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The Andes, located along South America's western side, is among the world's longest mountain ranges and is one of the most intense seismic activity areas caused by the Pacific Oceanic plate sliding under the South American continent, mainly when the range passes through Peru and Chile, covering an area of 3.37 million km2. The Himalayas mountain range is among the most seismically active regions in the world, mainly when the range passes through Nepal, China, India and Pakistan, due to the collision between the Indian and the Eurasian continental plates, covering an area of 1.09 million km2. Eastern Anatolia mountain range of Turkey covering an area of 0.15 million km2 is also one of the most seismically and tectonically active regions due to the frequent occurrence of earthquakes. These three areas and other few in the vicinity of high seismicity were considered for this paper based on in situ working experience for several dam spillways and large dams with heights up to 335 m. Of these 50% under operation, 25% under construction and 25% under final design stages. The earthquake safety of dams is an important topic in dam engineering and dam safety, and the seismic behavior of dams subjected to severe earthquakes and mainly their consequences downstream must be very well defined providing the adequate seismic factors not only from the engineering point of view but also thinking on damage risks, for a proper application. This paper evaluates the main concept of seismic hazard analysis and the PGA value defined for these dams in the Andean, Himalayas and Eastern Anatolia mountain ranges for the MDE, SEE and OBE earthquakes and their implications for the dynamic and static analysis. [ABSTRACT FROM AUTHOR]

The pipeline, as the fifth largest transportation tool after railway, highway, waterway, and air transportation, has been widely used in industrial production and life. However, in the process of pipeline operations, rapid opening and closing of valves or pump stopping can lead to water hammer. The periodic pressure wave caused by water hammer can be much greater than the normal operating pressure of the pipeline. Because of water hammer, pipelines are susceptible to aging and damage that may cause local wall thickness reduction or local pipe property change. In this paper, singularity is defined as an abnormal state area during the use of the pipeline. It includes the corrosion thinning area of the pipeline wall, changes in the supporting environment around the pipeline, and the uneven stress area applied to the pipe wall because of water hammer vibrations. Different types of singular points have different characteristics. We focus on two types of singular points' characteristics in this paper: (1) nonpenetrating damage on the outer surface of pipe; and (2) local material change. Specifically, if the pipe wall thickness decreases locally due to pipeline damage, the ratio of wall thickness reduction to wall thickness corresponds to the depth of singularity, and the decrease of local wall thickness corresponds to the increase of the depth of singularity. The axial expansion of damage corresponds to the increase of the axial length of singularity. Similarly, when the local material of the pipe changes, the singularity corresponds to the part of the pipe where the local material changes. This part of the singularity material can be other material types that are inconsistent with the pipe material, such as the connecting part of a PVC pipe in two sections of steel pipe. Note that most detection methods of the pipeline leakage are post-leakage detection, which brings risks such as the wasting of resources. In this paper, the harmful energy of water hammer is taken as the excitation source of the pipeline, and the vibration characteristics of the pipeline are studied. The singularity characteristics of the pipeline relate to the vibration of the pipeline excited by water hammer, which provides a basis for the detection before the singularity becomes the leakage point. Based on COMSOL software, the fluid-free pipeline model and the water hammer excited flow pipeline model are constructed. Detection points are set to detect different characteristics (depth characteristics, axial length characteristics, and material characteristics) of pipeline singularity, and the influence of the singularity on the pipeline stress, pressure, displacement, and other parameters is studied. When the depth of singularity is 20%, 40%, 60%, and 80% of the wall thickness, the pipeline's maximum pressure increases with the increase of the depth of singularity; when the water hammer is applied to the pipeline, the depth of singularity increases, the pipeline's maximum stress increases, and the displacement at the singular point of the pipeline decreases. Compared with the depth of the singularity, the axial length of the singularity is 0.02, 0.025, 0.03, 0.035, and 0.04 m, respectively. It has a lesser influence on the pipeline characteristics than the depth of singularity. The material change of the singularity will also have an impact on the pipeline vibration, a factor which can be applied to the seismic design of pipelines. Detection before the singularity becomes a leak is the objective. These phenomena show that, based on vibration wave transmission characteristics, it is feasible in mechanism to achieve this objective. [ABSTRACT FROM AUTHOR]

The paper presents the current level in the development of an integrated system to ensure the security of the built space, with semi-automatic generation of PGA maps from seismic actions or other vibrating sources and rapid assessment of the vulnerability of instrumented/monitored buildings. The integrated and automated system is an essential step for the early detection of damage to future earthquakes. As performance benchmarks are listed: identification and acquisition of specialized software, an instrumentation campaign of public utility buildings belonging to NIRDs at national level, some case studies. The obtained results are transferable and of special technical and legal importance, the elaborated documents representing the basis for the Technical Book, and the archived data constituting initial records for the future data obtained after a major earthquake. Finding a reliable solution for a quick analysis after an earthquake, by generating a report with the dynamic parameters of the monitored buildings behaviour, is a challenge of a strategic and logistical nature, of acquisition, storage and continuous processing of data, elaboration of analytical models for validation, in context of digital approach for structural engineering. [ABSTRACT FROM AUTHOR]

Featured Application: This paper provides an innovative design of prefabricated shear wall that is suitable for industrialized construction. A restoring force model that reflects the hysteretic performance of the prefabricated shear walls with built-in steel sections is developed and a calculation method for cracking stiffness for prefabricated shear walls based on test fitting, mechanical calculation, and test modifications is proposed and evaluated. A calculation method of the ultimate load for prefabricated shear walls based on an ultimate equilibrium equation is developed. The results of this paper can be applied in developing design codes for prefabricated shear walls and serve as a reference for practical applications. Prefabricated shear walls have been widely used in engineering structures. Vertical connection joints of the walls are the key to ensure the safety of the structures. Steel–concrete composite structures have been proved to have a good bearing capacity and ductility. In this paper, a new type of prefabricated structure is proposed, in which vertical wall members are connected together through built-in steel sections and cast-in-place concrete. This paper studies the seismic performance of the proposed prefabricated concrete shear wall structure. Hysteretic curves and skeleton curves of the shear wall are obtained based on experimental analyses. A dimensionless skeleton curve model is developed using the theory of material mechanics and the method of regression analysis. A stiffness calculation method for different loading stages is obtained and a restoring force model is proposed. The proposed innovative prefabricated shear wall structure provides good resistance to seismic performance and the related analysis provides a fundamental reference for studies of prefabricated shear wall structures. [ABSTRACT FROM AUTHOR]

