ground motion selection reduced the model uncertainty and improves the prediction accuracy of the probabilistic ML model. [ABSTRACT FROM AUTHOR]

Highlights • DEM to investigate the in-plane seismic behaviour of rammed-earth walls. • A real earthquake excitation was applied to the model. • Excitation was scaled at different amplitudes to assess the damages. • For excitations lower than 2.3 m/s2, rammed-earth walls had satisfying performance. Abstract Rammed earth (RE) is a construction material which is manufactured by compacting the soil within a formwork, in superimposed layers. RE is attracting scientific studies because of its sustainable properties : a very low embodied energy and an advantageous living comfort due to a particular benefic hygro-thermal behaviour. Numerous studies have been conducted to investigate RE material and RE structures, however, a lack of knowledge on the seismic performance of RE buildings is noticed. This paper presents an advanced numerical study to investigate the in-plane seismic behaviour of RE walls. First, a numerical model of an in-situ RE wall was constructed by using discrete element modelling (DEM). The relevancy of the numerical model was verified by comparing dynamic properties of the model with that measured on the in-situ wall. Then, a real earthquake excitation was applied to the model, in order to evaluate the seismic performance of the RE wall studied. This is the first time, to our knowledge, that a dynamic discrete explicite analysis was performed for a RE wall. The excitation was scaled at different amplitudes to assess the damages following different earthquake intensities. The results showed that for seismic excitations lower than 2.3 m/s2, RE walls studied had satisfying in-plane earthquake performance. [ABSTRACT FROM AUTHOR]

Most current structural fire codes focus on achieving prescribed fire ratings, which are based on standard fire tests with minor relevance to what is required for fire safety. These prescriptive design approaches do not provide sufficient information regarding the performance of structural members or systems under elevated temperatures. Furthermore, the limited structural design provisions provide no indication of the level of reliability of structures since comprehensive treatment of the uncertainties associated with the hazard is not considered. It is therefore imperative to move towards performance-based engineering not only to quantify structural reliability for given performance objectives but also to ensure more economic and safe design. This paper provides details on the development of a new analysis framework for probabilistic performance-based analysis of a fire following an earthquake. The framework is then utilized to develop fragilities of steel structural members and systems subjected to cascading hazards of earthquake and fire while considering buckling of columns as the damage limit state. Uncertainties associated with fire hazard, passive fire protection, gravity load, and earthquake intensity are accounted for in the framework. The proposed performance-based approach for the analysis of a fire following an earthquake can be considered an extension of the Pacific Earthquake Engineering Research (PEER) performance-based earthquake engineering framework and used by engineers to assess structural performance under the multiple hazards. [ABSTRACT FROM AUTHOR]

Improving predictive relationships between strong ground motion and seismically induced damage in buildings is an important topic for seismic risk assessment. Spectral acceleration at a structure’s fundamental period S a ( T 1 ) has often been used as the indicator of the potential damage a given ground motion may induce on structural systems. However, such a scalar indicator (Damage Potential Indicator, DPI) captures only limited information about the ground motion time history and response spectrum shape. In a severely damaged state, the effective period of a structure will change, which makes the structure respond to other parts of the response spectrum. In this study, a new response spectrum-based DPI that contains an intensity component and a spectral shape component is proposed. The critical period range of the response spectrum that should be considered in spectral shape evaluation is determined using a circle rule for bilinear single-degree-of-freedom (SDOF) systems. The effectiveness of the newly proposed DPI is validated by comparing damage potential similarity using a database of ground motion records. [ABSTRACT FROM AUTHOR]

