To realize the resilience of structure under earthquake and solve the problem of large residual deformation of energy dissipation dampers, a prefabricated self-centering energy dissipation brace assembled with U-shaped steel plates and pre-compressive disc springs (U-SCEB) has been developed. This innovative brace comprises a pre-compressive disc spring self-centering system and a U-shaped steel plate energy dissipation system, assembled in parallel. Compared to previous self-centering energy dissipation braces with combined disc springs, the U-SCEB has better deformation capacity and can be fully assembled on-site, facilitating the replacement of damaged U-plates after an earthquake. The configuration and working principle of the U-SCEB were described, and its restoring force model was established. The self-centering capability of the combined disc springs and the energy dissipation capability of the U-shaped steel plates were investigated by the quasi-static cyclic loading test, and the hysteretic behavior of the U-SCEB was further studied by the quasi-static loading test. Finally, the finite element model of the brace was established, and the influence of different design parameters on the hysteretic performance of the U-SCEB was analyzed. The results show that the configuration of the brace is simple, and the self-centering principle is clear. The brace can be assembled on-site, and the components are replaceable. The restoring force model of the brace presents a typical flag shape. Under the quasi-static cyclic loading, damage to the brace is mainly manifested as plastic damage at the connection between the flat and bent sections of the U-shaped steel plate, and the hysteresis curve exhibits stable energy dissipation, excellent self-centering ability, and significant deformation capacity. To ensure the excellent self-centering capacity of the brace, the pre-compressive force of the disc springs should be larger than or equal to the peak strength of the U-shaped steel plates.

Aiming at the problem of secondary impact caused by mismatching parameters of traditional isolation system with displacement restrictor, firstly, a mechanical model of the quasi-zero stiffness (MMPDQZS) isolation system was established by using the opposed disc spring as the negative stiffness component and the repulsive permanent magnets was used to adjust the nonlinear positive stiffness. The static characteristics of the system were analyzed. Then, the mathematical model of MMPDQZS isolation system was established. The influence law of different damping parameters on the impact isolation performance of MMPDQZS isolation system was analyzed. The impact characteristics were compared and analyzed through simulation and experimental study for without and with equivalent linear displacement restrictors and MMPDQZS limiters. The results show that for any initial clearance, there is an optimal viscous damping ratio that minimizes the system’s buffer coefficient. Smaller initial clearances generally lead to better impact isolation effects. Considering different initial clearance, the damping ratio of power-law fluid damping is 0.02, the velocity correlation index obtains the optimal buffer coefficient within the interval [2.2, 2.3], and the optimal initial clearance is when the clearance is equal to 4 mm. For any initial clearance, the buffer coefficient is proportional to coulomb damping, and smaller initial clearances result in better buffering performance. Compared with the equivalent linear limit isolation system, MMPDQZS limit isolation system can not only effectively limit the relative displacement, but also greatly reduce the buffer coefficient of the system and improve its impact resistance.

The combined seismic isolation bearing is composed of a sliding friction bearing and an elastomeric bearing. The bearing system offers a substantial vertical support capacity, various post-yield stiffness choices, and the ability to separate the bridge’s vertical support system from the horizontal support system. To investigate the seismic performance of the combined seismic isolation bearing system, by way of example of a continuous beam bridge with each continuous unit of (4 × 40) m spans, the OpenSees software was used to model with the conventional spherical steel bearing, full sliding friction bearing and combined seismic isolation bearing support systems to obtain the longitudinal seismic response of the bridges, respectively. The influence of seismic parameters such as sliding friction coefficient and shear stiffness on the seismic performance of the combined seismic isolation bearing was discussed. The results demonstrated that the combined seismic isolation bearing exhibits excellent seismic performance and self-centering ability. The seismic performance of the combined isolation bearing will be affected by the sliding friction coefficient and shear stiffness. By selecting appropriate seismic parameters, the maximum displacement demand of bearings, the residual displacement of bearings, and the seismic response of the piers can be effectively controlled.