In the applications of supplemental dampers for seismic hazard mitigation, the supporting braces for the dampers are considered an important component for ensuring an efficient energy dissipation in the structure. Despite their importance, studies on the effects of the brace stiffness and the velocity exponent in the case of nonlinear viscous dampers are rather limited. In this paper, a numerical time-stepping method is developed for computing the seismic response of the structure with supporting braces and nonlinear viscous dampers. Using the proposed method, effects of the parameters of the nonlinear damper-brace systems are investigated, using first a single-story structure, followed by multi-story buildings. Results indicated that the design parameters for the dampers and supporting braces may be combined in numerous ways to satisfy a given set of structural performance objectives, but the brace stiffness can be minimized to achieve design efficiency in the range of velocity exponent commonly used for seismic applications of nonlinear viscous dampers. Results also indicated that for a set brace stiffness, if the dampers are optimally designed, the velocity exponent has an insignificant effect on the structural seismic performance objectives considered in this paper. [ABSTRACT FROM AUTHOR]

Scientists from different disciplines at ETH Zurich are developing a dynamic, harmonised, and user-centred earthquake risk framework for Switzerland, relying on a continuously evolving earthquake catalogue generated by the Swiss Seismological Service (SED) using the national seismic networks. This framework uses all available information to assess seismic risk at various stages and facilitates widespread dissemination and communication of the resulting information. Earthquake risk products and services include operational earthquake (loss) forecasting (OE(L)F), earthquake early warning (EEW), ShakeMaps, rapid impact assessment (RIA), structural health monitoring (SHM), and recovery and rebuilding efforts (RRE). Standardisation of products and workflows across various applications is essential for achieving broad adoption, universal recognition, and maximum synergies. In the Swiss dynamic earthquake risk framework, the harmonisation of products into seamless solutions that access the same databases, workflows, and software is a crucial component. A user-centred approach utilising quantitative and qualitative social science tools like online surveys and focus groups is a significant innovation featured in all products and services. Here we report on the key considerations and developments of the framework and its components. This paper may serve as a reference guide for other countries wishing to establish similar services for seismic risk reduction. [ABSTRACT FROM AUTHOR]

Bridges are among the key elements of the transportation network. Many bridges are severely damaged or destroyed when subjected to earthquakes. One of the effective methods to reduction of a bridge's seismic damage is to upgrade the seismic codes. Equivalent static analysis (ESA) is the most conventional method for the seismic design of bridges. Bridges can be classified into two groups based on the connection system between the superstructure and substructure, namely isolated bridges and integrated bridges. In this paper, the adequacy of the ESA method is investigated to estimate the seismic base shear force (BSF) of controlled (isolated) bridges and integrated bridges according to AASHTO, Caltrans, and ATC-32 provisions. For this purpose, three bridges are modeled in three dimensions. The effects of lead rubber bearings, friction pendulum bearings, and viscous dampers on the response of bridges are evaluated using eigenvector analysis, ESA, and nonlinear dynamic analysis. The results indicate that there are significant differences between the BSF estimated by the ESA method and in different provisions. The results of nonlinear dynamic analysis indicate that energy dissipation equipments can decrease the seismic response of structures. Also, the use of the ESA method can only be employed for an initial estimate of the BSF of vibration-controlled bridges. For the detailed study and design of bridges, the ESA method does not provide an accurate estimate of the BSF. This is why the use of the ESA method is not recommended. [ABSTRACT FROM AUTHOR]

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes. [ABSTRACT FROM AUTHOR]

The assessment of the seismic performance of transportation infrastructures is of primary importance for the management of the aftermath of an earthquake. To perform such an assessment, various modeling approaches characterized by different levels of accuracy are available and modern seismic design codes provide recommendations about their use. Non-linear time-history analysis (NLTHA) is acknowledged as the most reliable method, but is difficult to implement and is computationally expensive. This paper aims to investigate the viability of less complex methods, but with low computational cost, for the assessment of straight, multi-span bridges and compare their performance against the results of NLTHA in order to quantify the expected accuracy. The study is developed considering three bridge archetypes with either simply-supported or continuous-deck layouts, representative of typical features of the Italian bridge stock. The bridges are analyzed first through nonlinear dynamic analyses, to define the benchmark solution; then linear dynamic analyses, such as Linear Time-History and Response Spectrum Analysis, nonlinear static analyses, such as MPA (Modal Pushover Analysis), and Equivalent Static Analysis are considered. A comparison among the examined procedures is eventually proposed, highlighting the strengths and weaknesses of each approach. [ABSTRACT FROM AUTHOR]

Masonry has been widely used for the construction of residential buildings in Serbia and the majority of European countries. Confined masonry (CM) is a contemporary masonry technology that consists of load-bearing masonry walls enclosed in lightly reinforced horizontal and vertical reinforced concrete (RC) confining elements. CM has been widely used for the construction of low-rise and mid-rise residential buildings in Serbia and the region (Yugoslavia) since the 1960s. The design case study of a typical multi-family residential building located in Niš, Serbia (the third-largest urban center in the country), is discussed in this paper. This building was initially designed as a five-story CM structure in accordance with the 1981 Yugoslav seismic design code PTN-S, which was enforced in Serbia until 2019, when the Eurocode was adopted for official seismic design codes. Due to architectural constraints, the original design solution involving the CM system was not compliant with the code; hence, an alternative design using an RC-frame system with masonry infills was adopted. A comparison of two different design solutions provides insight into the different requirements of seismic design codes that have been used in the region. It is important to observe that seismic forces for RC structures determined in accordance with the PTN-S code are considerably lower compared to the ones determined according to EC 8-1, with the ratio ranging from 0.37 to 0.69. The seismic shear force according to Eurocode 8 is 1.46 times higher than the force that was used for seismic design according to the PTN-S code in the case of RC-frame structures. The results of an analysis of CM structures show that the seismic shear force in accordance with Eurocode 8 is almost 2.6 times higher than the force that was used for seismic design in accordance with the PTN-S code. The findings of this study are believed to be useful for understanding the difference in seismic design solutions for previous seismic design codes (which were used in the region for more than 40 years) and the present codes (Eurocodes). [ABSTRACT FROM AUTHOR]

This discussion is based on the paper by Chen et al. in 2023 (hereafter referred to as "the original paper/authors"). In their study, the original authors conducted a series of analyses using nonpulse, single‐pulse, and multipulse ground motion records, evaluating their impact on a frame structure, a slope, and a gravity dam. Their key finding suggests that multipulse ground motion leads to more severe structural damage compared to nonpulse and single‐pulse ground motions. However, it is important to note that the seismic damage analysis of the gravity dam in this paper does not adhere to state‐of‐the‐practice recommendations. Consequently, drawing a definitive conclusion regarding the influence and importance of multipulse ground motion records on the seismic response of concrete dams requires further justification. This necessitates the incorporation of high‐fidelity numerical models and probabilistic performance evaluation. We will discuss the significance of modeling assumptions, specifically addressing the dam–rock dynamic interaction in crack propagation and failure in dams. [ABSTRACT FROM AUTHOR]

