To study the vibration influence of urban rail transit on buildings along the line, a frame-shear wall structure near a subway was selected as the research object. Under the excitation of rail transit vehicles, vibration monitoring of typical buildings was carried out at the foundation, along the height direction and the horizontal direction of the building, and the evaluation criteria such as 1/3 octave plumb vibration acceleration level, peak acceleration, and plumb fourth power vibration dose value were used for the analysis. The research results indicate that when the structure is 55 meters away from the inner contour of the tunnel, significant subway-induced vibration can still be detected inside the structure, and the relevant evaluation values may exceed the regulatory limits. In addition, the existing regulations do not specify the selection criteria for subway vibration, and the evaluation quantities determined by different value methods may seriously underestimate the impact of subway-induced vibration. Along the height direction of the structure, the vertical vibration response of the measurement points from the first underground level to the third above ground level did not significantly decrease, and there may be amplification at the top. The vertical vibration at the center of the floor slab is significantly amplified compared to the edge of the floor slab. The plumb fourth power vibration dose value at the center of the slab can reach 345% of that at the corner of the slab, and the corresponding maximum vertical vibration acceleration level can increase by 12.9 dB.

On December 18, 2023, a M_s6.2 earthquake occurred in Jishishan County, Gansu Province, affecting 118 towns including Dahejia Town, Liuji Town and Shiyuan Town. The areas have a relatively low level of economic development, with widespread and severely damaged brick (earth) and wood structures, resulting a significant number of casualties. In view of the large stock of brick-wood buildings in the region and their local characteristics, this study summarizes the architectural and structural characteristics of double-slope brick-wood structures and single-slope high wall brick-wood structures based on the on-site research, analyzes the typical earthquake damage phenomena and mechanisms, discusses the seismic vulnerabilities of existing brick-wood structures, and proposes the corresponding improvement measures in combination with the actual needs of rural construction. The findings indicate that in the epicentral area, most of the brick-wood structures are moderately damaged or severely damaged, and a few are destroyed. Structures with a mix of brick column and earth wall load-bearing and single-slope high-wall structures suffered more severe damage compared to double-slope brick-wood structures. The damage can be classified into four categories including overall or partial collapse, roof damage, wall damage, and other damage. The primary causes of the damage are identified as irrational structural systems, low mortar strength, poor overall integrity, and the absence of effective seismic construction measures. Consequently, this paper suggests targeted improvement measures to enhance the overall integrity, increase the collapse resistance of the walls, and prevent the collapse of roof components. These measures aim to provide a scientific basis and practical guidance for improving the seismic resilience of rural dwellings and optimizing disaster prevention and mitigation strategies.

The elastic foundation typically exerts a suppressive effect on the vibration response of the supported structure, and the influence of the soil-structure interaction effect on the dynamic characteristics of the structure exhibits typical nonlinear energy sink characteristics. At present, more and more attention has been paid to the dynamic research of elastic foundation beams considering soil motion. Based on the modified Winkler model, the finite-depth elastic foundation is equivalent to the additional mass of the nonlinear energy sink system, and the vibration suppression effect and parameter optimization of the elastic foundation on the finite-length beam supported by it under simple harmonic excitation is conducted. The nonlinear dynamic response of a simply supported beam on an elastic foundation is analyzed using the Galerkin method, the incremental harmonic balance method, and the arc-length continuation method. Furthermore, on the basis of verifying the correctness of the theoretical results by numerical methods, through multi-parameter optimization and analysis, the suppression effect of limited range soil on the dynamic response of its supporting beam is revealed, and the optimal parameter range of nonlinear stiffness and damping of the elastic foundation is proved. The results show that by adjusting the elastic soil parameters to the optimal range by technical means, the amplitude reduction percentage of the finite-length beam can reach more than 96%, and it has a wide vibration suppression frequency band.

