To study the impact of floor slab construction on metro-induced vibration responses and to explore the feasibility of reducing structural responses by optimizing floor construction, the conventional floor slab, the thickened floor slab and the additional sub-beam floor slab were designed and manufactured. Field model tests were carried out on the three test floor slabs respectively to study their dynamic response under on-site metro vibrations. Taking conventional floor slab as the test control group, the effects of increasing floor slab thickness or adding sub-beam on the floor slabs' characteristics and metro-induced vibration responses were compared and analyzed. The results indicate that the resonance effect is the main reason of metro-induced vibration responses of the floor slab. Increasing the floor slab thickness or adding sub-beam increases the vertical modal frequency of the floor slab, alleviate the resonance effect, and reduced the time-domain acceleration responses of the floor slab. Both increasing floor slab thickness and adding sub-beam can reduce the vibration acceleration level of the floor slab in a wide frequency band, and can reduce the weighted vibration level by 6 dB and 4 dB respectively, thus improving the vibration comfort performance of the floor slab. Adding secondary beams achieves a vibration reduction effect similar to doubling the floor slab thickness without significantly increasing the floor slab's weight and engineering cost. It is recommended that the addition of sub-beams as a floor construction measure be priority in the design of new metro adjacent structures to mitigate metro-induced vibration responses and improve vibration comfort.

This study focuses on two aftershocks of magnitude 5.0 or above in the Haicheng earthquake of 1975, and explores in depth the directional characteristics of their ground motion and the relationship with the seismogenic fault. The response directional characteristics of several types of structures were analyzed using structural measurement point records. First, the background of the Haicheng earthquake is explained, subsequently based on analysis methods such as omnidirectional response spectrum, duration spectrum, and input energy spectrum, the vibration records of six observation stations in Haicheng and Yingkou were analyzed in detail. The results show that the variation of ground motion intensity in different directions is significant, especially when the period is between 1.5~3.5 seconds. The directional effect of seismic intensity of Haicheng aftershocks is more significant than that of the SB14 model of NGA-West2. The directional effect of long-period (≥1.0 s) is particularly prominent, and in the long-period frequency band, the directional difference of near fault ground motion is more pronounced. In the high-frequency range of the omnidirectional response spectrum, there is a high correlation between the east-west dominant direction and the F2 east-west hidden fault, while the mid low frequency range clearly shows the directional characteristics of the F1 north northwest main fault. The directionality of structural reactions may undergo some changes due to structural factors, such as structural form, major and minor axes, site conditions, etc. The seismic response directionality of bridge piers is basically consistent with the free field directionality, while there is a certain degree of rotation in the directional response of building structures.

To study the longitudinal seismic response and damage state of the high-speed railway track-isolation bridge system, a 7-span 32 m simply supported beam bridge with CRTSⅢ type ballastless track structure laid on the bridge deck was taken as the research object. A finite element model of the track-bridge system was established, and the seismic response distribution law of each key component under different seismic waves, seismic intensity and bearing types was obtained through nonlinear time-history analysis. The results show that the longitudinal displacement of the beam body presents a stepwise distribution under longitudinal seismic excitation, with the maximum value occurring at the center of the bridge span. The maximum displacement of the fastener occurs at the expansion joint of the abutment, and extreme values appear at the expansion joint at each beam end. The displacement of the fastener is significantly affected by the spectral characteristics of different seismic waves. The maximum stress of the rail occurs at the expansion joints on both sides of the side span, and the normal stress of the composite slab section is caused by the combined action of axial force and bending moment components. After the bearing and track system enter the nonlinear state, compared with the increase in seismic intensity, the increase in longitudinal deformation of the vulnerable components shows a significant amplification effect and distribution imbalance. Considering the track system, compared with the friction pendulum bearing, the same ball direction double spherical surface bearing can significantly reduce the displacement response of the fastener, beam body and bearing. The track system has a significant inhibitory effect on the displacement of the bearing.