A structural system for energy dissipation and shock absorption with displacement amplification damping walls across multiple stories is presented. According to structural characteristics of the cable-bracing displacement amplification damping wall, the deformation and force characteristics of the device were analyzed, and presented theoretical formulations for the cable-type damping wall system’s damping force and energy dissipation. The simplified numerical model was established, the parameters that affect the structural performance indicators were analyzed in detail, the fixed-point theory was used to design the optimal parameters of the cable-type damping system, and the energy-dissipating deformation magnification equation was derived to quantify the degree of damping efficiency. A 30-story concrete frame core tube was analyzed for the seismic time-history analysis, though the vibration absorption efficiency of the three damping wall layout schemes of displacement amplification damping wall installed in single story and cable-bracing displacement amplification damping wall system installed in multi-story were compared, it is found that the cable-bracing displacement amplification damping wall system installed in multi-story has a better shock-absorption effect.

To analyze the seismic response of different forms of long-span arch bridge-track systems, four different forms of arch bridges, namely 112 m basket handle arch bridge, 140 m steel box tied arch bridge, (24+160+24) m tied arch bridge and (52+382+52) m steel box arch bridge, are used as examples. The study revealed the dynamic characteristics of long-span arch bridge-track systems under seismic action and explored the effects of seismic waves, seismic intensity, and traveling wave speed on the seismic response. The results show that the stress envelope of the rail under seismic uniform excitation is antisymmetrically distributed, with the maximum value appearing near the end of the beam and the maximum axial force of the arch rib at the arch foot. There are large differences in the dynamic characteristics of the system under different spectral characteristics of seismic wave excitation. The change in seismic intensity mainly affects the rail stress near the end of the beam, and has less effect on the middle beam section. The traveling wave effect has a significant impact on the seismic response, with a significant increase in the axial force of the arch rib. The maximum stress in the rail increases by 149.2% compared to the seismic uniform excitation, and the longitudinal force in the rail at the middle of the span increases significantly, up to 503.4 MPa. Furthermore, the stress in the rail is greater when the apparent wave speed is smaller. Similarily, the stress on the rail increases as the traveling wave speed decreases. As the traveling wave speed increases, the stress distribution on the rail gradually approaches that of consistent excitation.

At present, the research of asphalt concrete core dam under near-fault ground motion is mostly carried out under the condition of single SV and P wave oblique incidence. In fact, the assumption of single wave oblique incidence is not comprehensive, and the near-fault ground motion should be considered as the case of combined P wave and SV wave oblique incidence. In this paper, the oblique incidence time history of SV wave and P wave in the site was determined based on ground motion inversion, and the deformation and damage of the core wall dam were obtained under the oblique incidence of SV and P wave combination near the fault, and the change law of the damage of the dam body with the horizontal and vertical ground motion intensity index was analyzed. The results show that the ultimate failure probability caused by the vertical near-fault ground motion index is obviously different from that caused by the horizontal direction. When the horizontal ground motion intensity indicators near the fault are selected as S_a(T₁)₁, S_v(T₁)₁, VSI₁ and S_d(T₁)₁, and the vertical ground motion intensity indicators are selected as PGA₂, S_a(T₁)₂, VSI₂ and S_d(T₁)₂, the predicted failure probability of the dam body is moderate. The combined damage analysis method of horizontal and vertical ground motion should be considered when analyzing the vulnerability of core wall dam under near-fault ground motion.

To upgrade the level of rural housing to meet the increasing demand for comfort, safety, environmental protection and energy saving, a light frame structure system housing was proposed and designed. The light frame structure system takes a steel frame as the main structural body and ALC wall panel as the filling wall. A full-scale shaking table test has been carried out to verify its seismic performance and to study the seismic behavior and seismic response law of the light frame structure system under earthquake action on beam-column joints, wall-slab joints, and the building structure. The test results show that the wall panel has not fallen off, the joint connection is intact, and the structure has not collapsed. With the increase of input seismic intensity, both the acceleration amplification factor and relative displacement increase, while the natural frequency of the structure decreases gradually. Throughout the test, the main structural members remain elastic, and the inter-story displacement angle of the structure under a fortification earthquake of 6-degree is less than 1/250. Under the action of rare earthquakes of 7th intensity and 8th intensity, the inter-story displacement angle of the structure exceeds 1/250, but the structural deformation can be reduced by tensioning reinforcement support. The light frame structure system exhibited excellent seismic performance and can be used to improve the level of rural housing in the 6th intensity seismic fortification area. For seismic fortification areas above 6th intensity, the seismic performance can be enhanced by increasing the tension of tie bars.