This paper deals with the need of extending results of deterministic rocking analyses to stochastic analyses on restrained masonry façades in one-sided motion. The purpose is to define the level of improvement achieved with any anti-seismic device of a given stiffness and strength, in terms of reduction of probability of exceedance of a certain limit state. The most efficient intensity measures (IMs) are identified for three masonry façades of churches in free and restrained conditions. A reliability analysis is carried out by considering over 70 earthquakes, of which 50 recorded during the recent 2016–2017 Central Italy Earthquake. Four limit states are taken into account: rocking initiation, limited rocking, moderate rocking and near-collapse condition. The yielding limit state is considered for the analysis with anti-seismic devices. Univariate and bivariate fragility curves (FCs) are compared in free and restrained configurations, to discuss the reduction of probability of exceedance depending on 15 intensity measures. The results show that the best IMs are velocity-based parameters, in particular the Fajfar Index and Peak Ground Velocity, together with Peak Ground Acceleration. In one-sided motion without restraints, the higher the compression stiffness of the sidewalls, the more unstable the wall is in probabilistic terms. Practical curves show, for each IM, the reduction of probability of exceedance obtained thanks to assumed horizontal restraints. These help to understand, in a stochastic perspective, to what extent the anti-seismic device can be beneficial or detrimental (in case of amplifications of motion) for given earthquake intensities. The comparison of univariate and bivariate FCs confirms the superiority of bivariate FCs. Indeed, often the univariate curves sensitively underestimate the probability of exceedance, especially for low-medium intensity earthquakes, and are not able to offer any information regarding the influence of other IMs. [ABSTRACT FROM AUTHOR]

• This paper proposes a method for calculating design seismic-induced irregularity for random high-speed railway structures under arbitrarily seismic intensity and structural damping ratio, providing a basis for the determination of post-earthquake driving speed. The determination of post-earthquake driving speed is one of the key issues for railway operation in seismic areas. Currently, research on design seismic irregularity is based on specific damping ratios, but the damping ratios of high-speed railway bridges are not constant. In this paper, the effects of damping ratios on seismic-induced irregularity and design seismic-induced irregularity were compared. The amplitude response spectrum of design seismic-induced irregularity considering the impact of damping ratios was established. The structural random adjustment coefficient of amplitude response spectrum was determined. The research results show that, when the characteristic period remained unchanged, the position of amplitude response spectrum rises with the increase of seismic intensity. When the seismic intensity remained unchanged, the position of amplitude response spectrum rises with the increase of characteristic period. High-speed trains should be appropriately decelerated when traveling from a hard site to a soft site with the same seismic intensity or traveling from a near field site to a far field site. With the increase in seismic intensity, the structural random adjustment coefficient drops obviously. As the characteristic period increases, the structural random adjustment coefficients show no noticeable change. [ABSTRACT FROM AUTHOR]

• UHPC were partially applied in the boundary elements of the shear walls. • The behavior of shear walls was tested under axial load and cyclic lateral load. • The influence of axial load ratio, UHPC distribution height and width was studied. • The failure modes and hysteretic behavior of shear walls were analyzed. Inspired by studies on shear walls reinforced with high performance cement-based materials, this paper explores the applicability of ultra-high performance concrete (UHPC) for improving the seismic behavior of shear walls. In this study, a novel shear wall partially strengthened with UHPC in the boundary element was developed, in which the UHPC was cast into the potential plastic hinge region of the boundary element. Partial application of UHPC can reduce construction costs and promote its use in building structures. To study the influence of distribution height and width of UHPC and axial load ratio on the seismic performance, six shear walls with a shear span ratio of 2.1 were tested under axial load and cyclic lateral load. The failure modes, lateral load-lateral displacement hysteretic behavior and ductility of the shear walls were also investigated. The experimental results indicated that the partial application of UHPC in boundary elements could effectively improve the performance of shear walls. Moreover, even if the volume ratio of UHPC was only 0.12, the shear wall partially strengthened with UHPC still showed good seismic performance under a high axial load ratio, indicating that this type of shear wall can be applied to the high seismic intensity and high axial load ratio regions. [ABSTRACT FROM AUTHOR]

• Four comprehensive three-dimensional bridge representations including as-built and retrofitted bridges (using SU-FREI) are developed. • • Damage potential of different bridge components are quantified under a vast range of subfreezing temperatures and seismic intensities. • • Cold temperature exposition does not necessarily have an adverse impact on the bridge performance. • • SU-FREI demonstrates an acceptable behavior even at extremely cold temperatures and long durations of exposure. • • Cold temperature provisions for SU-FREI developed by AASHTO are conservative. Several cold regions around the world are in seismic active zones. Seasonal freezing can significantly affect the seismic performance of complex bridge-isolator-foundation-soil systems by inducing brittle failure and premature collapse due to a combination of load reversals and cold temperature behavior of the bridge material. In cold conditions, constitutive material of bridge components, namely, concrete, steel reinforcement, rubber, and supporting soil undergo substantial stiffening which afflicts the ductility capacity of bridges. This study investigates the seismic performance of four bridge cases, namely, isolated bridge supported by pile groups, monolithic bridge supported by pile groups, isolated fixed-base bridge, and monolithic fixed-base bridge at room and subfreezing temperatures to unmask the effectiveness of using Fiber Reinforced Elastomeric Isolator (FREI) as a retrofit measure and to evaluate the performance of bridges at temperatures ranging from room (i.e. 20 °C) to −37 °C. To this end, an analysis matrix is developed based on the climatic condition of the bridge site along with the code provisions. A seismic fragility analysis is carried out in the context of Incremental Dynamic Analysis (IDA) using a set of synthetic ground motion records for longitudinal and transverse directions of the bridge, independently. It is shown that while the seismic isolation system can effectively mitigate the probability of damage to the bridge at room temperatures, isolated bridges demonstrated an acceptable behavior at subfreezing temperatures. [ABSTRACT FROM AUTHOR]

