In order to test the micro-vibration control ability of the mass concrete slab in the Beijing High Energy Photo Source, evaluation of the micro-vibration control ability of the mass concrete slab are conducted through two short-period tests and a 24 h long-period monitoring. Test results indicate that: most of the displacement root mean square values distribute between 10 nm and 50 nm in the two short-period tests, and most of the displacement root mean square values distribute below 20 nm in the 24 h long-period monitoring. The mass concrete slab can provide good micro vibration control performance over 10 Hz for the micro vibration in the vertical direction, and over 5 Hz for the micro vibration in the horizontal directions. Through casting the mass concrete slab, the micro vibration level in the vertical direction can be reduced by 24%, the micro vibration level in the horizontal direction can be reduced by 34%. The control ability of the slab to the horizontal micro-vibration is slightly better than that of vertical micro-vibration. Moreover, simplified two-dimensional finite element models are established to discuss the influence of changing the concrete layer’s density, stiffness and thickness on the slab’s micro-vibration control ability. The simulation results indicate that the increasing thickness of reinforced concrete layer or density of the plain concrete layer has no influence on the micro-vibration control ability of slab in the vertical direction, but has adverse effect on that in the horizontal direction.

The specimen-table interaction effects can significantly affect the accuracy of shaking table acceleration time history. Iterative control is often an important means to improve the reliability of test data. However, masonry, reinforced concrete and other structures are prone to enter the nonlinear mechanical state due to cracking, which is often not suitable for iterative loading. A simulation study is carried out on the iterative control method of the shaking table based on the surrogate specimen model. First, a surrogate specimen model with similar dynamic characteristics to the specimen was constructed, after completing the iterative loading of the shaking table and obtaining the driving command with the surrogate specimen model, a real specimen-shaking table test was carried out. The simulation results show that the shaking table iterative control based on the surrogate specimen model effectively reduces the influence of the specimen-table interaction on the system control performance, and realizes the high precision reproduction of the acceleration time history of the table.

The seismic damage investigation and analysis were performed on buildings in Moxi Town and Detuo Town in the meizoseismal area of the M_s6.8 Luding earthquake in Sichuan. Buildings with the characteristics of looseness, brittleness, and eccentricity were seriously damaged, while buildings with confined masonry structure and “even” structural layout have performed surprisingly well. Based on deformation saturation theory and the damage of Luding earthquake, the structural layouts of common buildings were divided into five forms: structure with full hard-brittle axis, structure with full weak-brittle axis, structure with full weak-ductility axis, structure with hard-brittle axis and weak-ductility axis ( either uneven or even), and the corresponding seismic damage performance and internal mechanism of each form were analyzed. The results indicated that the structure with full hard-brittle axis, the structure with full weak-brittle axis and the even structure with hard-brittle axis and weak-ductility axis had not reached the deformation saturation, so the seismic damage was extremely light, with almost no visible cracks, while the buildings with other structural layouts were damaged or even collapsed. Finally, it is suggested that the seismic design of structures should have the concept of “even” by using deformation saturation theory.

The influence of frequency content in earthquake wave on the torsional response of the single-story symmetric frame structure is studied in this paper. The dynamic equilibrium equation for the single-story symmetric frame structure subjected to earthquake wave passage excitation is given, and the relative motion method is adopted to solve the equation. The time-domain analytical solutions in series form to earthquake wave passage excitation are given for torsional responses. The peak column shears of the frame to wave passage excitation are respectively calculated for earthquake waves with sufficient and insufficient frequency content, and the influence of the frequency content on wave passage effect is analyzed. Studies show that the analytical solutions of column shears to wave passage excitation are not only related to the natural frequency and excitation frequency, but also related to the time delay and the square of the ratio of structural fundamental frequency to excitation frequency. The earthquake wave passage effect of frame structure is prone to occur for those earthquake waves whose main frequencies of earthquake acceleration amplitude spectra are lower than the structural fundamental frequency. There is not earthquake wave passage effect for those earthquake waves whose main frequencies are higher than the structural fundamental frequency. The earthquake wave passage effect of frame structure depends not only on the time delay, but also on the low-frequency content. The joint action of low-frequency content and time delay can produce the earthquake wave passage effect. The richer the low-frequency content, the more obvious wave passage effect.

The 6.2 magnitude earthquake in Jishishan of Linxia Hui Autonomous Prefecture in Gansu Province occurred on December 18, 2023. The earthquake caused extensive damage and collapse of town and village buildings, resulting many casualties. It is a typical small earthquake and large disaster. This paper summarizes the seismic damage characteristics and patterns of typical village and town buildings surveyed in the epicenter of the Jishishan earthquake, and analyzes typical cases based on the structural type, construction year, and whether seismic measures are used. The reasons for the severe seismic damage in this earthquake are summarized as follows: Some self-build houses have brick columns and adobe walls, but the two parts are lack of effective connections and have poor seismic resistance. This can be seen from the fact that houses with ring beams and structural columns in the same courtyard are basically intact, but houses without seismic structural measures are severely damaged. Some have varying openings on different floors, resulting in discontinuous vertical force transmission. There are many irregular planar arrangements in the structure. Partial structures are incomplete or have weak areas. Rural self-build houses are constructed according to the habits of craftsmen, without considering the stress requirements under earthquake actions, and a quality supervision system mechanism needs to be established.