In order to solve the problem of input ground motion of fault-crossing structure and reveal its seismic response law, based on the physical model of the fault and the equivalent pulse function, this paper constructs a matrix considering the spatial variation characteristics of ground motion. A hybrid simulation method of high and low frequency superposition is proposed to simulate the input ground motion on both sides of the fault. Firstly, based on the established bridge site fault model, the stochastic finite-fault method is used to generate high-frequency ground motion at the target location. Secondly, according to the characteristics of pulse effect and permanent displacement of ground motion on both sides of the strike-slip fault, different equivalent pulse models are used to simulate the parallel and normal low-frequency pulse components of the fault respectively. The Butterworth filter is used for high-pass and low-pass filtering at the cut-off frequency. According to the drilling data, site model and the spatial coherence of ground motion on both sides of the strike-slip fault, a transformation matrix is established to simulate its spatial variability. Finally, the high and low frequency components after matched filtering are superimposed in time domain to obtain the input ground motion on both sides of the fault. The rationality of results is examined in three aspects including time history, response spectrum and structural response. 3D dynamic finite-element model of the actual fault-crossing suspension bridge is established using OpenSees to analyze the seismic response under the simulated ground motions. The results show that the angle and position of the fault-crossing and the amplitude of the permanent displacement have a significant influence on the seismic response of the fault-crossing bridge. The large residual internal force and residual displacement are the important reasons for the damage of the bridge.

To identify an efficient and accurate feature selection algorithm for filtering seismic intensity indicators, the performance of four common feature selection algorithms, MIC, ReliefF, XGBoost and Lasso, was compared and analyzed. Based on the incremental dynamic analysis results of single-degree-of-freedom structures and the ground motion features, the feature selection regression model was established, the ground motion features was sorted and screened according to the Euclidean distance, the performance of the feature selection algorithm was evaluated according to the screening results, and the least squares regression model was established based on the incremental dynamic analysis results of the 2-storey, 4-storey, 8-storey and 12-storey reinforced concrete frame structures, and the standard deviation change of residual was used to measure the prediction ability of ground motion intensity measure selected by different feature selection algorithms for structural collapse. The results show that the accuracy of the ground motion features screened by the Lasso regression algorithm is 31% higher than that of other algorithms when used for structural collapse prediction. The results can be used as a feature selection algorithm reference for the selection of ground motion intensity measures in the uncertainty analysis of ground motion in the structural vulnerability analysis under the performance-based earthquake engineering (PBEE) framework, and can also be used as an effective feature selection algorithm reference for the selection of ground motion intensity measure s suitable for structural collapse prediction.

There is a significant difference between the spatial distribution of ground motion along cross-fault regional areas (Ground motion in the area of the extreme proximity to the fault where the cross-fault engineering structures are located, referred to as cross-fault ground motion) and near-site ground motion. The lack of records on cross-fault ground motion poses challenges to studying the seismic resistance of cross-fault structures. This paper aims to outline the basic theory of the broadband hybrid method for simulating ground motion, and examines the distribution pattern of cross-fault ground motion using the Zemu River fault as a case study. The results indicate that the simulated cross-fault ground motion aligns with the fault sliding mode, displaying significant directional, up-disk effect, and slip-impact effect. Generally, the intensity of the simulated cross-fault ground motion follows a certain attenuation law. However, it is influenced by fault rupture, which can result in irregularities or even a counter-law phenomenon. Furthermore, the actual location of surface rupture and the zone of large slip along the fault have a substantial impact on the distribution pattern of cross-fault ground motion. By employing the broadband hybrid method, artificial cross-fault ground vibration time series can be generated to address the lack of recorded cross-fault ground motion. This methodology provides substantial support for research on the seismic resistance of cross-fault structures.

