Based on the actual damage and the mechanical characteristics of the component, a dumbbell-shaped component is proposed by dividing the wall units along the midline of the span. To verify the phenomenon of internal force and deformation concentration during the loading process of dumbbell-shaped components, quasi-static tests of rectangular and dumbbell-shaped components with equal initial stiffness were designed. Wall shear strains and relative displacements at different positions were tested. The analysis results show that the dumbbell-shaped components undergo shear failure first, with damage concentrated between windows, causing the floor to collapse vertically along the side of the dumbbell-shaped component. Shear strains on the cross-section of dumbbell-shaped components are significantly higher than those of rectangular components, and the strain ratio gradually increases with displacement. Relative displacements on the upper and lower sides of the wall between windows indicate that as the loading displacement increases, the ratio of the upper wall to the wall between windows gradually decreases, while the displacement ratio between the wall between windows and the lower wall gradually increases. Both strain and displacement indicate that during the deformation process, internal forces and deformations gradually concentrate towards the wall between windows. Based on the analysis results, the collapse mechanisms of masonry structures and masonry-frame hybrid structures are discussed.

This paper proposes a nonlinear spring restraint structure to overcome the limitations of the static thrust test method in evaluating underground structure systems. Considering the difficulties of soil-structure interaction, high costs, and limited observability of test phenomena, the proposed approach integrates basic principle of the reaction displacement method for underground structures. It recognizes that the traditional elastic spring fails to capture soil state changes during loading, thus prompting the introduction of a more dynamic spring-structure system. It suggests using nonlinear springs instead of soils for analyzing seismic performance. Through Pushover analysis on a single-span underground structure model, the influence of factors such as the axial compression ratio and spring-structure interaction on mechanical performance is investigated. Comparing bending moment capacity curves of key sections shows that the static thrust overlay model for spring-underground structures is suitable for seismic analysis of underground structures. Up to an inter-story displacement angle of 1/200, both the linear and nonlinear spring models are highly accurate, but beyond this threshold, the nonlinear spring model is significantly superior. The simplified analysis method for seismic performance of nonlinear spring-underground structure systems provides insights into the complex force behaviors of underground structures.

To characterize the mechanical properties of 7075 high-strength aluminum alloy, three specimens for the monotonic tensile test and five specimens for cyclic loading were designed and fabricated. Based on the Ramberg-Osgood model, numerical fitting was carried out separately for the monotonic tensile stress-strain curves and cyclic loading skeleton curves of aluminum alloy bars. A comparative analysis was conducted on the tensile mechanical properties and hysteresis mechanical properties of 7075 high-strength aluminum alloy. The combined hardening parameters for high-strength aluminum alloy were calibrated, and a combined hardening hysteresis constitutive model was established. Using the software ABAQUS, a numerical analysis model of high-strength aluminum alloy was created, and the simulation results were compared with and validated against experimental results. The results indicate that 7075 high-strength aluminum alloy exhibits excellent hysteresis performance, and the Ramberg-Osgood model shows good applicability to the monotonic mechanical properties of high-strength aluminum alloy. The finite element simulation results based on the combined hardening model are in good agreement with the test results. The calibrated combined hardening model can be used for the seismic behavior analysis of structures reinforced with high-strength aluminum alloy.

The substation is the core link in the transmission and distribution of electricity. Post-electrical equipment holds an important position in substations. They are not only numerous but also diverse, and are very likely to be damage in earthquakes. This paper takes the 500 kV voltage transformer as the research object, installs a new type of steel wire rope seismic isolation bearing on it, and compares and analyzes the response characteristics of the prototype structure and the seismic isolation structure under seismic action through the seismic simulation shaker test. The test results show that the fundamental frequency of the isolation structure has been significantly reduced compared with the prototype structure, confirming the effectiveness of the new wire rope seismic isolation support in reducing the seismic response of post-electrical equipment. Meanwhile, the seismic isolation structure shows high isolation efficiency in reducing acceleration and stress response, but the isolation effect for displacement response is relatively limited. Under strong seismic effects, the seismic isolation structure can effectively reduce the acceleration and stress response of the equipment, which reduces the risk of breakage of porcelain insulators of transformers due to vibration. At the same time, the seismic isolation bearings will not have significantly reduced the top displacement response of the equipment. Therefore, in the subsequent improvement of the new wire rope seismic isolation support, it is necessary to comprehensively consider the various responses caused by seismic forces to ensure the overall safety of the equipment.