This paper explores the performance of the reinforced concrete column and steel beam (RCS) structural system at the frame-level, with a focus on evaluating the seismic design coefficients (R -factor, Ω0, and C d ) using the FEMA-P695 methodology. The RCS system offers a more efficient and cost-effective solution compared to conventional steel and RC moment-resisting frames, with higher damping and lateral stiffness of RC columns and greater energy dissipation capacity of steel beams. Although several experimental and numerical studies have evaluated the performance of the RCS system, most of them have focused on the connection-level. In this study, 32 archetypes are designed with varying building height, span length, concrete strength, gravity load level, seismic load level, and column-beam strength ratio. Nonlinear analytical models are developed for the selected archetypes, and the modeling assumptions are validated through five distinct experimental tests. The models are then subjected to both static pushover and response history analyses, and the seismic design coefficients of the archetypes are evaluated and discussed based on the FEMA-P695 methodology. The results indicate that the design requirements of the RCS system are efficient, providing a high safety margin. However, the level of conservatism is found to be excessively high. Thus, it is possible to use a larger R -factor in the design process or make some relaxations in the design requirements related to this structural system. While further research should be carried out to validate the results, this study shows that as long as the R -factor is less than R = 10, the building can be deemed sufficiently safe for seismic loadings. [ABSTRACT FROM AUTHOR]

This paper focuses on the seismic response of symmetrical underground subway stations to seismic waves with varying frequencies and peak ground accelerations (PGAs), essential in light of growing urban underground transit systems. A 1/40 scale station model was subjected to seismic simulations using waves from the Wenchuan and Tangshan earthquakes and an artificial wave spanning 0.1 g to 0.5 g PGAs. Shaking table tests revealed that seismic impacts divide at PGA = 0.3 g; high-frequency waves affect structures more below this threshold, while low-frequency waves have more impact above it. The columns on the third basement level responded more to seismic activity, particularly at their base. The study recommends prioritizing the seismic design of these columns during station construction, especially in earthquake-prone zones. Understanding the dynamic effects of different frequencies and amplitudes is crucial for selecting and reinforcing materials and structural designs to enhance seismic resistance. [ABSTRACT FROM AUTHOR]

Seismic design guidelines for non-structural components typically do not account for the potential interaction between the vibrations of these elements and the deflections of the host structure, especially in the vertical direction. This paper examines critical seismic scenarios, such as the simultaneous vibrations from operating motorized devices (like chillers) and earthquake-induced movements, by considering the short-period spectral characteristics of vertical ground motion components in near-fault regions. To address this, the amplification factor of non-structural components installed in low-rise and mid-rise steel moment-resisting frame structures was assessed using nonlinear time history analysis. The evaluation showed that the amplification factor of vertical acceleration for non-structural components with vertical mode periods below 0.5 seconds ranged from 1 to 4, depending on the number of floors in the host structure and whether the motor was operational. The operation of the chiller's motor on the roof during an earthquake increased the vertical acceleration amplification factor by 10% to 50%. These findings suggest that the current seismic code approaches, which overlook the vertical mode frequency of structural and non-structural elements, need to be reconsidered, especially in near-fault areas. [ABSTRACT FROM AUTHOR]

Embankments in the field of civil engineering were historically not given much attention in terms of their ability to withstand seismic activity, as they were considered to be non-critical structures. However, in recent years, the seismic stability of embankments has gained increasing importance in the field of geotechnical engineering. This increased significance is due to the need to quickly restore functional infrastructure after earthquakes. The occurrence of lateral spreading, resulting from foundation liquefaction, is the primary factor leading to embankment distress in geotechnical engineering during seismic events. To address this issue, this study presents a novel approach that employs geosynthetic basal reinforcement. The research paper presents a technique that uses geosynthetic basal reinforcement to manage the lateral spreading of embankments both pre- and post-earthquakes, guaranteeing their ongoing effectiveness. The proposed approach utilizes a pseudo-static limit equilibrium method for determining the tensile load produced in the basal reinforcement. The serviceability criteria establish the maximum strain permitted in the basal reinforcement by imposing a restriction on the horizontal movement of the embankment toe. By taking into account the tensile load of the reinforcement and the maximum allowable strain, it is feasible to establish an appropriate geosynthetic reinforcement that considers various factors including tensile strength, strain, design life, installation, and durability impacts. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigations on the lateral performance of cross-laminated timber (CLT) shear walls with customized self-tapping screw (STS) connections. The panel-to-base (hold-downs and shear brackets) and panel-to-panel (spline) connections were tested under quasi-static monotonic and reversed cyclic loading to derive design values of STS, which were shown to be 2.8–3.6 times higher than those calculated using the current Canadian timber design standard. Then, a total of 26 CLT shear walls, including single-, double- and triple-panel configurations, were tested, again under quasi-static monotonic and reversed cyclic loading. The shear walls consisted of five-ply, 139-mm-thick and 3-m-high CLT panels with aspect ratio of either 2∶1 or 3∶1 , and different numbers of STS in the connections. The shear wall strength and corresponding displacements increased with the number of screws in hold-downs and spline joints; further, it increased with number of connected panels and decreased as a function of aspect ratio. The data can be used for developing and calibrating numerical models to investigate the lateral responses of CLT shear walls with different configurations. [ABSTRACT FROM AUTHOR]

This study analyzes the progression, utilization, and inherent challenges of traditional non-linear static procedures (NSPs) such as the capacity spectrum method, the displacement coefficient method, and the N2 method for evaluating seismic performance in structures. These methods, along with advanced versions such as multi-mode, modal, adaptive, and energy-based pushover analysis, help determine seismic demands, enriching our grasp on structural behaviors and guiding design choices. While these methods have improved accuracy by considering major vibration modes, they often fall short in addressing intricate aspects such as bidirectional responses, torsional effects, soil-structure interplay, and variations in displacement coefficients. Nevertheless, NSPs offer a more comprehensive and detailed analysis compared to rapid visual screening methods, providing a deeper understanding of potential vulnerabilities and more accurate predictions of structural performance. Their efficiency and reduced computational demands, compared to the comprehensive nonlinear response history analysis (NLRHA), make NSPs a favored tool for engineers aiming for swift seismic performance checks. Their accuracy and application become crucial when gauging seismic risks and potential damage across multiple structures. This paper underscores the ongoing refinements to these methods, reflecting the sustained attention they receive from both industry professionals and researchers. [ABSTRACT FROM AUTHOR]

To facilitate the precise design of earthquake-resistant structures, it is imperative to accurately evaluate the impact of seismic events on these constructions and predict their responses. OpenSeismoMatlab, a robust, free ground motion data processing software, plays a pivotal role in this endeavor. It empowers users to compute a wide array of outcomes using input acceleration time histories, encompassing time histories themselves, as well as linear and nonlinear spectra. These capabilities are instrumental in supporting structural design initiatives. This study provides a comprehensive exposition of the latest version (v 5.05) of OpenSeismoMatlab. It delves into intricate facets of the software, encompassing a detailed exploration of the input and output variables integral to each operational category. Comprehensive calculation flowcharts are presented to elucidate the software's organizational structure and operational sequences. Furthermore, a meticulous verification assessment is conducted to validate OpenSeismoMatlab's performance. This verification entails a rigorous examination of specific cases drawn from existing literature, wherein the software's outcomes are rigorously compared against corresponding results from prior studies. The examination not only underscores the reliability of OpenSeismoMatlab but also emphasizes its ability to generate outcomes that closely align with findings documented in the established body of literature. Concluding the study, the paper outlines potential directions for future research, shedding light on avenues where further development and exploration can enhance the utility and scope of OpenSeismoMatlab in advancing seismic engineering and structural design practices. [ABSTRACT FROM AUTHOR]