• A non-smooth model for earthquake-induced pounding in curved bridges is proposed; • The algorithm of linear complementarity form differential equations is programmed. • A numerical example is provided showing the capability of the proposed formulation. • The proposed method is examined in three ways: the linear complementarity relationship, the geometric relationship, and the impulse-momentum theorem. Curved beam bridges are widely used to accommodate the needs of complex transportation networks. However, these bridges are characterized by a complex dynamic response under earthquake excitation, and it is common to observe pounding-induced damages at the interfaces between adjacent beams or between the beam and the abutment after high-intensity earthquakes. The identification of pounding occurrences is a challenging task and highly dependent on the computational strategy used. The present paper addresses this problem by proposing and analyzing the suitability of an innovative non-smooth approach to solve the rigid bodies' dynamic response and contact interactions problem of curved beam bridges subjected to seismic ground motions. To this end, the dynamic equations of motions, including the pounding effects, are first formulated with the introduction of the Lagrange multipliers approach. The unilateral constraints are converted into a linear complementarity problem (LCP) formulation related to the velocity and impulse in the normal and transverse directions. The proposed algorithm of the differential equations in LCP form is successively implemented in Matlab to identify the collision and motion states by accessing the stepwise acceleration time history. A two-span curved beam bridge with an intermediate pier and two adjacent abutments under a single ground motion record is considered for case study purposes to investigate the suitability of the proposed procedure. The accuracy of the proposed method is verified by comparison with finite element (FE) analysis. The analysis results include the bridge's displacement time history and the motion states of all observed pounding occurrences. Finally, three validation methods, including the LCP relationship, the geometric relationship, and the momentum theorem, are evaluated to examine the validity of the proposed method. The results show that the proposed non-smooth dynamic formulation represents a new rigorous approach to identify and analyze the complex problem of end-pounding occurrence in curved bridges. [ABSTRACT FROM AUTHOR]

Bridges are common features of high-speed railway infrastructure. However, the performance of such bridges under seismic scenarios has not been well studied. To quantify possible damage levels of bridge components under different intensities of earthquake excitation, a 1/12-scale bridge specimen was constructed and tested using shaking tables. The experimental results of this investigation showed that not all bridge components were damaged when subjected to earthquake with the intensity of 0.20 g. A finite element (FE) model of the prototype bridge was also established and validated by the experimental results with consideration of similarity relationships. Finally, parametric studies involving different intensities of earthquake excitation were carried out by the validated modelling approach to study the damage levels of high-speed railway components under more severe earthquakes (i.e. 0.30 g, 0.40 g and 0.50 g). The results could be applied to quantify the levels of damage of the main components of high-speed railway bridges when subjected to earthquake intensities no greater than 0.50 g. Moreover, the numerical results showed that the shear reinforcement, fixed bearing and the pier installed with the fixed bearing were more vulnerable to earthquake excitation than the shear studs, slide layer, and cement asphalt mortar layer investigated in this study. [ABSTRACT FROM AUTHOR]

