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Soil–steel composite structures are commonly considered competitive alternatives to conventional small road and railway bridges. The structure is made from corrugated steel plates and comes in various profiles and shapes, up to 32 m at most. These structures are also found in seismic areas. Despite this, knowledge of their seismic behavior is limited. The paper analyzes the seismic behavior of an existing soil–steel composite bridge in Poland, where full-scale tests have been conducted. The analyzed bridge has a total height of 6.05 m and a span length of 17.67 m and was built with 140×380 mm corrugation and 7-mm thick steel plates. Numerical analyses are performed on the bridge using the finite element (FE) program DIANA FEA with seismic records from the 1940 El Centro earthquake as a reference. Expanded polystyrene (EPS) geofoam is applied under the structure and studied in the numerical models to reduce the impact of seismic waves on the bridge. The first numerical model was created without geofoam for calibration purposes, and the latter five with EPS given different stiffness properties (densities and Young's modulus). The results suggest that EPS has advantageous features (especially with low stiffness) in reducing the maximum deformations and stresses on the steel shell by absorbing (damping) the energy of the seismic waves and rearranging the stresses away from the structure and to the soil. This trend was particularly evident when comparing the five models built with EPS to the model without EPS, where stresses in the structure were significantly higher, demonstrating the material's ability to rearrange the stresses away from the structure. Practical Applications: Soil–steel composite bridges are commonly considered competitive alternatives to conventional small road and railway bridges. The shell structure is made from corrugated steel plates backfilled by granular soil and comes in various profiles and shapes, up to a maximum of 32 m. These structures are also found in seismic areas. Despite this, knowledge of their seismic behavior is limited. This paper analyzes the seismic behavior of an existing soil–steel composite bridge. The EPS geofoams were applied under the structure and studied in the numerical models to reduce the impact of seismic waves on the bridge. The results suggest that EPS has advantageous features in reducing the maximum deformations and stresses on the steel shell by absorbing the energy of the seismic waves and rearranging the stresses away from the structure and the soil. The obtained results may contribute to the dissemination of these bridge structures in seismic areas. [ABSTRACT FROM AUTHOR]

Damage to buried pipes under seismic landslide actions has been reported in many post-earthquake reconnaissance. The landslide-pipe problem in the technical literature has been often investigated using simplified analytical methods. However, the analytical methods ignore the real mechanism of pipe response under natural dynamic slope instability. The dynamic slope instability is significantly influenced by its lateral boundary interface (LBI) characteristics. In this study, slope-pipe interaction (SPI) under seismic loading, focusing on the effect of LBI properties, is evaluated by continuum numerical simulation using the SANISAND constitutive model in FLAC3D. The results show that the geometry of the failure mass varies from 2D to 3D by increasing the stiffness at the slope boundaries (from smooth to hard) and the maximum pipe deformation decreases by around 40%. Moreover, the response components of maximum axial stress, bending moment, and shear stress of the pipe occur at the end sections of the buried pipe and near the boundaries of the landslide zone. However, the maximum pipe deflection occurs in the middle section of the pipe. The results of shear force-shear displacement curves demonstrate that the soil-pipe interaction stiffness is variable along the pipe length and can be estimated by a hyperbolic equation. [ABSTRACT FROM AUTHOR]

Previous research on seismic response analysis of dams primarily treated earthquakes as deterministic events; only a few studies on arch dams have explored earthquakes as random processes. This study introduces a three-dimensional seismic analysis of the Morrow Point arch dam, considering fully correlated random ground motion. The random ground excitation is characterized by the power spectral density function (PSDF) of the Kern County earthquake, for which the response time history is available. The spectral analysis technique describes the PSDF of the dam's response using the desired transfer function derived from Abaqus software. The analysis method is similar to that employed in finding the PSDF of the response of offshore structures from a given wave spectrum (PSDF). The method is validated by confirming the results of the proposed method with those of modal spectral analysis for empty dams and those of the time history analysis of the full reservoir dam. The results from the numerical study show that (1) the PSDF of responses obtained by modal spectral analysis using the first ten modes of the dam matches with those obtained by the direct analysis using transfer functions for the empty dam; and (2) mean peak arch stresses increases along the height of the dam from base to top, whereas mean peak cantilever stresses decreases; further, the mean peak arch stresses are less than the mean peak cantilever stresses at the base. [ABSTRACT FROM AUTHOR]

Seismic vehicle‐bridge interaction (SVBI) is the study of vehicle‐bridge interaction (VBI) in the presence of earthquake excitation. SVBI is an interdisciplinary problem of increasing importance to the design and safety of railways. This study deploys a consistent methodology to decouple the vehicle‐bridge system and solve independently the bridge and vehicle subsystems, bypassing multiple challenges the seismic response analysis of a coupled vehicle‐bridge system entails. The proposed approach builds upon the previously established Extended Modified Bridge System (EMBS) method for decoupling vehicle‐bridge systems (in the absence of earthquake excitation). Its premise is to first characterize and then assess the relative importance of the VBI effect on the bridge and vehicle responses and replicate it by modifying the pertinent uncoupled equations of motion (EOMs). The formulation deployed accommodates multi‐degree of freedom models for both the vehicle and bridge and can thus tackle complex systems. The analysis examines the ability of the proposed decoupling approach to predict the response of a realistic system vehicle‐bridge system under a suit of historical earthquake records. The decoupled results are in excellent agreement with the coupled solutions for all earthquake records and scenarios (i.e., earthquake excitation solely in the transverse direction of the bridge, as well as in both the transverse and vertical directions simultaneously). [ABSTRACT FROM AUTHOR]