Despite the recent initiatives and developments in building design provisions using performance-based design, practicing engineers frequently adopt force-based design approaches, irrespective of the structural system or building irregularity. Modern seismic building codes adopt the concept of simplifying the complex nonlinear response of a structure under seismic loading to an equivalent linear response through elastic analytical procedures using seismic design response factors. Nevertheless, code-recommended seismic design response factors may not result in a cost-effective design with a uniform margin of safety for different structural systems. Previous studies also adopted different methodologies for quantifying the seismic response factors. Hence, there is a pressing need for a comprehensive review covering the developments in quantifying these vital design factors. This paper presents a systematic review of the response factors used with linear analytical procedures recommended by modern building design provisions and the techniques employed in previous studies to evaluate these factors using SDOF and MDOF systems covering analytical, experimental and hybrid assessment approaches. Limitations and gaps identified from the previous studies indicated that most investigations focused on 2D analysis and regular low-rise buildings, while limited studies were directed to shear wall structures, considering mostly unidirectional seismic loading. This comparative review provides insights into previous studies' methodologies and constraints and identifies the need for future research to calibrate seismic response factors to achieve more economical designs with consistent safety margins for different structural systems. [ABSTRACT FROM AUTHOR]

This paper introduces an updated formulation of a five-step procedure dealing with the design of fluid viscous dampers for the seismic retrofitting of existing frame buildings. The original design procedure is known as the "direct five-step procedure," and is articulated into 5 consecutive steps guiding the designer from the identification of the expected seismic performances, to the sizing of the added viscous dampers up to the final verification of the seismic behavior through nonlinear dynamic time history analyses. The procedure leads to the full definition of the mechanical characteristics of the commercial non-linear viscous dampers and allows to estimate the maximum dissipative forces acting in the dampers and the internal forces in the frame members. The objective of the design procedure, when applied to a new building, is to size the dampers in order to keep the structural elements within the linear elastic range considering a "rare" earthquake design level. However, when dealing with an existing building, especially if originally designed considering vertical loads only, the insertion of viscous dampers could be not sufficient to keep the structural elements in the elastic range. Thus, it might be necessary to accept local plastic excursion of the structural elements, by taking into account the ductility capacity (albeit probably limited) of the structural members (hysteretic dissipation associated with damage in beams and columns). This latter aspect is explicitly considered in the updated formulation of the "direct five-step procedure" presented here through the introduction of an overall response reduction factor accounting for both the ductility capacity of the structural members and the viscous damping provided by the added dampers. The design procedure is then applied to a 11- storey frame structure case study, which is representative of reinforced concrete buildings designed for vertical loads only. Three different retrofitting design strategies are considered, based on different exploitation of viscous energy dissipation provided by the dampers and hysteretic energy dissipation due to the excursion of the structural members into the inelastic regime. [ABSTRACT FROM AUTHOR]

The lateral resisting system comprised of hybrid shear walls is often met nowadays for high rise buildings, to reduce the lateral displacements of the building during a seismic event and to limit the damages of non-structural elements. In fact, "hybrid shear walls" term will replace the old terminology used for composite steel concrete shear walls. This structural system develops a very stable seismic behavior under cyclic lateral loads, but the seismic performance of the system could be significantly changed by the openings required for architectural or functional reasons. This paper presents in detail the seismic behavior of a composite steel-concrete shear wall designed with centered openings and partially embedded steel profiles in the edges. The composite wall was subjected to vertical and horizontal loads and tested to full failure using a cyclic loading testing procedure that simulated the action of an earthquake, aiming to record the seismic performance of the wall in terms of bearing capacity, deformation capacity, failure mode and stiffness degradation. The low-dissipative behavior recorded experimentally of the tested specimen was afterward validated and assessed in detail by performing numerical analyses using ATENA 3D Engineering software. The numerical results were extended to investigate furthermore other structural solutions to increase the bearing capacity and the seismic performance of the wall. It was found that a significant increase in deformation capacity could be obtained if the wall coupling beams are reinforced by diagonal steel bars or additional steel plates. [ABSTRACT FROM AUTHOR]

This research paper provides a simple and original approach to extend the resonant frequency tuning range for achieving high-to-low frequencies in electrostatically actuated microelectromechanical systems (MEMS) based resonators. In microstructures, low frequencies are usually achieved by increasing the effective mass or decreasing the mechanical stiffness. However, this work intends, assuming a double-sided electrodes design, to control the excited mode of the micro-system in order to achieve low frequencies through DC bias voltage variations and possibly eliminate the displacement dependency in capacitive micro-bridges-based structures. The design consists of a flexible microbeam where its equations of motion are derived within the framework of the nonlinear Euler–Bernoulli beam theory. The equations are then solved using the reduced-order modeling based on the Galerkin modal decomposition while considering the couple-stress theory. Simulation results show an improved performance of the proposed structure compared to previous studies. According to these results, a wide frequency tuning range has been achieved through a proper DC bias voltage arrangement. In addition, the outcomes of the numerical analysis were validated by comparing them with FEM results obtained by COMSOL software. [ABSTRACT FROM AUTHOR]

This paper proposes replaceable buckling-restrained flange cover plates to improve the seismic performance and resilience of steel frame joints. Five full-scale specimens were designed and tested under cyclic loads to investigate the hysteretic performance. The investigated parameters were the core plate thickness (affecting strength ratio α and thickness-gap ratio β) and restraining plate configuration (affecting restraining length ratio λ and restraining plate disconnected position ratio ψ). Numerical models were established using ABAQUS and verified through comparisons with experimental data and phenomena. The results show that the proposed joint can achieve the expected target of buckling-restraint and damage control. [ABSTRACT FROM AUTHOR]

