The investigation of earthquake damage shows that the lateral spread of gently inclined soil is a common form of foundation failure. As the concrete pile has a high vertical bearing capacity and shear resistance, and the stone column has a high permeability, which can effectively reduce the degree of liquefaction of the surrounding soil, whether the concrete-stone composite pile can be used as an effective engineering measure to deal with the large lateral deformation of liquefaction in gently inclined soil, its feasibility is worthy of in-depth research. Therefore, the numerical model of liquefiable soil-pile foundation is established based on OpenSees finite element platform, then the reliability of the numerical model is rerified. On this basis, the reinforcement effect of concrete-stone composite pile on inclined liquefaction soil is studied. In addition, the effects of area ratio of core pile and thickness of stone shell on dynamic response of inclined liquefaction soil are discussed. The results show that the concrete-stone composite pile has a significant anti lateral displacement effect, which can effectively reduce the lateral displacement of the surrounding soil and the bending moment of the concrete core pile. When the proportion of concrete core of pile body is about 20% and the proportion of stone shell area is 80%, it is the optimal design scheme.

Many steel-concrete composite curved box girder bridges have been built recently, while in these bridge designs, the understanding of vehicle-bridge coupled vibration was limited. Due to the effect of bending-torsion coupled under vertical loading, the change of the reaction force of the relevant support bearing has not been well solved. In this paper, based on the ABAQUS general finite element software, the horizontal curved motion of the vehicle was simulated by the method of Fourier series, which made the numerical analysis of vehicle bridge coupled vibration be possible. The numerical analysis results had verified for its accuracy with the existing experimental and theoretical ones. Taking a steel-concrete composite box girder bridge with four spans as an example, further analysis were carried out considering the influence of the support bearing force of bridge under the case of vehicle on the inside and outside lanes and superelevation . The results indicate that the outer support bearing of the other side of the box girder will appear falling, when the vehicle is driving along the inside or outside lanes of the curved girder bridge. The vehicle speed has little influence on the peak support bearing force, while the bearing separation can be alleviated by the lower vehicle speed. The superelevation has little effect on the support bearing reaction force. When the vehicle is driving along the inside lane, it will be easy to alleviate the falling of some support bearings of the outside box girder. When it is driving along the outside lane, it will aggravate the bearing separation of the inside box girder.

Shaking table test is an effective means to study the complex dynamic characteristics and seismic response of large structures, and it is the key to desigh the scale model structure in the shaking table test due to the limitation of shaker size and load. Based on the dimensional similarity method and elastic similarity law, the geometric similarity ratio of 1∶20 was taken, and the design of the dynamic scale model of key parameters was carried out using a spatial special-shaped arch bridge as the prototype. Firstly, through finite element numerical analysis, the dynamic characteristics, internal forces and displacements of the original bridge model and the scaled bridge model under dynamic action are analyzed to verify the rationality of the scaled model. Under the selection of reasonable seismic action, the structural time history response analysis was carried out. The calculation results show that the scaled model bridge is completely consistent with the first tenth-order mode of the prototype bridge with the frequency error less than 7%, the response error of internal force, displacement and acceleration of the key section has not exceeded 10%, and the scaled model bridge can reflect the dynamic characteristics and response characteristics of the original bridge. This research work can provide technical support for the seismic design of shaking table of space irregular arch bridge, and provide reference for shaking table tests of similar bridges.

The mass concrete used in gravity dam is easy to lead to inhomogeneity of strength due to its inherent characteristics, construction quality and other reasons. In the current seismic analysis of concrete dams, concrete is generally regarded as a material with uniform strength distribution, but there are few studies on the influence of strength inhomogeneity on dam dynamic damage. Based on the plastic damage theory of concrete and the probability distribution model of Weibull, Python language is used to redevelop ABAQUS. On the premise of considering the plastic damage of concrete, the influence of random inhomogeneity distribution of concrete strength on the damage of gravity dam body and bedrock is studied. The dynamic damage of dam and bedrock, the interaction between dam and reservoir water, and the radiation damping of infinite foundation are comprehensively considered in calculation. The dynamic responses of dam and bedrock after earthquakes, such as damage area distribution, damage area ratio and damage dissipation energy, are compared and analyzed. The influences of inhomogeneity concrete strength on dam and bedrock seismic damage are revealed. The research results can provide reference for the design and construction of gravity dam.