The laminated rubber bearings of in-service bridges are prone to aging, which leads to the time-varying mechanical properties of the rubber bearings, resulting in changes in the structural response under earthquakes action. To explore the time-varying laws of the mechanical properties of in-service laminated rubber bearings, this paper employed the accelerated thermal aging method to age eight laminated rubber bearings for different times. The variation laws of the horizontal force-displacement hysteresis curves, horizontal shear stiffness, and friction coefficients of laminated rubber bearings under different aging times under compression-shear action are discussed. The finite element model of a three-span prestressed concrete diagonal continuous beam bridge is established, and the influence of the stiffness and friction coefficient of the aging laminated rubber bearings on the seismic response of the upper and lower structures of the bridge under different seismic intensities was analyzed. The results show that aging has a significant impact on the mechanical properties of laminated rubber bearings, causing the horizontal force-displacement hysteresis loops of the bearings to become larger. Moreover, with the increase in aging time, the horizontal shear stiffness and friction coefficient of the bearings increase. The time-varying nature of the mechanical properties of aged laminated rubber bearings can reduce the rotational displacement of the superstructure girder of the skew bridge, but it leads to an increase in the seismic forces of the substructure and increases the risk of damage to the substructure. Therefore, the aging of laminated rubber bearings cannot be ignored, and the aging degree of laminated rubber bearings needs to be quantified when evaluating the seismic performance of in-service bridges.

Ground motion has significant uncertainty, and different ground motion response spectra under the same amplitude have significant differences, which have a significant impact on the estimation of seismic damage to regional buildings. This study developed a regional building seismic damage simulation program suitable for multiple-story masonry and concrete frame structures, which can conveniently and quickly simulate regional buildings seismic damage under set earthquakes, and performed regional building damage simulations and probabilistic analysis with motion uncertainties. A typical urban region in Chifeng city was selected as the research area: 30 ground motions were selected to consider their uncertainty, and the ground motions amplitudes were modulated to the set intensity (0.05 g, 0.10 g, 0.20 g, and 0.40 g). Then seismic damage simulation of regional buildings under single and multiple seismic inputs were conducted respectively, the impact of seismic uncertainty on the seismic damage results of regional buildings was analyzed. Based on the seismic damage results under the set intensities, a probability density distribution model of regional buildings damage index based on Beta distribution was established. Results indicate that multiple seismic inputs take into account the uncertainty of seismic motion, which can more scientifically and objectively reflect the seismic damage situation of regional buildings; The established Beta distribution model can be used to estimate the post-earthquake damage of buildings in similar areas. The research results can provide reference for regional buildings safety assessment and seismic fortification.

To address the issue of brittle failure induced by welding residual stress and inherent buckling failure of thin steel plates in conventional shear panel dampers (SPD), this paper proposes a novel prefabricated angle steel-constrained shear panel damper (PASPD). The structural configuration, operational mechanism, and distinctive features of the PASPD are comprehensively elucidated. Two prototype specimens were designed and manufactured for experimental investigation. Quasi-static low-cycle reversed loading tests were performed to evaluate the hysteretic behavior, energy dissipation capacity, and failure characteristics of the PASPD. Experimental results demonstrate that the PASPD exhibits stable hysteretic performance and superior energy dissipation characteristics. The study reveals that increasing the web plate thickness can delay the initiation of corner cracks but does not alter the fundamental failure mode of the PASPD. Appropriate boundary constraints using angle steel significantly regulate the stress and strain distribution within the PASPD, concentrating the deformation and energy dissipation in the central region. Compared with the traditional steel plate shear dampers, PASPD exhibits superior ductility performance and higher cumulative energy dissipation. The finite element simulation analysis demonstrates that the synergy between the flange connection plate and the side angle steel can optimize the shear force transmission path of the PASPD, guide the stress and strain distribution of its web to be more uniform, and form an ideal web shear energy dissipation mechanism, thereby enhancing the stability and hysteretic energy dissipation performance of PASPD.

Ground motion prediction models are an important foundation for seismic hazard analysis. Currently, the research on vertical ground motion prediction models in China is relatively few, and most of the existing ground motion prediction models used parametric equations, which may have limited prediction accuracy. Therefore, the development of horizontal and vertical ground motion prediction models with better prediction accuracy and reliability is necessary for further research. To address the above problems, this study, uses 1991 sets of Chinese horizontal and vertical ground motion records. The Butterworth non-causal filter method is applied to filter and reduce the noise of Chinese ground motion. The Chinese horizontal and vertical ground motion prediction model (CHV-DNN) is developed based on the deep learning method, and it is comprehensively assessed in terms of model performance, physical characteristics, and intra-and inter-event residual analyses. Finally, a correlation coefficient model for Chinese horizontal and vertical ground motion is provided. The results show that based on the residual analysis results of the CHV-DNN model, the most of the inter-event residuals are mainly distributed in the range of [-1, 1], and most of the residuals within events are mainly distributed in the range of [-1.5, 1.5], and the intra-event and inter-event residuals are both uniformly distributed on both sides of the residuals 0 baseline, which validate the reliability and accuracy of the model; The CHV-DNN model has better prediction accuracy and also has well physical characteristics; the correlation coefficient model calculated based on CHV-DNN has been more reasonable. The Chinese horizontal and vertical ground motion prediction model developed in this study will provide a research foundation for horizontal and vertical seismic hazard analysis in China.