Previous research has shown that using buckling-restrained braces (BRBs) at hinged wall (HW) base (HWBB) can effectively mitigate lateral deformation of steel moment-resisting frames (MRFs) in earthquakes. Force-based and displacement-based design methods have been proposed to design HWBB to strengthen steel MRF and this paper comprehensively compares these two design methods, in terms of design steps, advantages/disadvantages, and structure responses. In addition, this paper investigates the building height below which the HW seismic moment demand can be properly controlled. First, 3-story, 9-story, and 20-story steel MRFs in the SAC project are used as benchmark steel MRFs. Secondly, HWs and HWBBs are designed to strengthen the benchmark steel MRFs using force-based and displacement-based methods, called HWFs and HWBBFs, respectively. Thirdly, nonlinear time history analyses are conducted to compare the structural responses of the MRFs, HWBBFs and HWFs in earthquakes. The results show the following. 1) HW seismic force demands increase as structural height increases, which may lead to uneconomical HW design. The HW seismic moment demand can be properly controlled when the building is lower than nine stories. 2) The displacement-based design method is recommended due to the benefit of identifying unfeasible component dimensions during the design process, as well as better achieving the design target displacement. [ABSTRACT FROM AUTHOR]

In response to the increasing need for sustainable construction materials, numerous innovative timber-based structural systems have been developed in the past two decades. While timber-based shear-walls are popular, moment-resisting timber frames have received less attention in recent studies. However, with the availability of ductile and resilient beam-column joints (BCJs), timber frames can now be effectively used either independently or in combination with others. This study explores the feasibility of a dual system, consisting of cross-laminated timber (CLT) balloon shear-wall and glulam moment-resisting frame (CLTW-GMRF), and investigates the potential interaction between the two systems under seismic loading. The building features ductile and energy-dissipative BCJs and hold-downs. A seismic design procedure, based on a targeted moment proportion (MP) between the two systems, is presented and applied on a 10-story building. The building is assumed to be located in Vancouver, Canada, and its seismic performance is examined using 30 ground motion records in OpenSees. The system's efficiency with respect to engineering demand parameters is studied under different wall-to-frame MP values (50%–50% and 60%–40%) and ductility-related modification factors (2, 3, and 4). The study also investigates the system's performance with two BCJs and hold-down alternatives with bilinear hysteretic and self-centering energy-dissipative responses. Given the availability of resilient connections, the result highlights that the CLTW-GMRF coupled system is a viable alternative for high-rise hybrid timber construction. Moreover, the system's performance has significantly improved by using self-centering energy-dissipative systems. This paper unveils an innovative design approach and practical application for a CLTW-GMRF dual system. This innovative system incorporates energy-dissipative components that are designed and tested in existing literature: (1) the utilization of replaceable steel damper BCJs and buckling-restrained brace hold-downs, providing high ductility with large energy-dissipative capacity; and (2) the employment of hybrid BCJs made up of post-tensioned tendons and mild steel dissipators, along with hybrid brace hold-downs made up of pretensioned tendons and friction surfaces, which reduce residual deformations following seismic events. Utilizing these systems, the research introduces a versatile seismic design method congruent with existing codes and design standards, while offering flexibility through adjustable wall-to-frame moment proportions. The research also underlines the need for careful consideration of the interaction within the timber wall-frame systems. The implications are substantial amidst the growing trend of high-rise timber construction, aiming to fully exploit the potential of CLT and Glulam frames. Moreover, the research has the potential to serve as an essential resource for engineers aiming to optimize the sustainability and resilience of timber structures, particularly in seismic-prone regions. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of two welded unreinforced flange-welded web (WUF-W) beam-to-column connections that defy the current design paradigm of prequalified welded connections. The proposed WUF-W connections feature customized beveled backing bars that are intentionally left in place after the completion of the beam flange-to-column face complete joint penetration welds. The connection design aims at a stable hysteretic response by exploiting the beneficial aspects of appreciable panel zone shear yielding (i.e., inelastic shear distortions of at least 15γy , where γy is the panel zone shear distortion at yield), by considering a shear strength-to-demand ratio of 0.8. To prevent divot fracture in the column, minimum through-thickness toughness requirements were imposed for the steel column material. The experimental results suggest that the proposed WUF-W connections achieve a stable hysteretic response up until lateral drift demands of at least 7% rad, while a non-softening response was assured up to 9% rad. The beveled backing bars minimize the associated fracture potential near the beam web centerline, which is a primary concern in prequalified field welded moment connections when conventional weld backing bars are employed. The tests suggest that, under a symmetric cyclic loading protocol, local buckling near the steel beams is prevented up until a lateral drift demand of 6% rad, which is an important finding from structural repairability and stability standpoints. The ultimate failure modes of the welded connections, which are attributable to ductile crack initiation and propagation, are consistent regardless of the employed lateral loading histories, which involved standard symmetric cyclic and collapse-consistent loading protocols. The implications for the seismic design of steel moment resisting frames (MRFs) and the limitations of the present work are discussed. [ABSTRACT FROM AUTHOR]

The TOD mode with rail transit stations as the center has become an important direction of future central city construction. However, at present, there is still a lack of simplified calculation methods for the seismic design of a subway station complex structure of TOD mode. Based on the load-structure model of the classic response displacement method and the seismic deformation characteristics of the underground complex structure, an improved response displacement method for seismic calculation of the subway station complex structure considering the influence of the upper frame structure was proposed in this paper. Then, based on the actual engineering case, the applicability of the improved reaction displacement method was verified through investigating the influencing factors such as seismic wave type, ground motion intensity, building position, structure form, structure stiffness, and stratum stiffness. Furthermore, a series of numerical simulation experiments were conducted to verify the simplified method and further evaluate its computational accuracy. The result shows that the error in calculating the internal force and deformation response of a station complex structure by using the improved reaction displacement method can be controlled at about 10%. The improved response deformation method is proved to be a highly practical pseudo-static method. [ABSTRACT FROM AUTHOR]

In seismic risk assessment of bridges, developing fragility function is a fundamental step to characterize the structural vulnerability, which is usually derived based on the relationship between the engineering demand parameter (EDP) and intensity measure (IM). The EDP‐IM relationships are generally developed through three approaches, namely Cloud analysis (Cloud), incremental dynamic analysis (IDA), and multiple strip analysis (MSA). It is known that the Cloud method is computationally efficient while the IDA and MSA can provide the accurate fragility estimates. Thus, the present paper proposes an efficient and accurate fragility (EAF) approach which has similar computational demand as Cloud but keeps the same level of accuracy as IDA or MSA. In this proposed EAF procedure, the nonlinear time‐history responses at the intensifying duration of ground motions were used to develop the EDP‐IM curves. And these EDP‐IM curves are accurate enough to replace the IDA curves in developing fragility curves. To illustrate the efficiency and accuracy of the proposed EAF method, two typical bridges (a two‐span single‐frame bridge and a single‐pylon cable‐stayed bridge) were selected and modeled in OpenSees and employed as case studies. By comparing the fragility estimates of these bridges to IDA and MSA, it is demonstrated that the proposed EAF approach leads to reliable fragility results, while has similar computational time as Cloud. [ABSTRACT FROM AUTHOR]