The performance of various geogrid earth-retaining walls integrated with a non-cohesion granular backfill for reducing earth pressure has been investigated through small-scale shaking table tests and full-scale 3D finite element analysis. This purpose involved a series of physical modeling tests involving different earth-retaining walls (0.83 cm, height 7.5 cm, thickness, and length 1 m) and arrangements of full-scale 3D finite element analysis (5 m, height, 0.3 m, thickness, and length 6 m). This research investigates and designs hollow prefabricated concrete panels, gravity-type stone masonry, and reinforcement concrete (GRE) walls. It also displays comparative studies such as the top displacement of the wall, deflection of the wall, lateral pressure of the wall, settlement of the backfill, and vertical settlement of the foundation across the height of the (GRE) walls. The understanding and findings based on shaking table experiments and FE simulations have been used to develop a critical model for estimating earthquake-induced displacement (GRE) walls. The validity of the proposed FE simulation model has also been examined in the shaking table experiment and the FE simulation results. Based on the findings, the hollow prefabricated concrete panels were the most practical alternative due to their lower deflection and displacement. The observation also found that the hollow prefabricated (GER) wall is the most viable option, as the backfill surface settlement and lateral pressure decreased with the inclusion of geogrid reinforcement. [ABSTRACT FROM AUTHOR]

Wood and steel have different physical properties. By combining the two kinds of materials as bonded parallel beams, wood-steel frame structures can be prepared. This work considers the seismic performance of such engineering structures. Based on the Rayleigh damping model of substructures, the non-proportional damping coefficient is used to quantify the structural non-proportional damping characteristic of wood-steel frame structures. A complex mode superposition method is used to calculate seismic responses. Numerical cases showed that compared with the frame structure with upper steel and lower wood, the overall lateral performance is lower and the local lateral performance is higher for the frame structure with upper wood and lower steel. The overall lateral seismic design needs to be improved for the wood-steel frame structure with upper wood and lower steel. The local lateral seismic design needs be improved for the wood-steel frame structure with upper steel and lower wood. [ABSTRACT FROM AUTHOR]

An efficient time integration scheme has been devised for conducting time-history dynamic analysis of single-degree-of-freedom (SDOF) structural systems. The developed scheme belongs to Runge-Kuta family. The primary innovation of the new formulation lies in the constructive cooperation between the Hermite interpolation and the Gauss–Lobatto integration, linked to address the second-order ordinary differential equation of motion (DEOM). To put the idea into practice, several Hermite interpolators are generated to exploit the information of the internal points of Gauss-Lobatto integrator. The 4-point Gauss–Lobatto formula is employed to numerically integrate acceleration and velocity functions. This novel methodology has been designated the Gauss–Lobatto–Hermite 4-point (GLH-4P) method. GLH-4P furnishes a generally applicable implicit algorithm for conducting both linear and nonlinear analyses of structures subjected to seismic excitation. The advantage of the proposed algorithm over the conventional techniques is its higher accuracy level. Besides, it offers better stability compared with the conventional methods such as the Newmark-β and Wilson-θ methods. Unlike the other methods, GLH-4P can handle high-frequency systems without reducing the step size. Numerical examples reveal the efficacy of the GLH-4P method when juxtaposed against existing methodologies. [ABSTRACT FROM AUTHOR]

Due to limitations in traditional concrete gravity dam (CGD) design, a new approach is necessary. In this study, the lean analysis as a novel approach for CGD design, considering the interaction between dam and reservoir was considered. Maximum and minimum stresses at the heel and displacement of the crest were obtained as crucial input values of bubble sorting based on seismic analysis using Finite element analysis (FEA), and the Fuzzy Analytic Hierarchy Process (FAHP). The fuzzy bubble sorting analytic process, aimed at developing a novel method for selecting the best CGD configuration, was developed. Required Criteria, Sub-Criteria and developed models were applied to optimize the body of CGD. The weight of each sub-criterion and models were calculated based on pairwise comparison matrices. The novel approach was designed in MATLAB with the OPT-CGD code to select the best CGD model. The best weight of the Criteria, for selecting the best CGD model, based on the lean construction principles was selected from 60 developed models under implicit dynamic analysis. Statistical analysis reveals a 20% reduction in the concrete mass of the case study's optimal body compared to the traditionally designed dam. [ABSTRACT FROM AUTHOR]

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To solve the problem of large residual deformation and high repair cost of traditional frame structures after an earthquake, a new type of assembled shuttle-shaped self-centering mild steel energy dissipation brace (ASSSEDB) with stable stiffness, material saving, and easy replacement was proposed. The plastic deformation of mild steel is used to dissipate energy, and the disc spring system provides a reset function. Based on the working mechanism of energy dissipation brace, a restoring force model for the ASSSEDB was established, and then the numerical analysis was carried out by ANSYS to verify the accuracy of the proposed model. The results confirm that the ASSSEDB has stable energy dissipation ability and a resetting function, with a full hysteresis curve. The finite element analysis results align well with the developed restoring force model, and the maximum deviations of initial stiffness and ultimate capacity are, respectively, 1.4% and 2.3%, which indicates that the established restoring force model can provide a theoretical basis for design of the ASSSEDB. Furthermore, the time history analysis was carried out to assess the seismic performance of a six-story steel frame structure using the proposed ASSSEDB. The results show that compared with the steel frame structure with BRBs, the proposed ASSSEDB can decrease the residual deformation of structures by up to 93.41%. The self-centering ratio of the ASSSEDB is crucial in controlling residual deformation of structures, and it is recommended to be greater than 1.0. [ABSTRACT FROM AUTHOR]

The seismic assessment of concrete gravity dams is a problem of prediction of cracking and the corresponding consequences. With the widespread use of general-purpose finite element programs, the work in the field has shifted towards quantifying the behaviour in a framework for assessment. The nonlinear analysis and coupling with foundation–reservoir interaction, conversely, is still a challenging task. The modelling approach has significant effects on the analysis results and the assessment framework. The field remains an active area for research with many outstanding issues regarding damage quantification and assessment compared to any other major infrastructure component. A comprehensive overview of the seismic assessment of gravity dams is presented in this work with the goal to outline the issues in the field. Different models and modelling choices are compared in the context of damaged state assessment of gravity dams. The links between practical difficulties and theoretical issues are critically discussed. The aleatoric and epistemic uncertainties in the field, and their sources, are presented. Areas of future work are identified for improvement in seismic assessment as well as reducing and quantifying the uncertainties in the prediction of damaged states for concrete gravity dams. [ABSTRACT FROM AUTHOR]