The isolation structure is equipped with isolation devices to extend the natural vibration period and reduce the seismic response. However, improper construction causes the infill wall to be built around the isolation device, which restricted the free movement of the superstructure, thus affecting the actual isolation performance of the structure. In order to quantify the impact of the above unfavorable factors on the seismic isolation performance of the structure, this paper takes a certain reinforced concrete(RC) frame as the research object, uses a method of combining in-situ testing and numerical simulation, and compares and analyzes in the OpenSees considering whether the constraint effect of the infill wall is taken into account. Seismic response of isolation structures under different types of earthquake motions. The research results show that compared with unconstrained seismic isolation structure, the maximum acceleration of the upper floors, the maximum inter-story drift and the maximum base shear force of structures with seismic isolation layers constrained by peripheral infill walls increase by 20.4%, 38.7%, 35.7% under frequent earthquakes. The displacement of the isolation layer is reduced by 79.4%. Under the action of seismic precautionary earthquakes, they increase by 21.6%, 59.8%, 86.5%, respectively, and the displacement of the isolation layer is reduced by 37.8%. Under the action of rare earthquakes they increased by 17.7%, 19.4%, and 14.9% respectively, and the displacement of the isolation layer decreased by 10.3%. As the peak acceleration of the input ground motion increases, the lead rubber bearing will play a greater role only after the infill wall is damaged. Under rarely occurred earthquake, the seismic isolation layer breaks through the constraints of the surrounding filling walls and can basically achieve the seismic isolation effect.

In the seismic response analysis of locally irregular sites such as basins under plane wave incidence, it is usually assumed that the input seismic motion is of a single wave type, i.e., SV wave, SH wave, or P wave. However, the actual incident motion is generally a multi-dimensional coupled shaking case. Based on the spectral element method, the ground motion response of a three-dimensional semi-ellipsoidal sedimentary basin under the vertical incidence of plane waves is simulated. By analyzing the distributions of peak ground acceleration (PGA) and the corresponding amplification factor, the seismograms along the surface point profile, and the response spectrum ratio distribution at the characteristic frequencies, the ground motion amplification features of the sedimentary basin under multi-dimensional ground motion input are investigated through comparisons with the results of single wave type incidence. The results show that compared with the unidirectional horizontal seismic excitation, the bidirectional horizontal seismic input has a significant amplification effect on ground motion in the basin, and the maximum amplification factor can reach 1.87. Considering the influence of simultaneous input of bidirectional horizontal ground motion, the distribution characteristics of the peak ground acceleration will change significantly. The superposition and interference of waves propagating in different directions result in an asymmetrical PGA distributions. The bidirectional ground motion input makes the wave propagation characteristics more complex, and the location of the strongest ground shaking changes. In addition to the amplification of the response spectrum value, the bidirectional input also has a certain influence on the distribution of the predominant period.

Vertical ground motion is a serious threat to bridges and other structures in high intensity areas, and the relationship with horizontal ground motion is complicated. However, the current Code for seismic design of railway engineering(GB 50111—2006) (2009 edition) does not make special provisions for the vertical design response spectra. Some other specifications only stipulate that the vertical response spectra should be taken as a fixed ratio of the horizontal spectra, which may make the estimation of vertical ground motion unreliable. In view of the urgent need to revise the current seismic design code for railway engineering in China, 4 350 ground motion records at home and abroad were selected, and a quantitative study on the ratio of vertical to horizontal acceleration spectra according to the site category and magnitude classification was carried out. The results show that the ratio of vertical to horizontal response spectra generally exceeds the fixed value of 0.65 given by the current codes such as Code for seismic design of buildings (GB 50011—2010), and is significantly affected by the site category and seismic intensity. Therefore, it was proposed to introduce vertical site coefficient to characterize the vertical ground motion effect, and the method of calculating the vertical site coefficient, which is applicable to code for seismic design of railway engineering, was determined through the trial calculation and comparison with the relevant provisions of Specifications for seismic design of highway bridges (JTG/T 2231-01—2020). The peak ratios of vertical and horizontal acceleration response spectra under different site categories and seismic defense intensities were calculated, and the proposed values of vertical site coefficients were given. The research findings presented in this paper can serve as a reference for determining the value of vertical acceleration design spectra in seismic design codes for railway engineering.