The shaking table testing method on small sized models is one of the most effective approaches to study the overall seismic performance of various structures. Effective design of the scale model based on a rational scaling method can ensure the reliability of the test results. In this paper, the scaling methods are summarized into three levels: material similarity, component similarity, and structure similarity. A scaling method for steel‐reinforced concrete composite structures is proposed based on the component similarity, and experiments are conducted to verify the proposed method. The results show the flexural bearing capacity error between the model columns and prototype columns is within 20%, and both their force‐displacement curves and failure modes are consistent, which demonstrates the effectiveness of the scaling method. A 1/25 scale model of a steel‐reinforced concrete composite structure is designed based on the proposed method and tested on a shaking table to evaluate the seismic performance of its prototype. This research aims to provide a reference for the scaling method for shaking table tests. [ABSTRACT FROM AUTHOR]

Many of the procedures used in bridge design are force-based and may be considered reasonable design approaches that will lead to safe structures. But they do not directly address performance criteria at the initial stage of the design. On the other hand, the previously presented displacement-based design procedures of isolated bridges only considered the displacement of the deck, which means the pier's seismic performance and the substructure mass effects are ignored. This paper presents a new performance-based design method for isolated RC bridges considering the contribution of substructure mass. This method allows the designer that selects the performance level of the superstructure and substructure at the beginning of the design procedure. In this respect, the two degrees of freedom analytical model of the isolated bridge containing substructure mass is presented to quantify its effect on the performance of the seismically isolated bridge. The proposed design method is applied to two continuous-span bridges with regular and irregular substructures, and different target performance levels, including elastic and yielded substructures. The results of the proposed design method have been compared with nonlinear time history analyses, AASHTO, and National Cooperative Highway Research Program simplified methods. The results showed that the seismic performances are close to the results of the nonlinear time history analyses. However, the other design approaches, which ignore the substructure mass, underestimate the responses of the substructure. [ABSTRACT FROM AUTHOR]

High-quality seismic data is key to determining the success or failure of oil and gas exploration in complex mountain fronts. Observation systems are important factors affecting the quality of the seismic collection. Currently, the seismic collection design of piedmont zones is mainly based on optimizing and analyzing a single collection parameter. The multiparameter optimization is not performed as a whole. Moreover, the collection parameters that significantly impact the imaging quality of piedmont zones are not deeply excavated. This paper first uses the relationship between the acquisition parameters and the signal-to-noise ratio of a previous seismic data analysis to solve this problem and then obtains the prestack offset profiles of different acquisition parameters through forward modeling and prestack offset methods, further analyzes the acquisition parameters that have a more significant impact on imaging quality, uses the degenerative treatment method to process and analyze the newly collected seismic data, and delves into the most sensitive acquisition parameters for imaging quality. The results show that the influence of the gun line distance is the largest, and the influence of the receiving line distance, the number of receiving lines, and the number of receiving channels is reduced. Therefore, the effect of each acquisition parameter on the imaging quality is different, and different acquisition parameters should be selected according to the depth of the target layer. [ABSTRACT FROM AUTHOR]

Near-fault pulse-like ground motions can lead to significant seismic demand on building structures due to velocity pulses. The self-centering energy-absorbing dual rocking core (SEDRC) system is a newly developed seismic resilient structural system. This paper investigates the seismic demand of SEDRC systems subjected to near-fault pulse-like ground motions by determining their nonlinear displacement ratios. Two hundred and five near-fault pulse-like ground motion records are used to consider the uncertainties of seismic events. The influences of design hysteretic parameters and near-fault ground motion characteristics on the nonlinear displacement ratio of the SEDRC system are investigated through parametric dynamic analysis of single-degree-of-freedom (SDOF) systems. The dynamic analyses results indicate that the stiffness hardening ratio α and energy-absorbing ratio β of the SEDRC system, predominant period, pulse period of ground motions, and earthquake magnitude show obvious effects on the nonlinear displacement ratio responses of SDOF systems, while the unloading stiffness ratio ε, site condition, and source-to-site distance show limited or negligible influence on that. The past studies mainly used the mean or median responses of single-degree-of-freedom systems to predict the nonlinear displacement ratio of structures, which may not be enough to guide the design of buildings with great importance (e.g., hospital and fire station). This paper proposes an innovative framework for predicting the nonlinear displacement ratio of structures underground motions using a probabilistic estimation method and machine learning technique. Based on the dynamic analysis results of SDOF systems, a probabilistic model for predicting the nonlinear displacement ratio of the SEDRC system under near-fault pulse-like ground motions is developed through the proposed framework. The proposed framework is also applicable to estimate the seismic demand of other structures under near-fault or far-field ground motions to facilitate the development of the performance-based seismic design. [ABSTRACT FROM AUTHOR]

Featured Application: The grouted sleeve lapping connector in this work has the advantages of low cost and ease of construction, and it can realize full prefabrication of vertical components. In this paper, pseudo-static tests of L-shaped shear walls with high axial compression ratio are carried out to investigate the connection reliability of the joint under seismic action. The grouted sleeve lapping connector called the APC connector has the advantages of high fault tolerance, convenient construction, compacted grouting, and low cost, together with realizing full prefabrication of vertical components. In this paper, a quasi-static test of two fully prefabricated L-shaped walls connected with two types of APC connector and a cast-in-place wall was carried out under high axial compression ratio (0.5) to compare their seismic performance. The results indicated that the two types of connectors effectively transferred the rebar stress in the prefabricated walls, and the failure modes and final crack distribution of the prefabricated walls and the cast-in-place wall were basically identical. The failure of the cast-in-place wall occurred at the root of the wall limb, while the failure of the prefabricated walls occurred at the top of the sleeve due to the constraint of the sleeve. The bearing capacity, stiffness, ductility, and energy dissipation of the prefabricated specimen connected by the type-I sleeve was comparable to that of the cast-in-place wall, while the prefabricated wall connected by the type-II sleeve showed greater bearing capacity, stiffness, and ductility. Finally, some suggestions for seismic design of prefabricated components connected with APC connectors are proposed. [ABSTRACT FROM AUTHOR]

As a sustainable alternative to steel and concrete, cross laminated timber (CLT) shear wall systems are getting increasingly popular in mid-rise and high-rise construction, and that imposes new challenges on their seismic performance. The conventional connections used in this system, such as steel hold-downs and angle brackets, are, however, susceptible to brittle failures, thus being inappropriate for use in structures in seismic regions. A series of innovative connections have therefore been proposed in recent years for achieving better seismic behaviours in CLT structures, characterised by an adequate capacity, significantly improved ductility and dissipative capacity, as well as more controllable ductile failure modes. This paper first reviews the recent studies of CLT shear wall systems and conventional connections. Connection systems and shear wall reinforcement methods that have been recently proposed for seismic resilient CLT structures are then introduced, with their design strategies being summarised accordingly. The connections are then discussed comprehensively in terms of structural performance, manufacturability and constructability, employing similar criteria that have previously been proposed for steel modular connections. It is found that much improved ductility along with more predictable, ductile, timber damage-free deformation modes are achieved in most of the new connections. Some new connectors are designed with additional functionalities for optimised seismic performance or for easing the construction process, which, however, lead to complex designs that may add difficulties to the mass production. Therefore, comprehensive considerations are needed in connection design, and the discussion of this paper aims to assist in the future development of connection systems for seismic resilient multi-storey CLT buildings. [ABSTRACT FROM AUTHOR]