In this paper, a series of incremental dynamic analyses were performed on five masonry towers resting on the base, whose geometry was taken from the literature, in order to determine how the difference in geometric characteristics and deformability of the subsoil affect the global behaviour, failure mechanism and seismic resistance of the towers. Special attention was attributed to determining whether masonry towers experience rocking motion mechanism during seismic excitation, which proved to be suitable in terms of seismic energy dissipation and earthquake resistance. Analyses were carried out using the planar numerical model based on the Combined Finite-Discrete Element Method (FDEM) at the macro level. The conclusions obtained on the basis of the conducted analyses can serve the researchers as guidelines to gain an insight into the expected failure mechanism of masonry towers for the assessment of their seismic resistance, as well as for making decisions about actions during their rehabilitation. [ABSTRACT FROM AUTHOR]

Timber–concrete hybrid structures are commonly employed in multi-story timber buildings; however, further research is necessary to fully understand the seismic performance of these structures as well as the dynamic properties of the floor. The two dynamic concerns, seismic effects and the vibration of floors in hybrid structures, are key issues, in view of which this study aimed to investigate the small-seismic-response spectra and elastic time histories in a high-rise timber hybrid building, specifically the medical technology building of Jiangsu Provincial Rehabilitation Hospital in China. The dynamic characteristics of a localized cross-laminated timber (CLT) floor were tested in situ, and the impacts of human-induced vibration were quantified. Comprehensive theoretical analysis results reveal that the basic vibration pattern of the structure was mainly translational in nature and that the period ratio, inter-story displacement angle, and shear-to-weight ratio all met the demands of the Chinese timber building design code. The experimental test results show that the vertical natural frequency of the CLT floor was about 15.96 Hz and thus met appropriate requirements with respect to natural frequency. However, peak floor acceleration was found to be high under the conditions of a single person walking quickly, a single person trotting, and multiple persons walking randomly. In light of these findings, the floor should be paved with a fine-grained concrete building surface, according to design requirements, so that its serviceability might be improved. Overall, the relevant analytical methods presented in this paper provide guidance and practical reference for the seismic analysis of timber hybrid structures, as well as vibration serviceability analysis for CLT floors. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to minimally modify a ground motion time history to induce collapse in nonlinear single‐degree‐of‐freedom systems (SDOF). The metric used to characterize the modification is the Arias intensity. The proposed procedure is a heuristic extension of a closed‐form solution derived to achieve a target maximum response in linear systems. The methodology is presented as a potential alternative to incremental dynamic analysis (IDA) widely used in earthquake engineering. [ABSTRACT FROM AUTHOR]

Abstract The performance of various geogrid earth-retaining walls integrated with a non-cohesion granular backfill for reducing earth pressure has been investigated through small-scale shaking table tests and full-scale 3D finite element analysis. This purpose involved a series of physical modeling tests involving different earth-retaining walls (0.83 cm, height 7.5 cm, thickness, and length 1 m) and arrangements of full-scale 3D finite element analysis (5 m, height, 0.3 m, thickness, and length 6 m). This research investigates and designs hollow prefabricated concrete panels, gravity-type stone masonry, and reinforcement concrete (GRE) walls. It also displays comparative studies such as the top displacement of the wall, deflection of the wall, lateral pressure of the wall, settlement of the backfill, and vertical settlement of the foundation across the height of the (GRE) walls. The understanding and findings based on shaking table experiments and FE simulations have been used to develop a critical model for estimating earthquake-induced displacement (GRE) walls. The validity of the proposed FE simulation model has also been examined in the shaking table experiment and the FE simulation results. Based on the findings, the hollow prefabricated concrete panels were the most practical alternative due to their lower deflection and displacement. The observation also found that the hollow prefabricated (GER) wall is the most viable option, as the backfill surface settlement and lateral pressure decreased with the inclusion of geogrid reinforcement.

This paper presents a seismic analysis method that can evaluate a very large number of cases for the free standing dry storage cask by proposing a methodology that has short analysis time as well as accuracy. This study also performed a seismic analysis of a dry storage facility with multiple casks to show a tip-over phenomenon from earthquake accident conditions. The earthquake accident condition is long-term event that occur during about 20 s long, and lots of seismic analysis cases should be performed to consider various real conditions because the free-standing spent-fuel dry storage cask has many nonlinear responses. The soil–concrete pad–cask interaction was considered in the seismic analysis and finite element model was made using concrete pad, soil and cask models. In the reinforced concrete pad, the rebar was excluded to reduce the analysis time, but the thickness was corrected to maintain the bending rigidity. Additionally, the analysis time reduced by modeling the cask as a rigid body rather than a flexible body. 35-cases of seismic analysis were performed to determine a tip-over phenomenon from each earthquake. The analysis revealed that no tip-over phenomenon of the cask was observed in all analyses from 0.2 g to 0.6 g, however the tip-over of the cask were observed from 0.8 g with friction coefficients of 0.8 and 1.0.

Abstract For the complexity and difficulty of seismic research on subway station structure system embedded in soft soil foundation, the seismic research method is quite different from the ground structure. The methods of seismic research on subway station structures in soft soil were summarized, and relevant literature on this field in recent years were sorted out. The advanced progress of theoretical analysis and quasi-static simplification analysis, model test (shaking table test, centrifuge test), numerical simulation (the total stress method, the effective stress method), and dynamic reliability of underground structures were mainly introduced for seismic analysis of subway station embedded in the soft foundation. The advantages and disadvantages of each method and the development direction of this field were proposed briefly in order to better understand seismic analysis of underground structure engineering in soft soil.