The electromagnetic performance of phased array antenna is greatly affected by the phased array antenna surface deformation. How to apply the strain measurement data of sparse fiber grating strain sensors to sense the shape of antenna array is the key to realize structural health monitoring and electromagnetic performance control. This paper proposes a virtual sensing method for structural deformation under complex experimental modes. In this method，the complex mode transformation is first used to process the complex mode data obtained from modal testing to obtain the corresponding real displacement modes，and then the full field expansion of finite real displacement modes is realized using mode expansion；Combining the extended real displacement modal and finite element modal data，two virtual sensing equations named CMT-SEREP（complex mode transformation-system equivalent reduction expansion process）and CMT-LC（complex mode transformation-local correspondence），which characterize the relationship between sparse measured strain information and the full field displacement of the structure，have been derived to achieve the real-time estimation of the deformation shape of the antenna structure from sparse measured strain information. Using the developed large phased array antenna array deformation experimental platform，experimental verification of different sensing methods was carried out under three deformation working conditions. Experimental results show that the proposed method can reconstruct the full field displacement of the antenna array structure using sparse strain measurement information，and the sensing accuracy of CMT-LC is higher than that of CMT-SEREP. Compared to the traditional modal method，the relative percentage error of deformation sensing using CMT-LC method has been reduced by at least 6.105%. This method is not only suitable for deformation sensing of non-proportional damping antenna structures，but also suitable for other complex engineering structures，and it has a great application potential.

Time-varying modal identification is important to obtain the dynamic characteristics of time-varying engineering structures and realize real-time vibration control and online health monitoring of structural systems. Aiming at the problems of measuring the excitation of engineering structures and low efficiency of time-varying modal identification，an output-only recursive identification method based on dynamic mode decomposition（DMD）is proposed in this paper. To extend the theory of the existing DMD method，this paper draws on the projection approximation subspace tracking algorithm and the sliding-window idea，and proposes a recursive format of the DMD method，which can update the system matrix and the proper orthogonal decomposition basis recursively，and can be further used for the output-only recursive modal identification of time-varying systems. A numerical example of a three-degree-of-freedom structural system with time-varying mass and an experimental setup of a liquid-filled cylindrical structural system with variable mass are respectively designed and built to validate the proposed method numerically and experimentally. The results demonstrate that the proposed recursive DMD method is able to accurately identify the modal parameters of the time-varying structures by only using the measured vibration response data，and has good output-only recursive identification capability.

An axisymmetric finite element-boundary element coupled computational method is proposed for the dynamics of cylindrical shells with endplates in water. Due to the periodic characteristics of the structure，the movement of the cylindrical shell and end plate can be determined by examining their meridional movement，and the meridians are discretized into several elements for further analysis. By using the energy method，the elemental matrices are obtained and assembled into the global matrices. Then the discrete schemes for structural motion with the finite element is established. Considering the axisymmetric characteristic of the fluid，an axisymmetric boundary element on the meridians is established and the calculation format for fluid-elastic forces on the finite elements is given. The fluid forces are then converted into an equivalent nodal force at the nodes and the effects of the fluid are evaluated by the added mass，damping，and stiffness matrices. By combining the structural motion and the schemes of fluid-elastic forces，an axisymmetric finite element-boundary element coupling method is developed to solve this fluid-structure coupling problem. The calculated results presented in this paper demonstrate good agreement with existing theoretical solutions and commercial analysis software，validating the accuracy of present method. Moreover，this method exhibits higher computational efficiency compared to commercial analysis software. It allows for direct determination of the mass and stiffness matrices of cylindrical shells in fluid，facilitating fast calculation of forced vibration. Based on this method，the wet frequencies and stability characteristics of complex cylindrical shells with end plates in axial flow are analyzed. The results show that the end plates will change the flow velocities on the cylindrical shell and make it more easily to instability.