Karst landforms constitute one of the most harmful geological conditions, which have an adverse effect on the deep foundation structures of bridges. During earthquakes, the existence of karst caves can cause serious seismic damage to the bridge pile foundation. In order to investigate the seismic response of rock-socketed piles under vertical loads in complex karst cave conditions, finite element numerical simulation analyses were carried out, referring to the practical major bridge structure rock-socketed pile project in China. The peak strain distributions of rock-socketed pile foundation influenced by single-karst cave factors under the combined action of vertical loads and ground motions were investigated, and the influences of complex multi-caves were further explored. The results showed that the restraint effect of the bedrock near the pile would gradually decrease with the increase of the height of the karst cave and the decrease of the height of the karst cave roof; under the condition of a beaded karst cave, the constraint of bedrock between the karst caves makes the pile present the distribution characteristics of "multi-segment and multi-broken line"; under the condition of an underlying karst cave, the existence of the underlying karst cave would decrease the restraint of the bedrock at the bottom pile and increase the peak strain of the pile to a certain extent. This paper revealed the seismic response law of the rock-socketed pile under vertical loads within various complex karst cave conditions and developed reasonable reinforcement measures aiming at dangerous locations, providing important engineering guidance and a reference for the seismic design of rock-socketed pile foundation in complex karst areas. [ABSTRACT FROM AUTHOR]

The response spectra defined in the appropriate Euro standards from the first and second generation (EN 1998-1 and EN 1998-1-1), which determine the seismic load for common buildings, are critically presented first. To avoid a reduction in earthquake loading on structures using response spectra, only a few points of the response spectra in the second generation of EN 1998-1-1 are determined by applying the probabilistic concept of seismic hazard assessment. The comparison of current response spectra in EN 1998-1 is made with the uniform hazard spectra (UHS). The comment and application of the second generation of EN 1998-1-1 is a novelty that is introduced in this paper. On the basis of response spectra presented here according to EN 1998-1 and EN 1998-1-1 and other spectra obtained from real and artificial records, comparative different methods of analysis on one regular simple eight-story reinforced concrete frame structure are illustrated to find out how the kind of spectra and used methods of analysis influence the story displacements and story drifts of one simple regular structure. So, at the same time, the reader will be informed not only about novelties in the second generation of EN 1998-1-1 as far as response spectra are concerned but also understand the implication of various response spectra on the methods of analysis of building structures. [ABSTRACT FROM AUTHOR]

This paper describes the state of the art of structural steel reuse in Japan. A significant part of the material is taken from a document titled the Architectural Institute of Japan (AIJ) Recommendations for Sustainable Steel Building Construction (Draft) available only in the Japanese language. The motivations for and potential benefits of steel reuse are examined. The affinity between seismic design requirements and steel reuse is highlighted through a concept known as "damage-control" design. Some technologies for disassembly are introduced. The historical development and changes in Japanese structural steel are summarized, followed by a discussion on reusability of historical steel reclaimed from existing buildings. Reuse projects whose details are known to the authors are listed. The heart of the paper is a design procedure that specifies the structural engineer's role and involvement in planning, material procurement, and executing a steel reuse project. The discussion is concluded by six directions that should be pursued to make steel reuse a widely accepted reality in Japan. Among those directions are research needs to establish a procedure to quantify the remaining structural performance of reclaimed steel considering possible exposure to earthquakes, establish connections that allow for easy disassembly, and introduce modularized structural systems. High seismicity and the general practice to adopt full moment frames pose unique challenges for steel reuse in Japan. [ABSTRACT FROM AUTHOR]

An active type of upgraded tuned liquid column damper (AUTLCD) based on hedge-algebras (HA) theory is proposed to mitigate structural vibrations of seismic-excited buildings in this paper. The AUTLCD consists of an upgraded tuned liquid column damper (UTLCD) and an actuator to generate the control force, in which UTLCD is constituted by a traditional tuned liquid column damper (TLCD) fixed on an undamped tuned mass damper (TMD). In this study, the HA-based-on controllers are used to determine the value of control force through the state variables, including the displacement and velocity of the floor installing the actuator. This approach allows one to find the optimal parameters of UTLCD and the HA-based controller. The balancing composite motion optimization (BCMO), a novel and potential algorithm, is utilized for optimization problems in the paper. The effectiveness of AUTLCD is compared with an active tuned liquid column damper (ATLCD) having the same weight as the AUTLCD. The results obtained from this research indicate that AUTLCD is more effective than ATLCD for aspects of control performance and average control force. Furthermore, although the optimal HA controller is only designed for the El Centro earthquake data in 1940, it still offers a high-efficiency level for many other earthquakes. In addition, the HA-based controller also makes sure the system's stability in the operating process. [ABSTRACT FROM AUTHOR]

Modern analysis of earthquakes depends on digital time series; however, only about 30% of the timespan of recorded seismicity is available in digital format. During the first half of the 20th century, most of the earthquake ground motions in Mexico were recorded by Wiechert mechanical instruments on smoked paper. In this work, we developed and use Tiitba, a new portable multiplatform graphical user interface (GUI) open-source software coded on python, to vectorize and correct old analogue seismograms. Using this software, we vectorized the 11/1/1928 Parral (M6.3) earthquake seismograms to obtain the constant time-interval digitized time series for each component and station of the seismogram. Then, we obtained its source focal mechanism using a genetic algorithm methodology. Also, with an auxiliary Tiitba module, we constructed a SEISAN S-file to relocate the hypocentre of this earthquake. The obtained relocation is about 125 km south of a recently recorded seismic swarm that occurred in 2013, which has a similar focal mechanism to the one that we obtained in this work. [ABSTRACT FROM AUTHOR]

This paper investigates the creation and use of integrated IFC models to modernise traditional processes for applications to building authorities for structural engineering approvals and permits. First, we provide a brief overview of e-permit systems in the AEC sector, with the focus on solutions that implement openBIM standards like IFC, MVD, and IDM. Second, we conduct a study on the information requirements of Italy's seismic-authorisation processes relating specifically to the field of structural engineering. Third, we describe preliminary research on defining the structural engineering information that needs to be incorporated in the IFC format for e-permitting scopes. Fourth, we present our early work on the development of an MVD that would enable the automatic extraction of integrated IFC models. Fifth, we illustrate the reference workflow of the Str.E.Pe. project and propose a preliminary proof-of-concept that makes use of an IFC model, which has been integrated with structural information to support the activities of the building authority in Avellino. The of- ficers there have developed a SWOT analysis using IFC models to assist them in assessing the compliance of structural projects with seismic requirements. Finally, the paper sets out additional research we intend to undertake and our conclusions. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard assessment of North-East India is carried out considering the GMPE rule and framework developed in the companion paper to account for the propagation of epistemic uncertainty. Seismic hazard is characterized in terms of weighted mean and fractile representation using a logic tree approach. Target conditional spectra with different conditional time periods are estimated by two methods: considering GMPE-specific generalized causal rupture and all contributing causal rupture scenarios. Results are reported with 2475- and 475-year return periods. The ratio of fractile to weighted mean representation of hazard is proposed as an alternative viewpoint of the importance factor used in seismic design. [ABSTRACT FROM AUTHOR]