The seismic performance of a long-span triple-tower suspension bridge is a critical consideration in engineering communities. To promote a better seismic design, this paper presents a parametric study on the structural seismic control using hysteretic steel dampers. The finite element model is firstly established, and an introduction to the mechanical properties of the E-shaped hysteretic steel damper is made. Then, a seismic analysis is conducted under uniform earthquake excitations. Considering the effect of wave passage, the performance of hysteretic steel dampers in seismic control is further analyzed. The results indicate that the travelling wave effect greatly affects seismic responses. Increasing the damper elastic stiffness can effectively reduce the relative displacement between the main girder and either the left or the central tower. This treatment is effective for the right tower only when the wave velocity is among 400–1600 m/s, while it makes little contribution in other ranges. At an arbitrary wave velocity, increasing the damper elastic stiffness would cause minor changes to the shear forces of side towers, while its influence on the central tower is significant. A reasonable damper design for the long-span triple-tower suspension bridge depends on an essential prior evaluation of the wave velocity based on soil conditions. [ABSTRACT FROM AUTHOR]

The dynamic behavior of retaining walls is a complicated subject and a considerable design challenge, particularly under seismic conditions. Seismologists and investigators have an interest in near-fault earthquakes with significant velocity pulses because it can cause considerable displacements in constructions with respect to far-field earthquakes and consequently rise the hazard of earthquake-caused failure of structures. Despite there are several studies have investigated the seismic behavior of retaining structures, but the researches about retaining walls subjected to the influence of near fault like pulse earthquakes is still not adequate. The current study targets to numerically assess the dynamic performance of concrete cantilever retaining walls during far field ground motions (FFGMs) and near-fault ground motions (NFGMs). The nonlinear analysis of time history is conducted using the finite element method for three cantilever retaining wall models. The results of the analysis gained in terms of top horizontal displacement of the wall, active seismic earth pressure, and acceleration response of the system, which have been considered to recognize the impact of near fault earthquake on retaining structures. Additionally, the influence of different PGA of NF and FF earthquakes has been studied.

This study quantitatively evaluated the level of conservatism or accuracy of four typical directions used to assess the maximum structural response over all nonredundant seismic input angles: fault-normal and fault-parallel (FN and FP), the direct maximum direction (MD), the maximum peak ground velocity (PGV) direction, and the principal axes directions. Two eight-story models of symmetric and asymmetric buildings were developed, and two ensembles of ground motion records were selected considering three varying ground motion intensities. Bidirectional nonlinear response-history analyses (RHAs) were performed by rotating each pair of ground motion horizontal components to 26 orientations, from 0° to 170° in increments of 10° as well as four critical and their orthogonal directions. The effect of rotating the ground motions on several engineering demand parameters (EDPs) was investigated and the seismic demands in four critical directions were compared and evaluated deterministically and probabilistically. The four critical directions were re-evaluated by considering the largest response between two orthogonal pairs. The results show that the response in the maximum PGV direction is very close or equal to the maximum value over all orientations, especially for high levels of ground motion intensities, and thus is recommended for ground motion selection in performance-based seismic design and assessment. In addition, the influence of rotation angle is effectively reduced when using the larger seismic response value of the two orthogonal pairs while maintaining the same number of RHAs. [ABSTRACT FROM AUTHOR]

Numerical studies on freestanding structures typically leverage the Distinct Element Method where the response is dictated by joints; however, the response carries significant uncertainty due to joint stiffness parameters. This study aims to quantify the influence of joint stiffness parameters on the global response of freestanding structures subjected to seismic excitation in a probabilistic formulation. By using a range of joint stiffness values with rectangular rigid blocks of different aspect ratios, the impact of joint stiffness parameters is evaluated against a large suite of historical ground motions. Results indicate that increasing contact stiffness results in increased stability against overturning. [ABSTRACT FROM AUTHOR]

This study explores the feasibility of using fluctuations in the recurrence magnitude dispersion factor (b-value) as a seismic precursor for the Mizoram earthquake that occurred on November 26, 2021, in the Indo-Burma region of northeast India. Employing a comprehensive and homogeneous earthquake catalog spanning from 1900 to 2020, the seismic analysis involved delustering and completeness testing. The research implements a sub-sectional b-value calculation method, dividing the study area into uniformly sized grid cells (2° × 2°) and performing temporal b-value mapping for each grid. The epicenter of the Mizoram earthquake was located within a grid cell characterized by an intermediate b-value. Time-series analysis of the b-value indicated a notable decline preceding the main event, suggesting its potential as a seismic precursor. The study also examines depth-dependent variations in the b-value, revealing an inverse relationship between the b-value and crustal stress. To evaluate the significance of b-value anomalies, the Kolmogorov–Smirnov (K-S) statistic was employed instead of visual inspection. Additionally, the research provides probabilistic estimates of seismic hazard parameters, including the most probable maximum yearly earthquake, mean return period, and probabilities of earthquakes of varying magnitudes. These findings contribute to a deeper understanding of the complex seismotectonic framework and high lithospheric variability in the investigated region. [ABSTRACT FROM AUTHOR]

The increasing number of private cars, public transportation vehicles, and pedestrians, as well as the absence of adequate space for these ground amenities, are one of the primary causes of traffic congestion and accidents in the Kathmandu Valley. Investigations have indicated that the Kathmandu Valley has the greatest traffic accidents despite the heavy presence of the government and its agencies there. Most teens and young adults suffer injuries while using motor vehicles. The study's primary objective is to foresee and prevent such complications by planning for sufficient subsurface infrastructure (a cut‐and‐cover rectangular tunnel) for the Kathmandu Valley's transportation network. The overlying pressure, lateral earth pressure, live load, uplift pressure, and live surcharge are some of the forces acting on the tunnel, creating unique stress and moment zones. The tunnel meets the following geometric requirements: (a) Each of the tunnel's two cells has a clear span of 10 m and a clear height of 5.5 m. The side walls, inner walls, top slab, and bottom slab are all 700 mm thick. Soil has built up to a height of 4 m over the tunnel's roof. The analytical method is used in the tunnel segment's analysis. Furthermore, the designed tunnel has been evaluated for stability, considering the deflection and shear resistance. The analysis indicates that the tunnel meets the stability requirements. This implies that the structure is capable of withstanding the applied forces without excessive deflection. Non‐linear dynamic time history analyses of the El Centro earthquake and the Gorkha earthquake were computed. From the El Centro earthquake, the maximum displacement was 23.63 mm at 10.59 s, and from the Gorkha earthquake, the maximum displacement was 16 mm at 0.19 s for the modeled structures. [ABSTRACT FROM AUTHOR]