Many existing reinforced concrete moment frame buildings in high seismic regions around the world, including the U.S., were built without adequate seismic detailing. Quantifying the relationship between a set of quantitative parameters, known as collapse indicators, and collapse risk metrics can facilitate efficient identification, classification and retrofit of the most collapse-prone buildings. This paper investigates three collapse indicators: (1) the column-to-beam strength ratio, (2) the ratio of lateral (shear) strengths in adjacenot stories, and (3) the ratio of column flexural to shear strength. Each collapse indicator is varied separately through a parametric study of 36 idealized buildings, and nonlinear simulation models are dynamically analyzed for a suite of ground motions to assess the collapse performance. The results establish the relationship between the variation of the collapse performance of the building as a function of each collapse indicator, and identify the range over which variation of the collapse indicator significantly influences collapse performance, as well as upper and lower bounds beyond which the indicator is not significant. The results show that the deficiency associated with the column-to-beam strength ratio and the ratio of shear strengths in adjacent stories can be defined efficiently as the average of the associated values in the components at critical floor/story. For the collapse indicator related to the ratio to column flexural to shear strength, the collapse performance is strongly related to the average values in the critical story, and also the location of the most shear critical columns. The study also shows that the gradient of the collapse performance with respect to the three collapse indicators is similar. [ABSTRACT FROM AUTHOR]

The occurrence of earthquakes during the lifetime of bridges can result in the closure or even the failure of the structure. The vulnerability of multi-span continuous girder (MSCG) bridges strongly depends on the seismic performance of their columns. This paper investigates the seismic vulnerability of MSCG bridges with reinforced concrete (RC), steel fibre reinforced concrete (SFRC) and RC-SFRC columns. Quasi-static tests were conducted on eight different columns to obtain the limit-state capacities and validate numerical models. Numerical analyses were performed on MSCG reference bridges with RC, SFRC or RC-SFRC columns to derive probabilistic models for the demand on critical components. Fragility curves were established as a function of the peak ground acceleration by integrating the capacity distributions with the correlated component demand distributions. Results indicate that: (i) SFRC columns with 1.0% fibre ratio show a better performance-price ratio for improving the structural capacity compared with those with 1.5%; (ii) MSCG bridges with SFRC and RC-SFRC columns are less vulnerable to earthquakes when compared with those constructed using only RC, and the difference increases with the earthquake intensity; and (iii) the seismic vulnerability of MSCG bridges with SFRC placed only at the plastic hinges is similar to the one found with SFRC applied on the whole column. On a broader perspective, the conclusions drawn in this paper could offer a new strategy for the seismic enhancement or retrofit of MSCG bridges in earthquake regions, with optimal use of SFRC. [ABSTRACT FROM AUTHOR]

• The damage state and residual deformation of the bridge-track system after different earthquake intensities are studied. • OpenSees-TRBF co-simulation method is proposed for the running safety analysis considering the post-earthquake damage state of the bridge-track system. • The post-earthquake safety speed thresholds of train are analyzed. A bridge–track system (BTS) is inevitably damaged during an earthquake; this is reflected in its stiffness deterioration and residual deformation, which affect the post-earthquake running safety of trains. The influence of the post-earthquake damage state of an actual BTS on train running safety remains unclear. Hence, this study mainly discussed the influence of post-earthquake bridge–track damage state and residual deformation on running safety and established a safe speed limit for trains under different seismic intensities. A finite element (FE) model of a simply supported railway BTS was established using the OpenSees software. A nonlinear seismic response analysis was performed under different ground motion intensities (0.1, 0.3, and 0.6 g for frequent, design, and rare earthquakes, respectively), and bridge damage, fastener damage, and residual deformation of the rail after the earthquakes were studied. An OpenSees-TRBF (train-rail-bridge-foundation coupled system dynamic analysis software, TRBF) co-simulation method was developed to analyze the running safety of trains after earthquakes under a damaged state of the BTS based on the TCP/IP communication interaction technology. A safe speed limit for trains considering the post-earthquake damage state and residual deformation was proposed, providing a reference for the post-earthquake capacity of trains. The results of the BTS seismic damage analysis showed that the residual displacement of the bearing was the fundamental reason for the change in the rail line shape, and fastener damage mainly occurred in the range of 2–4 fasteners at the end of the girder under the design and rare earthquakes. The results of the running safety analysis showed that, if damage to the BTS is ignored, the running safety after an earthquake will be misjudged. Based on the continuous overrun time limit index, the running safety indices for ground motion intensities of 0–0.4, 0.4–0.5, and 0.5–0.6 g could meet the speed requirements of 350, 300, and 150 km/h, respectively. This study provides some references and suggestions for the running safety of trains following an earthquake. [ABSTRACT FROM AUTHOR]