This article presents experimental data and nonlinear finite element analysis (NLFEA) modeling for an innovative buckling restrained bracing (BRB) system. The data were collected from qualification testing of introduced BRBs per the AISC 341 test provision and finite element modeling. The BRB is made of three parts: core bar, restraining unit, and end units, in which duplicates of three different core bar cross sections (i.e., fully threaded, threaded notched, and smooth shaved) were tested. The BRBs introduced in this research come with innovative end parts, so-called fingers. These fingers provide the longitudinal gap required in every BRB system and simultaneously prevent buckling of the core bar at the end regions at both ends of the BRB sample, thus facilitating an easy core replacement if it gets damaged in the event of an earthquake. The measured parameters were the applied cyclic load and the corresponding displacement. Analysis of the acquired data illustrated an almost symmetric hysteric behavior with a little higher capacity under compression but a noticeable overall ductility of 4. Moreover, finite element modeling data for one type of core bar (fully threaded) were curated. The data presented in this paper will be valuable for fabricating BRBs in practice and further research on the topic considered. Dataset:  http://doi.org/10.5281/zenodo.6795612. Dataset License: Creative Commons Attribution 4.0 International. [ABSTRACT FROM AUTHOR]

Earthquake events in recent years and their consideration in performance-based design have led to the development of increasingly sophisticated physical models in structural computations. The aim of such models has been to predict the structural behaviour when excited by an earthquake. In particular, in the context of nuclear power plants (high-risk structures), operators must justify the airtightness of ageing structures to study the nonlinear behaviours of these structures, requiring the study and modelling of the phenomena associated with seismic energy dissipation in concrete. Energy dissipation has been described at two levels: global and local scales. At the local scale, material behaviour laws express some phenomena, such as concrete damage, friction, unilateral effects or plasticity. At the global scale, for dynamic analyses, energy dissipation has been practically modelled with equivalent viscous damping. Rayleigh-type damping formulations are still the most commonly used in engineering. Numerous formulations have been proposed in the literature, and some papers have compared some of these formulations. However, comparisons have rarely been based on experimental data, and the structures studied have varied considerably among studies. Therefore, the first objective of this paper is to assess the accuracy of a wide range of damping formulations by comparing them to the experimental data. Reinforced concrete beams were tested in quasistatic mode on a strong floor and in dynamic mode on a shaking table. The aim was to study the energy dissipation involving nonlinear mechanisms in concrete while steel rebar remained in their elastic range. The study developed in this paper concerns the dynamic behaviour of reinforced concrete critical structures, which are over-sized in engineering, under moderate earthquake levels. Thus, a beam multifibre model is proposed with two different concrete constitutive models. The second objective is to compare the energy dissipation at structural and material scales to evaluate the most efficient damping formulations to represent dynamic nonlinear responses. [ABSTRACT FROM AUTHOR]

Time–frequency non-stationarity is a ground motion characteristic which is frequently neglected in current seismic design and research. This paper studies its impact on the seismic response of high-speed railway simply supported bridge (HSRSSB). A method for generating time–frequency stationary earthquakes (TFSEs) and time–frequency non-stationary earthquakes (TFNSEs) using wavelet packet transform is proposed. A finite element model of a three-span HSRSSB is established using OpenSees. The seismic response is obtained through non-linear dynamic time history analysis, and the fragility curves of bridge components and system are calculated through incremental dynamic analysis. Finally, the reasons for the differences are analyzed by comparing the differences in seismic response of bridge, component fragility and system fragility under two groups of ground motion. The results show that the time–frequency non-stationarity of ground motion has an effect on the bridge response and fragility under strong earthquakes. TFNSE will lead to larger ground motion response, and the damage probability of bridge components and systems is higher. The reason is related to the damage and period extension of bridges under ground motion. Structures with prolonged period anti-seismic measures need to pay attention to this effect. [ABSTRACT FROM AUTHOR]

The design of 3D seismic surveys continues to develop, but there have been few innovations in the design of 2D seismic surveys, despite their continued widespread use. In particular, the development of an approach to handling obstacles that may occur along the line, either requiring the line direction to be reoriented or small deviations applied. In this paper, I develop both an approach for determining the bend radius required when 2D lines require curves and compare strategies for dealing with small deviations. For the latter, the best approach is to move the source and receiver positions as close to the edge of the obstacle as possible with them placed on the same side. Irrespective of the approach employed, given the variation in the results shown here, the interpretation of 2D lines should always incorporate the acquisition geometry to ensure that misinterpretations are avoided. [ABSTRACT FROM AUTHOR]

The seismic design of building diaphragms is one of the most vexing tasks today. Diaphragms are the structural elements primarily designed to transfer in-plane forces to the lateral force-resisting system. Design challenges increase when modeling diaphragms in nonlinear response-history analyses. The main complexity lies in choosing a computationally efficient model and establishing the demands and force distribution throughout the diaphragm. This paper describes two commonly used methods and compares the results in the design forces. A reinforced concrete core-wall building with a flat-slab transfer diaphragm is presented as a case study. Diaphragms were modeled with linear shell elements and the stringer-panel model. Differences in the magnitude of the forces are not significant, although visible differences are observed in the presentation of the results. The stringer-panel model shows a clear and unambiguous load path for the in-plane forces, making it an attractive alternative for the analysis of diaphragms. [ABSTRACT FROM AUTHOR]

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

The swimming pool reactor (SPR) is an innovative and environmentally friendly heating source. An SPR building was selected as the research subject, and a 3D dynamic interaction model incorporating the liquid sloshing effect was created using ANSYS software and the secondary development characteristics of user-programmable features (UPFs). Energy dissipation from scattered waves was accounted for using viscous-spring boundary elements, while the dynamic hydraulic effect was modeled via the Housner equivalent mechanical model. Considering soil-structure interaction (SSI) effects, this study examines the impact of isolation measures on the structure's seismic mitigation performance. It investigates how varying foundation conditions affect the seismic resistance of the isolated structure. Results indicate that seismic isolation ratios for acceleration, floor response spectra, displacement, and base shear diminish as site stiffness decreases. However, regarding sloshing wave height, seismic isolation amplified the height under all conditions but remained within safe limits. These findings offer valuable insights for seismic design across different SPRs. [ABSTRACT FROM AUTHOR]