Based on the seismic damage data of Wenchuan earthquake, the seismic vulnerability model of entirety and different sections of mountainous tunnel is obtained by regression analysis. The peak ground acceleration (PGA) was selected as the ground motion parameter and the lognormal distribution was selected as the vulnerability model, and the seismic vulnerability curves of the tunnel structure of entirety and different sections (entrance shallow burial section, entrance transition section, ordinary section, fractured section) were obtained by the maximum likelihood estimation, and the vulnerability characteristics of different section and the whole tunnel were compared and analyzed. Under the condition of slight damage, the seismic vulnerability of the entrance shallow burial section is higher than that of other section. With the increase of the degree of damage, the seismic vulnerability of the fractured section is gradually higher than that of other sections of the tunnel. The average loss rate model of the tunnel was established by combining the loss ratio of tunnel structure in a specific failure state. The tunnel vulnerability models and average loss ratio model established in this paper can be used to evaluate the seismic loss rapidly in the event of similar earthquakes in the future.

Passive variable damping and stiffness device is a device that does not require external energy input and feedback control, and has the functions of variable damping energy consumption and variable stiffness limit. By combined with isolation bearings, this device forms a new isolation system that can effectively control seismic waves of different types and intensities. Based on the theory of performance-based design, a design method for composite isolation systems has been proposed. Through this method, the parameter design of passive variable damping and stiffness devices and isolation bearings in the isolation layer can be completed. The study also provided a complete design process and detailed explanation of the design process, and verified the feasibility and effectiveness of the design method through engineering examples. This performance design method can be widely applied in the engineering design field of composite isolation new systems, providing a reliable design method and technical support for related engineering. Through this advanced design method, the structure can better cope with disasters caused by earthquakes, ensuring the safety and stability of the structure.

The seismic damage of rural dwellings in the M_s 6.2 earthquake in Jishishan is explored. The structural characteristics, construction habits and construction techniques of the rural dwellings in the disaster area were summarized. The collapse and typical earthquake damage characteristics of rural dwellings with different structural forms were analyzed. The mechanisms of traditional building practices on the seismic resistance and disaster prevention capability of residential houses were studied. The results of the research and analysis show that the structural systems of rural dwellings are mostly “tiger hugging head” style brick-wood structure, accounting for 50.9% of the total number of researched houses, and there are fewer cases of earthen structure and brick-concrete structure, accounting for 28.2% and 20.9%, respectively. There are many cases of the overall collapse of the earthen structure in the study area, fewer cases of overall collapse of brick-wood structure, and no cases of total collapse of brick-concrete structures. The earthquake damage of brick-wood dwellings mainly consists of cracking at the corners of the gable walls, dislodging at the joints, partial collapse of the gable walls, and cracking of roof laps. The main earthquake damage to earthen dwellings is damage to the corner of the gable wall, collapse of the gable wall, and collapse of the roof. Earthquake damage to brick-concrete structure mainly consists of wall cracking, wall collapse and floor (roof) damage. Bad construction habits such as mud joints, thick-covered loess roofs, and large-weight door decorations exacerbated the earthquake damage to residential houses and should be improved in the subsequent restoration and reconstruction work. Measures and suggestions to improve the earthquake-resistant and disaster-preventive capacity of rural dwellings were put forward with regard to the seismic damage characteristics of different structural systems and construction habits, with a view to providing reference for the construction，strengthening and renovation of rural dwellings in the disaster areas.

In order to explore the influence of the parameter changes of piles on the near-field active vibration isolation after the concrete row piles were installed in the foundation, a three-dimensional finite element model consistent with the test site was established in the finite element software, and the finite element model was verified by calculation and analysis. The calculation results were verified and full-size finite element model was established with reference to the TB 10621—2014 Code for design of high-speed railway, and the specific influence of the parameter changes of row piles on the vibration isolation effect under the action of the train load was analyzed. The analysis results show that the effect of the pile length parameter on the vibration isolation effect is obvious. As the parameter increases, the vibration isolation effect is more ideal. When the pile length parameter is 10.5, the ratio will continue to increase, and the vibration isolation effect will not improve significantly. The larger the parameter is, the less ideal the vibration isolation effect is, and the smaller pile spacing can achieve the ideal vibration isolation effect. The burial depth parameter has a significant impact on the vibration isolation effect, the larger the parameter, the less ideal the vibration isolation effect. When the parameter is 3.5, the vibration isolation effect will be unsatisfactory, and a shallower burial depth can obtain a better vibration isolation effect.

In addition to the direct incident body wave at the bottom, the sub-basin in the basin and sub-basin also have laterally propagated surface waves generated by the large basin, which lead to the change of the resonance characteristics of the sub-basins. Based on the explicit finite element method, the effects of sub-basin impedance ratio, large-basin dip angle and half-width on the resonance frequency and amplification factor of two-dimensional trapezoidal basin and sub-basin under the vertical incidence of SH and SV waves are comparatively analyzed. The results show that: affected by the laterally propagating surface waves generated in the large basin, the maximum values of PGV and E_x in the sub-basin are obviously amplified, and the amplification of SV waves is greater than that of SH waves. The sub-basin impedance ratio has a great influence on the maximum PGV, E_x, resonance frequency and amplification factor of the basin and sub-basin, while the dip angle and half-width of the large basin have little effect. Compared with a single small basin, the resonance frequency of the sub-basin increases under the incidence of SV wave and SH wave, with the value of incidence of SV wave greater than that of SH wave under the same impedance ratio. The amplification factor of the sub-basin under the incidence of SH wave is basically larger than that of the single small basin, while the SV wave is lower than the single small basin under the low impedance ratio, but higher than the single small basin and the SH wave incidence under the high impedance ratio. The resonance frequency and amplification factor of the basin and sub-basin are more affected under the incident SV wave than that of SH wave.