This study aims to assess the future structural performance of the Kozlu-Ulutan clay core rockfill (CCR) dam, one of the most significant water structures in the Black Sea region of Turkey, by utilizing 35 years of levelling measurements and 3D finite-difference analyses. Settlement measurements were obtained from five different points on the dam surface every 6 months. Subsequently, a three-dimensional (3D) model of the dam was created using the finite-difference method. Time-dependent creep analyses and seismic analyses were conducted sequentially, employing the Burger-Creep and Mohr–Coulomb material models, respectively. Non-reflecting boundary conditions were defined for the boundaries of the dam model. The 3D numerical analysis results were found to be highly compatible with the 35 years of levelling measurements. Additionally, the future seepage and settlement behaviors of the dam over a 100-year period (2023–2123) were analyzed, considering special time functions. Current and future seismic analyses were performed, taking into account the settlement results of the dam in 2023 and 2123. For seismic analyses, data from ten various earthquakes that occurred in Kahramanmaraş, Hatay, Malatya, and Gaziantep in Turkey in 2023 were utilized. The seismic analysis results provided significant information about the future seismic behavior of the Kozlu-Ulutan Dam, revealing notable differences between the current and future earthquake behaviors of the dam. Moreover, it was concluded that the clay core is the most crucial section concerning the current and future seismic behaviors of CCR dams. The study results emphasized the importance of continuous monitoring and periodic seismic evaluations for the safe operation of CCR dams. [ABSTRACT FROM AUTHOR]

Advancing the seismic resilience of building systems is an active area of research in earthquake engineering. Ensuring safe egress in and out of buildings during extreme events, such as an earthquake, is essential to supporting this effort. To this end, understanding the seismic response of stairs facilitates the robust design of egress systems to ensure they can remain operable after an earthquake. From prior earthquake events and physical experiments, it is understood that stairs with a flight to landing fixed connection at multiple levels within a building are prone to damage. In addition, the stair system with flight to landing fixed attachments may affect the dynamic behavior of the building. To accommodate seismic inter‐story drifts, a kinematically free connection between the stairs and landing has been proposed. Herein this connection is referred to as a drift‐compatible stair connection. To investigate and aid in the design of such a connection, a unique set of shake table experiments were conducted at the University of Nevada, Reno. In this paper, an overview of these tests is presented, and a high‐fidelity finite element model of the tested stair system is used to predict the responses measured during these experiments. Developed in Abaqus, the robustness of the modeled stair unit is investigated considering a variety of contrasting connections, namely, drift‐compatible connections, fixed ends and one end fixed and the other free. Results from these numerical simulations offer guidance towards development of simplified models of multi‐level stair subsystems. Such models are needed when investigating seismic resilience of building systems across a wider range of hazard levels. Furthermore, best practices observed utilizing the models developed and evaluated herein against experimental data will be useful for subsequent analysis of larger stair tower models, such as the 10‐story stair system implemented in the NHERI Tall Wood mass timber building with post‐tensioned rocking walls, conducted in 2023 at the UC San Diego Large High‐Performance Outdoor Shake Table. [ABSTRACT FROM AUTHOR]

A dynamic analysis of both twisting and regular towers is carried out to determine the results of considering soil-structure interaction (SSI) on high-rise buildings. In addition, the difference between the seismic performance of using twisting towers over regular ones is investigated. The twisting tower is a simulation of the Evolution Tower (Moscow). The towers' skeletons consist of RC elements and rest on a reinforced concrete piled-raft foundation. The soil model is considered as multi-layered with the same soil properties as the zone chosen for the analysis (New Mansoura City, Egypt). The only difference between both towers is their shape in elevation. The whole system is modelled and analyzed in a single step as one full 3D model, which is known as the direct approach in SSI. All analyses are carried out using finite-element software (Midas GTS NX). Dynamic output responses due to three records of seismic loads are proposed and presented in some graphs. Based on the results, it is concluded that SSI has a considerable effect on the dynamic response of tall buildings mainly because of the foundation flexibility, as it leads to lengthening the vibration period, increasing the story drift and the base shear for both cases. [ABSTRACT FROM AUTHOR]

A soil–water–air fully coupled numerical framework is proposed to predict the deformation and hydraulic behavior of soils under different saturation states in response to dynamic loading. The proposed framework is developed based on the mixture theory of porous media and the governing equations are discretized with the finite-element method. The soil behavior is modeled by a sophisticated constitutive model. The hysteresis characteristic and the mutual dependence between volume change and the degree of saturation in the soil–water characteristic curve (SWCC) are considered. A consistent description for both unsaturated and saturated soils is achieved by taking the effective stress and the degree of saturation as the two independent variables, with only one set of unified mechanical/hydraulic parameters. The numerical framework is first validated at the element level against undrained and unvented strain-controlled cyclic triaxial test results of unsaturated Toyoura sand. The reliability of the proposed framework in addressing boundary value problems is further validated by the simulation of a dynamic centrifuge model test. The numerical framework is further applied to the dynamic stability analysis of unsaturated embankments with different initial water contents. The results show that initially unsaturated embankments with relatively high water content are susceptible to liquefaction during seismic loading. There is a significant correlation between the liquefaction and the deformation-induced soil saturation. Deformation-induced saturation initially occurs at the toe of the embankment and then gradually extends to the areas near the lateral surfaces of the embankment, which triggers the development of shear bands. [ABSTRACT FROM AUTHOR]