• The life-cycle benefits of full self-centering structures (FSCSs) and partial self-centering structures (PSCSs) were comprehensively investigated. • Compared to the FSCS, the PSCS can achieve better performance in controlling PFAs, lowering base shear demands with comparable performance in controlling RIDs. • The PSCS can achieve better life-cycle benefits than the FSCS. • The life-cycle costs of FSCS and PSCS are highly influenced by the initial costs of self-centering braces. • It is critical to reduce the initial costs of self-centering structural members and control the floor acceleration responses for increasing the life-cycle benefits of self-centering structures. Various self-centering structural systems were developed and investigated for reducing residual inter-story drifts of the traditional aseismic structural system by achieving full or partial self-centering behaviors under earthquakes in the past twenty years. However, limited research was conducted to investigate the life-cycle benefits of the full and partial self-centering structural systems on the life-cycle span, figuring out a more cost-effective solution for enhancing the building's seismic resilience. This paper aims to comprehensively investigate the life-cycle benefits of full and partial self-centering structural systems compared to conventional buckling-restrained braced frames (BRBFs) using the life-cycle cost estimation method. The influences of the residual inter-story drift limit for demolition, the initial cost of emerging self-centering members, the value of building contents, and the discount rate were particularly investigated. To this end, three building structures with BRBFs and full and partial self-centering structural systems were designed to achieve the same capacity for controlling maximum inter-story drifts. Comprehensive dynamic analyses were performed to generate engineering parameters under different seismic intensities and the modeling uncertainties were properly considered through Monte Carlo simulation. The revised HAZUS loss calculation method was adopted to investigate the seismic annual loss (SAL) and life-cycle cost. The analysis results indicate that the partial self-centering behavior would be a better choice than the full self-centering behavior for developing the self-centering structural systems to achieve better life-cycle benefits. Moreover, it is essential and urgent to reduce the initial costs of self-centering structural members and control the floor acceleration responses for increasing the life-cycle benefits of self-centering structural systems and promoting their practical applications. [ABSTRACT FROM AUTHOR]

• Seismic fragility and risk assessment of self-centering (SC) wall structures with and without infill walls are studied. • Influences from traditional infill walls and infills with sliding joints on the performance of SC wall structures are compared. • The damage index of the integrated systems is considered to evaluate the seismic performance. • The new infill wall that combines the sliding mechanism and higher damping is more encouraged over the existing infills for developing an integral resilient system. Self-centering (SC) precast wall structures have emerged as earthquake-resilient structural systems with excellent seismic performances characterized by low damage as well as negligible post-earthquake residual deformation. However, research on SC wall systems often ignores infill walls for simplicity, which results in difficulty to achieve an integrated resilient structural system. To fill this gap, this paper presents a comprehensive assessment of SC precast concrete wall structures with three different types of infill walls and compares the results with that without infill walls. The maximum inter-story drift, the peak floor acceleration, and the damage index of the considered systems at different seismic intensities are calculated through incremental dynamic analysis. The assessment is then expanded from fragility to risk by evaluating the probabilities of exceeding each potential limit state throughout the service life. Results show that, despite merely no damage to the SC wall itself, the integral system could sustain significant damage due to the damage to the infills attached. What's more, with stronger infill walls, severer damage to the integral system is likely to be. Among the three infills considered in this study, the one with sliding joints performs the best from the perspective of damage, resulting in a smaller likelihood of 21%∼60% exceeding various damage limits than that of traditional infills. However, the sliding joint infill's benefit in damage is at the expense of larger drift and slightly higher acceleration responses compared with traditional infills. It is concluded that the infills considered in this paper all have their drawbacks and new infills that combine the sliding mechanism (to reduce damage) and higher damping (to reduce drift and acceleration) are encouraged to develop an integrated resilient system. [ABSTRACT FROM AUTHOR]