To investigate the seismic performance of partially encased composite columns-reinforced concrete shear walls (referred to as PEC column-RC shear walls), two different connection types were designed and subjected to low-cycle reversed loading tests. The study focused on their failure processes, hysteretic behavior, energy dissipation capacity, stiffness degradation, and strength degradation. Additionally, finite element models were developed to simulate their behavior, which were validated against the experimental results. The models were also used to analyze the seismic performance of PEC column-RC shear walls under different concrete strength grades and axial compression ratios. The results indicate that PEC column-RC shear walls ultimately experience shear failure, yet they exhibit high ductility and energy dissipation capacity, demonstrating excellent seismic performance. In practical engineering applications, the weak-axis connection method for PEC columns can effectively meet seismic performance requirements. As the concrete strength increases, the load-bearing capacity of PEC column-RC shear walls improves, although the ductility decreases. With an increase in the axial compression ratio, the rate of increase in load-bearing capacity diminishes. It is recommended to keep the axial compression ratio below 0.4 in practical engineering designs.

In view of the special performance requirements of the rocking wall, the rocking wall structure is often trapped in the dilemma of construction technology, rocking range and cost control in engineering application. Based on the concepts of economic benefits, convenient construction, and easy replacement after earthquake, an energy-consuming connection device between the frame and the rocking wall was developed. Additionally, a hinge support with controllable swing of the rocking wall was also designed for the test models. Thus, a new type of reinforced concrete (RC) frame-rocking wall damping structure is proposed by loveraging the structural advantages of the rocking wall structures and the principle of passive control technology. Then, 1/10 scale shaking table tests of six-story RC frame structure and RC frame-rocking damping wall were conducted to verify the effectiveness of the structure. The dynamic characteristics, acceleration response, and displacement response of the test models under different earthquakes were studied by shaking table tests. The failure mode and seismic performance of the test models were also described. The results show that the rocking wall damping system can effectively consume seismic input energy and attenuate structural dynamic response, reducing the maximum peak acceleration and the maximum peak displacement of the structure by 36% and 20.15%, respectively. Moreover, the rocking wall damping structure can also effectively suppress the vibration of the main structure by using the principle of passive damping, improving the lateral deformation mode of the frame structure. Additionally the damage process of the structure is delayed, enhanced the overall seismic capacity of the structure.

Soil dynamic parameters are crucial calculation parameters for the seismic response of soil. However, there is currently insufficient theoretical research on soil dynamic characteristics in Heilongjiang Province. To address this, we analyzed data on the dynamic shear modulus ratio and damping ratio of 286 groups of clay, clayey soil, and sandy soil at different burial depths in the region. We derived the characteristic parameters of each group of soil dynamic parameters and statistically obtained a fitting formula for the variation of these parameters with soil burial depth. Using this formula, we calculated the dynamic shear modulus ratio and damping ratio data of different soil types at different burial depths and verified the rationality of the fitting formula. We established six soil seismic response models using soil types with abundant data and input typical seismic motions in Heilongjiang Province. We calculated the fitting parameters a₁, a₂, E(λ_max), E(M), etc. of the fitting formula and studied the influence of the variability of characteristic parameters on peak ground acceleration, characteristic period, and plateau value of ground response spectrum by scaling the fitting parameters. Results show that with the increase of a₁ and E(λ_max) the damping ratio increases, resulting in a decrease in the site amplification factor F_PGA and an increase in the characteristic period T_g. The increase of a₂ and E(M) will lead to a decrease in the damping ratio, resulting in an increase in F_PGA and a decrease in T_g. The plateau value β has a large variability, fluctuating within a certain range without a definite increasing or decreasing trend. Variability has the greatest impact on F_PGA, followed by its impact on T_g, and then on β. The soil seismic response is the most sensitive to the variability of a₁. As the intensity of the input seismic motion increases, the error increases. Overall, this study provides necessary supplements to the research on soil dynamic parameters in Heilongjiang Province.