Dams play a crucial role in water resource management, but the risk of failures requires a thorough safety evaluation. Earthquakes, among other factors, can contribute to dam failures, emphasizing the importance of securing the safety of both the dam and its associated structures against future earthquakes. While existing specification codes offer design ideas for seismic safety, dam-relevant structures have not received sufficient attention. This study focuses on the seismic analysis of the spillway and radial gate in Northern Thailand. The seismic behaviors of these structures are investigated using the finite element method, employing Nonlinear Response History Analyses to explore their seismic responses. Input ground motions for the analysis adhere to Thailand seismic design standard (DPT1301/1302-61), considering the Maximum Considered Earthquake (MCE). The results affirm that both the spillway and gate meet established safety standards, satisfying the prescribed criteria. Minimal damage is visible in the lower control bridge's pier. Radial gate stresses and deformations meet criteria, but stress is high in locally stiffened areas, and deformation is significant at unsupported points. Outcomes provide valuable insights, significantly contributing to the seismic safety analysis of the spillway and radial gate. These complex and unique findings emphasize the significance of implementing tailored measures to ensure the structural integrity, safety, and resilience of dam-related structures. [ABSTRACT FROM AUTHOR]

Reinforced Concrete (RC) buildings often rely on masonry walls to increase their rigidity and strength, distinguishing them from bare frames. Consequently, the lateral capacity of the RC frames is significantly impacted by the presence or absence of these walls. Numerical models are fundamental to understanding this behavior interaction, but the development of robust simplified models is still scarce. Based on this motivation, the reliability of a simplified numerical modelling approach was examined in this study and compared to several experimental tests. An optimized approach was implemented to determine the strut parameters, rather than relying on existing empirical formulae. The reliability of the initial stiffness, maximum strength, and energy dissipation was studied. From the results, the accuracy of the considered modelling strategy can be observed in different types of masonry elements (strong and weak units) with and without openings. The validated simulation approach reveals that the adopted macro-modelling procedure can accurately represent the behavior of infilled masonry frames. The maximum deviation of the prediction of the initial stiffness and maximum strength was found to be around 23% and 14%, respectively. These findings illustrate that the strut model effectively replicates real behavior with a satisfactory level of accuracy. However, using a consistent formula to define the strut can result in significant errors, particularly in strut width. [ABSTRACT FROM AUTHOR]

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

This article discusses the seismic isolation design and analysis of a complex medical building in China. The study aims to reduce seismic damage and improve the post-earthquake resilience of the building. The building adopts a frame-shear wall structural system and utilizes various types of seismic isolation bearings. The effectiveness of the seismic design is verified through calculations of natural vibration periods and seismic response. The study concludes that the seismic isolation design can significantly reduce the seismic response of the building and meet current code requirements. [Extracted from the article]

This paper presents an in-depth analysis of the Kopčić House, a significant example of modernist architecture in Sarajevo, Bosnia and Herzegovina, focusing on its structural-specific features and seismic performance. The Kopčić House embodies a confined masonry structure with innovative construction features, combining load-bearing masonry walls with reinforced concrete elements. This architectural approach was pioneering for its time, combining traditional construction methods with innovative materials and techniques. Detailed analysis using numerical modeling techniques, specifically 3D modeling with the 3Muri software (Vers.14.2.0.4), was conducted to assess the seismic resilience of the structure. The analysis considered different load distributions and eccentricities to comprehensively evaluate the building's response to lateral forces. The findings of this research reveal the structural capacity and potential vulnerabilities of the Kopčić House when subjected to seismic events. While the building demonstrates inherent strength due to its confined masonry design, areas requiring structural strengthening were identified through numerical simulations. This study contributes to the broader understanding of confined masonry construction within the context of modernist architecture. By integrating historical research with advanced structural analysis, this work aims to bridge the gap between architectural heritage and contemporary engineering practices. [ABSTRACT FROM AUTHOR]

The paper analyzes the application of the numerical findings of the program, which is becoming increasingly difficult for civil and structural design. Since, as in many other countries, the verification of design using a software model is now required by current Italian codes as well. Given this, the structural engineer must provide a technical report using a licensed software tool, attached to other project documents to get the Seismic Authorization at the local Civil Engineering Department offices. Following a brief explanation of structural analysis methodologies, this study presents a criterion for assessing the applicability of numerical findings obtained using any structural software. Three case studies of this criterion are shown to demonstrate how to check them using simple manual calculations: (i) the normal stress in RC columns subjected to gravity loads; (ii) the periods of vibration, participating masses, and seismic base shear derived from dynamic modal analysis; and (iii) the main parameters characterizing the pushover curves of existing buildings. Finally, this work underlines the significance of confirming the application of numerical results obtained by software in civil and structural design. The offered criteria and scenarios exhibit realistic techniques to ensure accuracy and reliability in structural performance assessment, according to the structural requirements imposed by current codes in Italy and similar countries. [ABSTRACT FROM AUTHOR]

The mutual behavior between the response of structure and soil, named soil-structure interaction (SSI) may become significantly important to be considered when structures are founded on deformable soil. In particular, critical infrastructures like nuclear power plants (NPPs) are particularly vulnerable to the consequences associated with the failure of any structural components because of the mutual interaction between the structure and the soil. In addition, soil mechanisms under strong earthquakes are highly non-linear and this reflects the discordance among the researchers for the selection of the most representative analysis model of nuclear structures. In this article, the role of SSI is assessed by presenting a critical discussion of the contemporary methods performed for the seismic analyses of NPPs. In particular, the paper proposes a discussion of the key issues that might facilitate the overall understanding of SSI phenomenon in case of NPPs.