On Dec. 18th, 2023, a magnitude 6.2 earthquake hit Jishishan Town of Linxia City in Gansu Province, and caused an unusual mud sliding disaster in Jintian Village and Caotan Village of Zhongchuan Town in Qinghai Province. The mud flowslide resulted in catastrophic consequences as casualties and demolishing and burying of residential houses. Such large mud sliding phenomenon has not been frequently reported in historical earthquakes. Through field investigation, it is confirmed that the underlain soil liquefied and triggered the disastrous phenomenon which has already been termed liquefaction-induced flowslide. Nevertheless, the massive liquefaction-induced flowslide is the first time been reported and verified by field evidence in recent 70 years. The investigation and analytical results demonstrate that the underlain soil layer in the upstream area liquefied, triggering instability and catastrophic flowslide, and the soil and water conditions in the flowing channel potentially accelerated the sliding. It is deduced that liquefaction possibly occurred in many a place, that is, the sliding channel was suspected of liquefying in various spots. The ground shaking intensity in the sliding area maintained relatively high, and that the peak ground-motion acceleration was estimated around 0.4 (±0.1) g. The findings and investigation results are useful to help understanding the mechanism and process of the uncommon flowslide disaster.

In order to realize the safety protection of floating cultural relics during earthquakes, a nonlinear quasi-zero stiffness isolation system is analyzed. The stiffness model and the motion balance equation of the isolation system were established, and the harmonic balance method and Newton iterative method were used for theoretical analysis, and the fourth-order R-K method was used for numerical analysis of the motion balance equation under harmonic excitation and ground motion excitation. The theoretical analysis results show that the nonlinear quasi zero stiffness of cultural relics of the isolation system under harmonic excitation, outer excitation frequency is low frequency phase, the response of the system is unstable region, therefore, if the rigidity and damping ratio of the system is improved the unstable area and peak amplitude response of the system will be reduced, and make it tend to be characteristic of the linear vibration isolation system. Increasing the damping ratio can reduce the effective initial frequency of the isolation system, but increasing the damping ratio in the effective frequency band will increase the transfer coefficient of the system. Increasing the spring stiffness will increase the effective initial frequency of the isolation system, but reduce the amplitude response of the system in the low frequency stage, but increase the transfer coefficient of the system in the effective frequency band of the isolation system. Numerical analysis shows that there are only two stable solutions in the unstable region, and the response state of the system is related to the initial state of the system. The system can significantly reduce the acceleration response of input ground motion under the action of actual ground motion excitation. The damping coefficient of the isolation system is insensitive to the change of the input peak value of the ground motion with less long period components, but is sensitive to the change of the input peak value of the ground motion with more long period components, indicating that the isolation performance of the system is better for the short period ground motion, which is consistent with the theoretical analysis results under the action of simple harmonic excitation.

A recoverable precast shear wall composed of precast RC wall and steel energy-dissipator (RPSW-SE) was proposed and tested under reversed cyclic load. The failure process, shear capacity, hysteretic behavior and degradation characteristics were compared with that for cast-in-place concrete shear wall. Moreover, the damaged specimens were repaired by replacing damage steel member and tested again to investigate the seismic performance including hysteretic behavior, shear resistance as well as energy dissipation capacity, and to discuss the recoverable of RPSW-SE. The results showed that the RPSW-SE had good integrity and shear resistance, and the hysteretic curves were relatively full. The steel-energy connection area yielded prior to RC wall and dissipated a large amount of energy, enhancing the deformation capacity and energy dissipation capacity. The stress distribution and damage evolution of the shear wall was improved, and the failure of the RPSW-SE was caused by the fracture of the short steel-column at the slits of the shear-plate, without obvious plastic damage in the concrete wall. It was analyzed that more than 90% of the energy-dissipation in the shear wall was concentrated in the steel-energy connection area, achieving the controllable damage and energy dissipation. The performance indexes of the repaired RPSW-SE were close to those of original ones, indicating that the RPSW-SE had good recoverability.