Corner concrete damage and failure in shear wall structures under seismic loading is one of the primary factors leading to degradation of overall structural performance. This study focuses on steel-concrete modular prefabricated composite shear walls, proposing four optimized corner design schemes: curved steel thick-plate (CSTP) design, stiffened CSTP design, folded steel thick-plate (FSTP) design, and stiffened FSTP design. The seismic performance of these optimized designs was compared with that of non-optimized composite shear walls, followed by an investigation into the parameter influence patterns of the optimal design. Results demonstrate that all four corner optimization schemes enhance the seismic performance of modular prefabricated composite shear wall specimens, with the stiffened FSTP design showing the most significant improvement. This optimal design substantially improves the collaborative working capacity of the structure, increasing initial stiffness, peak bearing capacity, cumulative hysteretic energy dissipation, and ultimate drift angle by 40%, 43%, 44.7%, and 23.58%, respectively, compared to the non-optimized scheme. Optimal parameter ranges for the stiffened FSTP design are provided, offering references for practical engineering applications.

The Great East Japan Earthquake on March 11, 2011, triggered a massive tsunami that caused devastating destruction to buildings in coastal cities. However, in areas unaffected by the tsunami, buildings experienced relatively fewer collapses or severe damage, despite the high seismic intensity. This study explores the characteristics and impacts of seismic damage from this earthquake, reveals the intrinsic relationship between ground motion features and building damage, and analyzes the seismic damage data and spatial distribution of building clusters using a vulnerability model established based on the 1995 Great Hanshin Earthquake. Through the analysis of building collapse rate, we found that the computed results closely aligned with the actual seismic damage survey outcomes. The analysis indicates that seismic damage was concentrated in coastal areas such as Miyagi, Fukushima, and Ibaraki Prefectures, particularly in narrow inland zones near the coastline. Notably, the areas most severely affected were not always the closest to the epicenter or the zones with the highest intensity. Furthermore, significant differences in collapse rates were observed across different building codes, with buildings constructed under newer regulations showing a markedly lower collapse rate compared to those built under older standards. This research contributes to a better understanding of the seismic damage characteristics associated with offshore earthquakes, providing crucial insights for earthquake defense and disaster relief efforts.

Mountain terrain of significantly alters the propagation path and energy distribution characteristics of seismic waves. Through interactions such as reflection, scattering, and diffraction, the seismic response of local sites exhibits notable spatial variability. This terrain effect has a significant impact on the seismic response of engineering structures in mountainous areas and is one of the key factors contributing to the intensification of earthquake damage. To consider the impact of terrain effects on ground motion parameters in engineering seismic design, this study uses a railway station building site as the example. A three-dimensional finite element model of the mountain area where the station building is located was established. A viscoelastic artificial boundary is set for the model, and historical seismic data recorded by observation stations in the region were used as the ground motion input. The seismic response of the mountain region was obtained, and a comparative analysis of the input seismic motion and response results was performed to analyze the impact of the mountain height difference on the terrain amplification effect. The results show that at higher elevations (such as the freight yard and station building locations), the amplification effect is significant, while at lower elevations, the amplification effect is weaker, displaying a characteristic distribution along the height difference from large to small. The highest elevation of the site is more sensitive to high-frequency (10~20 Hz) seismic motion components. The peak ground acceleration is significantly positively correlated with the height difference, indicating that the height difference of the mountain terrain is a key factor influencing the site amplification effect. The study concludes that the terrain amplification effect is closely related to the height difference and topographical variations in mountainous areas, providing important theoretical guidance for the seismic design of major engineering projects in mountainous regions.