Seismic risk is one of the biggest challenges for tunnel safety, and several mitigation techniques have been proposed to enhance the seismic performance of existing tunnels. This paper aims to investigate the effectiveness of an innovative approach for reducing the seismic risk of existing tunnels by using soft material walls (SMW) symmetrically installed in the surrounding soils. The investigation is performed with a two-dimensional numerical model and the effectiveness of SMW in mitigating the seismic-induced lining forces is quantitatively evaluated by reduction ratio. The influences of nonlinear properties of soil, SMW and tunnel lining on the isolation effectiveness are also discussed. The parametric studies show that the computed reduction ratio is strongly affected by the modulus ratio between the SMW and the soil, the wall geometric parameter, and the flexibility ratio. It is more effective for the thick and soft isolation walls that are inserted near a stiff tunnel in the soft soil. The tunnel seismic response can be reduced by up to 50% for the scenarios investigated. Notably, the parametric study identifies an optimum normalized depth of SMW and recommends a relation between the maximum isolation effect and the flexibility ratio. Finally, simple charts are suggested in this work for estimating the isolation effect in specific conditions of the soil and the tunnel. Along these lines, the results of this work may be used in the seismic retrofitting of an existing tunnel, aiding the preliminary design of the isolation walls.

Through the past few months, our world witnessed and is still suffering from several severe earthquakes in different places around the globe like Turkey, Syria, and Morocco. Therefore, the seismic activity domain grew the center of attention for researchers, engineers, and even regular people. The most significant topics in this field that must be taken into consideration are soil–structure interaction (SSI) and structure–soil–structure interaction (SSSI). The term SSI refers to the connection among structure, foundation, and soil while the term SSSI refers to the link among adjacent structures with the soil. Formerly, these subjects were not taken into account through the numerical and analytical methods utilized for the dynamic analysis of the seismic response of the structures (i.e., the effect of soil was ignored), and this matter led to disastrous costs that included loss of lives and properties. This article intends to offer an inclusive helpful knowledge of some significant factors that were not taken into consideration in the previous studies and can be utilized in the field of seismic analysis and design for minimizing the possible risks of earthquakes particularly the heavy ones by defining the SSSI behavior of adjacent structures due to these factors. To accomplish this goal, a sequence of seismic examinations via a shaking table system will be performed taking into consideration the impact of soil media. These tests will inspect the effect of the structure’s orientation and distance between them on the dynamic response of two close steel structures predicating on sand soil. The orientations selected here are of two types: the first one is parallel to direction of the earthquake wave and the second one is perpendicular to direction of the earthquake wave. Each orientation will contain three tests of three distances: close distance, medium distance, and far distance. Two novel small-scale multi-degrees of freedom steel models of three storeys are utilized in this study. Test results illustrated that the diversity of buildings orientation with distances has a significant effect on the SSSI behavior of the neighboring buildings. It is seen that the orientation perpendicular to the direction of the earthquake wave offered maximum impact on the dynamic responses at the far distance while the parallel orientation gave ultimate effect at the medium distance.

Rockbursts have become one of the most serious hazards in underground mines worldwide. While the characteristics of ground motions before rockbursts (or high-magnitude events (HMEs)) have not been studied. In this study, the peak ground velocity (PGV) and cumulative absolute displacement (CAD) before HMEs were examined based on seismic monitoring in a coal mine. It’s found that the source mechanisms vary significantly across different zones of the longwall, attributed to the low correlation between rock fracture types, stress levels, and seismic intensity. This correlation is mainly related to the distribution of primary fractures within the rock mass. The non-overlap of CAD peak with HME and the induction of delayed rockbursts are mainly caused by the unavoidable creep and additional energy input into the coal mass under disturbances before instability. The energy conversion process of the entire system is determined to be controlled by the stiffness ratio between the roof-floor system and the loaded coal, in accordance with the concept of dynamic and static load superposition. A high static load, strong dynamic disturbances, and a low rigidity ratio between surrounding rock and coal are identified as the most hazardous factors.

This study evaluated the stability of circular tunnels constructed in anisotropic granular soil in the presence of surcharges on the ground surface and seismic loads. The stability problem was solved using the lower bound limit analysis method in conjunction with the finite-element technique. In addition, the modified pseudodynamic technique was employed, which permits seismic accelerations to vary with depth and time, including the impact of amplitude and phase differences between shear and primary waves. The forces exerted by the soil on the tunnel lining vary over the perimeter. Therefore, the ultimate support pressure should at least be equal to the maximum normal stress from the earth surrounding the tunnel. It was discovered that parameters such as the tunnel cover depth, tunnel diameter, magnitude of surcharge, soil friction angle and its degree of anisotropy, seismic acceleration coefficients, period, and frequency of seismic waves determine the support pressure's magnitude and location. The influence of surcharge diminished beyond a certain cover depth and diameter ratio for given soil and seismic wave parameter magnitudes. This study showed that the maximum normal stress was 8.5 times greater than the uniform stress distribution. Furthermore, the support pressure was found to be a maximum of about 45.5% higher for a tunnel cover depth-to-diameter ratio of 3 than for 1%, 34% higher for anisotropy than for isotropic case, 25% higher in the presence of ground surcharge than its absence, and 60% higher for the horizontal acceleration coefficient of 0.3 compared to the static case. [ABSTRACT FROM AUTHOR]

Using the steel strongback braced (SB) system to seismically strengthen and retrofit reinforced concrete moment frames (RCMFs), this research aims to enhance the effectiveness of RCMFs. In this study, RCMFs of 5-, 10-, and 15-stories were designed according to the first and fourth editions of the Iran Earthquake Standard 2800. The RCMFs designed for the first edition are strengthened and reinforced using the strongback braced system. The studied structures were analyzed under incremental static loading and time history analysis. The findings indicate that the yield force and maximum base shear of structures designed using the fourth edition have increased by a range of 1.28–1.42 compared with those designed with the first edition. This underscores the imperative to enhance the structural integrity of buildings constructed according to the first edition. Meanwhile, the results of retrofitted structures with strongback braces show the same or better performance than newly designed structures. This indicates that this retrofitting system has a favorable effect on uniform drift control. A reduction of 33%–44% in story drift was observed when the SB system is added to the first edition's structure. [ABSTRACT FROM AUTHOR]