After thousands of years, the Archery Tower of the Deshengmen has been damaged in different degrees and types. Through the investigation of the damages, the number, proportion and distribution of the damage types have been summarized and the causes of the typical damage characteristics and its influence on the mechanical performance of the wooden frame have been analyzed. In order to explore the influence of the typical damage characteristics on the mechanical behavior, the comparative analysis on the influence of pulling-out of tenon on the mechanical behavior of the wooden frame is made, and the FEM of the standard frame and the frame in the state of pulling-out of tenon are established. Results show that the damages are mainly concentrated in the column frame layer and the beam frame layer. The damage of the column frame layer is mainly manifested by cracking and inclination. The typical damage of beam frame layer mainly includes pulling-out of the tenon and horizontal crack of wooden beam. Besides, the moment-rotation angle curve of joint has obvious asymmetry. The failure state of the joint is the tearing failure of the cross grain at the variable section of the tenon. When the amount of pulling-out of the tenon is numerical, the amount of pulling-out of the tenon has no obvious effect on the flexural bearing capacity of the frame. When the amount of pulling-out of the tenon increases to a certain level, the flexural bearing capacity of the beam frame will decrease significantly, and the positive peak bearing capacity will decrease significantly relative to the negative loading. The positive decrease rate is 16% ~ 18%, and the negative decrease rate is 9%~15%. The study results can provide important references for the safety protection and repair of traditional wooden structures.

With the increase of concrete age and performance degradation, the dynamic response of concrete dam will change significantly. The heightened gravity dam is also affected by the difference between new and old concrete materials. In order to study the influence of the aging of gravity dam materials and the performance difference of new and old concrete in heightened gravity dams, taking the heightened Danjiangkou gravity dam as an example, the seismic dynamic response analysis is carried out by using the ABAQUS finite element analysis software. The demolition and reconstruction (the new material condition) and the construction according to the heightened height (the old material condition) are compared with the heightened condition, analyzing the responses of heightened gravity dams to the displacement of the crest, the stress at key points, and the plastic damage with the aging of the concrete material properties under seismic dynamics. The results show that with the increase of the aging degree of concrete materials, the dynamic response of the heightened gravity dam is generally better than that of the old materials and inferior to the new materials. The damage of the dam body tends to extend downward to the joint surface of the new and old concrete. The heightened gravity dam has the characteristics of strong adaptability, low damage index and high anti-sliding stability coefficient, which improve the comprehensive characteristics of the dam body. Besides, the weak parts such as the new and old joint surfaces should be reinforced and bonded to give full play to the engineering benefits of heightening the gravity dam.

To investigate the seismic performance of the monolithic precast concrete wall with concealed steel plate bracing, a two-story monolithic precast concrete wall with concealed steel plate bracing and a benchmark two-story cast-in-situ wall with the same bracing were designed and constructed. The bracings in the precast wall were connected by welded joints at the wall-to-wall and wall-to-foundation connections to fit the larger construction tolerance. Cyclic loading tests were conducted on the walls. The results indicated that the bracings in the precast wall connected by welded joints were able to satisfy the large construction tolerance requirement and transfer the internal force well. The seismic performance of the monolithic precast concrete wall was emulative to the cast-in-situ wall in terms of the lateral strength, stiffness degradation, and energy dissipation. Both of the walls were failed in flexure, but the monolithic precast wall formed an additional plastic zone at the top interface of the post-casting segment.