To study the comfort level of human-induced vibration of a variable section steel-truss pedestrian bridge and the vibration reduction effect of tuned mass damper (TMD), a steel truss girder pedestrian bridge on the Beijing Hangzhou Grand Canal was taken as the research object. Finite element simulation and on-site measurement were used to study the human-induced vibration response of the steel truss pedestrian bridge. Based on the finite element model, the vibration response of the bridge before installation of TMD was analyzed, the pedestrian comfort level was determined, and the influence of pedestrian density, damping ratio and crowd excitation frequency on the bridge was discussed. In this way, the TMD design parameters were given, and the influence of TMD mass ratio on the vibration reduction effect was analyzed. On site measurements were conducted on the pedestrian bridge after the installation of TMD, and based on which acceleration time history and frequency spectrum analysis were used to study the human-induced vibration response of the bridge under corresponding operating conditions. Comparison of the results shows that before installing the TMD, the acceleration response of the bridge exceeds the specification limit, and the effect of human-induced vibration should be considered. In a certain range, the acceleration response increases with the increase of pedestrian density and decreases with the increase of damping ratio. The vibration response increases significantly when the pedestrian step frequency is close to a certain order of the vibration frequency of the bridge. After the installation of TMD, the measured human-induced vibration response of the bridge is reduced, and its response is consistent with the simulation results. The research results in this paper can provide theoretical support for the study of human-induced vibration of variable section steel truss bridge.

For the large yield displacement of the buckling-restrained steel plate wall(BRW), only stiffness and bearing capacity can be provided in the small deformation stage. BRW can not dissipate energy in the small deformation stage. To solve this problem, the wall type friction damper (FD) and buckling-restrained steel plate wall are arranged in parallel in the thickness direction to form a new type of buckling-restrained steel plate wall combined with friction damper (FD-BRW). In the small deformation stage, the friction damper in the composite member slides to dissipate energy. As the deformation increases, the buckling-restrained steel plate wall yields, and the friction damper and the buckling-restrained steel plate wall dissipate energy together. Based on the test results of BRW, FD and FD-BRW, a simplified calculation model was established to simulate the mechanical properties of FD-BRW. The simplified calculation model consists of three springs. The calculation results of the simplified model were basically consistent with the experimental results, which can replace the solid finite element analysis and can be directly applied in the overall analysis of the structure. Based on the simplified model, taking the optimal additional damping as the control index, the reasonable ratio of the sliding friction force of friction damper to the yield bearing capacity of the buckling-restrained steel plate wall (slip-yield ratio) and the recommended value of the height-width ratio of the member were discussed through parametric analysis. The results showed that the height-width ratio is recommended to be less than 1.5, and the reasonable range of slip-yield ratio is 0.07~0.10.

By reviewing literature in the field of earthquake engineering, the pulse-component models of earthquake ground motions are collected and organized. The characteristics of various pulse models are compared and discussed. The research significance of these pulse-component models is concluded and organized to form a systematic research framework. According to the existing research results, it is pointed out that the seismic hazard analysis considering the pulse effects in earthquake ground motions is the core in the research framework. Although the pulse models use different mathematical expressions to describe the same pulse characteristics, their performance is similar in structural dynamics. There are similarities between the pulse models with the forward directivity effect and those with the fling-step effect. At last, the details on considering the pulse effects in ground-motion selections for seismic design of structures are discussed.

To investigate the vibration comfort level of reinforced truss composite slabs applied in residential building floors, the vibration response of the integral connection reinforced truss composite slabs under human-induced excitation loads was studied through experiments. Three types of loading excitations, including single-person walking, three-person asynchronous walking, and three-person synchronous walking, were designed for experiments. For the single-person walking load experiment, three different walking paths including longitudinal, transverse, and diagonal were designed. The vibration response of the composite slabs under various human-induced excitations and walking paths was investigated. A refined finite element model of the composite slabs was established to analyze the influence of the protective layer thickness at the plate bottom, truss height, density ratio and modulus ratio of concrete to reinforcement on the natural frequency of vibration of the composite slabs. The results show that the peak acceleration under human-induced excitation increases with the layer height. The peak accelerations under different human-induced loading conditions decrease in the following order: three-person synchronous walking, three-person asynchronous walking, and single-person walking, and the peak acceleration under single-person walking condition is independent of the walking path. The natural frequency of the composite slabs decreases with the increase of the thickness of the protective layer at the plate bottom, and reaches the maximum when the truss height is 80 mm. The natural frequency is inversely proportional to the concrete-to-reinforcement density ratio, and is directly proportional to the concrete-to-reinforcement modulus ratio.