Aboveground-underground coupled structures (AUCSs) integrate aboveground multitowers, podiums, and large underground structures. The complex structural composition and connection forms enhance structure-structure and soil-structure interactions and result in a complicated structural seismic damage condition. The different dynamic characteristics of aboveground and underground structures make it difficult to select optimal seismic intensity measures (IM s) for the seismic damage evaluation of the AUCS. A refined nonlinear finite element model of the AUCS considering soil-structure interactions is established in this paper. Near-fault pulse-type and far-field ground motions are selected as seismic inputs. The structural seismic failure and its influencing factors, including ground motion characteristics and structural coupling interactions, are thoroughly examined. Numerical results demonstrated that structural seismic damage and weak positions are associated with the embedded effects induced by the podium and the underground structure. The structural failure begins at the column of the podium, and the failure modes are associated with the ground motion characteristics. The coupling interactions between towers are beneficial for reducing the seismic response of the AUCS. The wave scattering caused by the underground structure amplifies the seismic response of the aboveground structure as seismic intensity increases. A stability criterion for optimal IM selection is proposed, which evaluates changes in seismic response dispersion after the structure enters the plastic stage and can reflect the influence of dynamic characteristics of the AUCS on IM selection. Statistical results showed that the peak ground velocity and the root mean square velocity are optimal IM s for the evaluation of seismic damage of the AUCS. • The distinctive seismic damage and failure progress of the AUCS are investigated. • The failure modes of the AUCS are sensitive to ground motion characteristics. • The structural coupling interaction affects seismic responses of the AUCS. • A stability criterion for selecting optimal intensity measures is proposed. [ABSTRACT FROM AUTHOR]

• A novel dual-pinned self-centering coupled CLT shear wall (DSCW) is introduced. • An equivalent energy design procedure (EEDP) is proposed for the DSCW. • The EEDP is used to design the DSCWs of a 12-story prototype building. • A detailed finite element model of the DSCW is developed. • The seismic performance of the DSCW is assessed using NTHA and IDA. The use of mass timber structures has considerably grown in recent years. This has increased the demand for sustainable, resilient and high-performance mass timber structural systems. In this paper, a novel self-centering balloon-type cross-laminated timber (CLT) shear wall system, called the dual-pinned self-centering coupled CLT shear wall (DSCW), is proposed for tall building applications. The DSCW consists of two sets of CLT panels that are coupled to one another using self-centering friction dampers and are either pinned at their base or sit on V-shaped truss assemblies. This paper also introduces an equivalent energy design procedure (EEDP) that can be used to design the DSCW such that it meets different performance objectives and roof displacement targets at various earthquake intensities. The procedure was used to design the DSCWs of a 12-story prototype building located in Vancouver (Canada). The DSCWs of the prototype building were numerically modeled and subjected to extensive nonlinear time history and incremental dynamic analyses. The results of these analyses show that the proposed EEDP can be efficiently used to design the DSCW such that it achieves the target roof displacements and performance objectives. The results also show that the DSCWs of the prototype building meet the seismic performance requirements of FEMA P695. Overall, the results presented in this paper demonstrate that EEDP-designed DSCWs have excellent seismic performance and can be safely used in tall buildings located in high-seismicity regions. [ABSTRACT FROM AUTHOR]

• The cumulative distribution of displacement error E (change rate of peak displacement after considering VGM) was investigated and fitted with Gaussian function. • The mean of Gaussian function for friction bearings does not vary apparently, but the standard deviation changes significantly considering vertical ground motions (VGM). • The θ quantile of the Gaussian function is selected as the increment coefficient E θ considering VGM. • A mathematical model of E θ conditioned on the intensity of both horizontal and vertical ground motion is established. Friction isolation bearings are widely used in engineering structures, which exhibit good seismic isolation effects. Peak displacement of friction isolation bearing is crucial to measure the damage degree of frictional isolated bridge, and excessive displacement of the bearing may lead to serious earthquake damage such as beam-falling. However, the studies conducted for the impact of vertical ground motion on the peak displacement of friction isolation bearings were usually deterministic research, and the probabilistic research is insufficient. Therefore, the statistical method is used to explore the probabilistic distribution of the displacement error which is caused by neglecting the vertical ground motions. The error follows Gaussian distribution, and the relationship between the Gaussian function and the intensity of horizontal and vertical ground motions are quantitatively investigated. The results show that the mean value of the error is approximately equal to zero while the standard deviation is increased significantly with the intensity of the ground motions, which indicates that the vertical ground motion has little impact on the mean of the seismic demand, but strongly influences the dispersion. Finally, to facilitate the seismic design, different quantiles of Gaussian function are defined as the increment coefficient. A set of empirical formulas to predict the value of the increment coefficient are proposed, which provide a convenient method for designers and ensure the safety of bridge structures. [ABSTRACT FROM AUTHOR]