With the rising demand for hydropower energy, China has built numerous concrete‐faced rockfill dams (CFRDs) with considerable heights. The potential failure pattern of the concrete face slab is the key to the safety of the anti‐seepage system. However, engineers commonly employ an elastic relationship to model the concrete face slab for simplicity, which induces inaccurate estimation of the face slab's stresses, especially under seismic conditions. On the other hand, the existing elastoplastic models for concrete often require complex derivation of the necessary formula and thus are difficult to apply to finite element (FE) analysis. Under the comprehensive action of the upstream water, supporting rockfill, and surrounding mountains, the damage mode of the quasibrittle concrete slab is not a tensile mode but a compressive shearing mode. Therefore, it is urgent to establish an elastoplastic model that is adapted to the actual working environment of the slab and easy to apply. To this end, a generalized plasticity model is developed within the phenomenology modeling concept, which is validated at both the experimental level and application level. The results indicate that three‐dimensional stress‒strain behaviors, such as the strength nonlinearity, prepeak dilatancy, and postpeak softening, can be effectively captured. In addition, the seismic characteristics of a 200‐m high CFRD are numerically investigated. The findings show that the slab's stress accumulation can be reflected during the earthquake and that the final stress distribution conforms to the field observations. The conclusions of this paper provide a reliable reference for the seismic resistance design of CFRDs. [ABSTRACT FROM AUTHOR]

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Advances in nonlinear dynamic analysis of dams have not completely resolved concerns over modeling confidence and analysis accuracy. Verification and validation offer accuracy assessment, but uncertainties persist during performance evaluation due to both epistemic (modeling) and aleatory (parametric) sources. Epistemic uncertainties arise from simplifications and modeling techniques. This paper addresses epistemic uncertainties in a gravity dam seismic analysis using data from the International Comnission on Large Dams (ICOLD) benchmark study. While the benchmark formulation included the finite element model of the dam, mechanical material properties, and dynamic loads, participants retained the flexibility to opt for best‐practice modeling assumptions, simplifications, and other specifics. Notable response variability emerged, particularly in crack profiles and damage predictions. This study examines sources of variability, quantifying modeling uncertainty for the benchmark problem. More specifically, the modeling variability is quantified using the logarithmic standard deviation, also known as dispersion. This metric enables its incorporation into other seismic risk assessment and fragility studies. Under relatively low‐intensity motion (peak ground acceleration [PGA] of 0.18 g in this case), modeling dispersion of 0.45, 0.30, 0.32, and 0.30 were calculated for the maximum dynamic crest displacement, maximum hydrodynamic pressure at the heel, heel and crest maximum acceleration, respectively. Additionally, the dispersion of the failure PGA was determined to be 0.7. Findings underscore the need for systematic seismic response modeling in dam engineering to enhance prediction accuracy. A better understanding of the sources and magnitudes of modeling uncertainties can help improve the reliability of dam seismic analysis and contribute to the development of more effective risk assessment and mitigation strategies. [ABSTRACT FROM AUTHOR]

Abstract The increasing number of private cars, public transportation vehicles, and pedestrians, as well as the absence of adequate space for these ground amenities, are one of the primary causes of traffic congestion and accidents in the Kathmandu Valley. Investigations have indicated that the Kathmandu Valley has the greatest traffic accidents despite the heavy presence of the government and its agencies there. Most teens and young adults suffer injuries while using motor vehicles. The study's primary objective is to foresee and prevent such complications by planning for sufficient subsurface infrastructure (a cut‐and‐cover rectangular tunnel) for the Kathmandu Valley's transportation network. The overlying pressure, lateral earth pressure, live load, uplift pressure, and live surcharge are some of the forces acting on the tunnel, creating unique stress and moment zones. The tunnel meets the following geometric requirements: (a) Each of the tunnel's two cells has a clear span of 10 m and a clear height of 5.5 m. The side walls, inner walls, top slab, and bottom slab are all 700 mm thick. Soil has built up to a height of 4 m over the tunnel's roof. The analytical method is used in the tunnel segment's analysis. Furthermore, the designed tunnel has been evaluated for stability, considering the deflection and shear resistance. The analysis indicates that the tunnel meets the stability requirements. This implies that the structure is capable of withstanding the applied forces without excessive deflection. Non‐linear dynamic time history analyses of the El Centro earthquake and the Gorkha earthquake were computed. From the El Centro earthquake, the maximum displacement was 23.63 mm at 10.59 s, and from the Gorkha earthquake, the maximum displacement was 16 mm at 0.19 s for the modeled structures.

The aim of this paper is to give a comprehensive awareness of some substantial factors including the influences of the embedment level of a building and the presence of dead loading which affect the structure-soil-structure interaction (SSSI) of nearby buildings that were not investigated thoroughly in the preceding studies related to seismic analysis and design, and earthquakes hazards assessment. In order to achieve this goal, two dynamic tests will be implemented on two novel small scale multi-degree of freedom nearby steel models of six stories by a shaking table system with the consideration of soil participation in these tests; the first test includes examining the effect of several levels of embedment of one of the adjacent buildings, the second test includes examining the effect of the presence of dead loading for different situations. Test results indicated that these factors have critical impacts on the SSSI response. It is evident that the increase in embedment level led to mitigate the impact of the earthquake wave on the seismic response of the examined structure while the results of the dead loading conditions had some positive and negative aspects on the seismic responses of the tested structure. Regarding the foundation rotation and soil pressure responses, the outcomes also displayed an equivalent tendency to the previous two responses which included that as soon as the embedment level of the examined building maximized, these responses got minimized as well. The reduction was 13.1%, and 21.3% for the one-story embedment, and two-story embedment.

In this paper, modal effective mass for asymmetric fluid-structure interaction system is defined and equations for its calculation is derived. To establish consistency, modal effective mass in symmetric structure only system is briefly reviewed, followed by a definition of the modal effective mass in asymmetric system. The equations for calculating modal effective mass in asymmetric system are derived by utilizing the properties of left and right eigenvectors. To simplify the equations, the assumption is made that the mass matrix is only affected by the fluid. The simplified equation is then compared to the equation already used in ANSYS. Finally, the validity of the modal effective mass definition and derivation in this paper is demonstrated through a simple example.