In order to obtain more accurate and refined dynamic characteristics of the flat boom tower crane，the field test of the dynamic response of the typical freestanding flat boom tower crane was carried out considering the influence of lifting positions，lifting heights （rope lengths） and lifting weights. The test results show that the vibration along the boom axial direction and vertical direction has good synchronization. However，the response correlation between the horizontal direction of the vertical boom and the axial and vertical direction of the tower crane boom is relatively low. The natural frequencies identified by the half-power bandwidth method and the SSI-COV method are basically the same，with the difference of lifting positions，rope lengths and lifting weights，the natural frequencies of flat boom tower crane will fluctuate around the natural frequency under no load. There are some differences in the identification results of the damping ratio between the two methods，in most working conditions，the damping ratio identified by the SSI-COV method is smaller than that identified by the half power bandwidth method. Based on orthogonal test analysis，the influence of the above factors on the natural frequency and damping ratio of the tower crane is not significant，and there is no main effect. In addition，the finite element model of the flat arm tower crane is optimized，and the frequency of the updated model is in good agreement with the test results. The boom vibration mode function under no-load condition was fitted，the amplitude distribution along the boom length exhibits an approximately linear，however，when the lifting weight appears at the end or root of the boom，the boom vibration mode may show an obvious nonliner characteristics.

Existing bridges undergo time-varying load effects and resistance degradation during service. The complex loads and diverse failure modes make the existing bridges face greater risks in service. Therefore，it is urgent to make time-dependent reliability assessment for the service bridges. The classical time-varying reliability analysis method is more complex and difficult as the number of random variables increases. In this paper，probability density evolution theory is introduced to solve the above problem，which is more advantageous for solving the reliability of complex structures with multiple random variables. The dynamic reliability of the existing bridge in serviceability limit state and ultimate limit state is analyzed by considering the bridge resistance degradation and load effect increase，as well as the time-varying factors such as shrinkage and creep effect of concrete bridges. The accuracy and computational efficiency for this method are compared with the Monte Carlo method，and the effectiveness of the proposed method is verified.

Post-tensioned prestress，self-centering brace and shape memory alloy （SMA） are the main ways to realize the self-centering of the structures. However，the construction of post-tensioned prestress is complex，the concentrated force generated by self-centering brace may cause joint damage，and the SMA is expensive. The disc springs are preloaded to provide the self-centering force. A self-centering rebar splice is developed to connect the longitudinal rebars in the reinforced concrete structures. The calculation method of the stiffness，preload and effective stroke of the self-centering rebar splice is established. Four rebar splices with different preload force，stiffness and effective stroke are designed and manufactured，and the mechanical properties of the rebar splices are tested. The parameters of the rebar splice adopting the Bouc-Wen model are identified based on particle swarm optimization algorithm. The results show that the self-centering rebar splice has a stable half-flag hysteretic curve and excellent self-centering performance. The Bouc-Wen model can accurately describe the hysteretic characteristics of the rebar splice，and the fitting data are in good agreement with the test data.

Focusing on a type of cable-bracing inerter system that utilizes positive and negative teeth ball screws to achieve self-balancing properties，this paper explores the prospect of its application in high-rise or super high-rise structures with complex deformation characteristics of bending and shearing. This paper develops a simplified model for the dynamic analysis of bending-shear structures based on the modified Timoshenko beam theory in order to take into account the accuracy and computational efficiency of the simulation of the original structural dynamic characteristics. Three types of cable layout schemes are proposed for the cable-bracing-self-balancing inerter system，and the appropriate cable layouts for the structures with different bending-shear deformation ratios are verified. A quantitative metric is proposed to optimize the anchorage position for structure-specific modal control. The accuracy of the optimization results is confirmed in the time and frequency domains through the application of fixed-point theory for single-modal control. The following conclusions can be derived. The higher the percentage of bending deformation of the structure is，the more effective the vertical connection of the cables will be，and the more effective the diagonal connection will be as the percentage of shear deformation increases. With regard to structure-specific modal control，the optimized anchorage position and fixed-point theory methods can significantly increase the damping efficiency of the inerter system.

In order to achieve rapid construction and reliable connection of precast RC frames，a sleeve-type fully-bolted joint is proposed. The ends of the prefabricated components are reinforced with a steel sleeve-concrete combination. High-strength bolts are pre-built in the sleeve area，and the precast components are rapidly installed using a connection plate. A total of four test specimens were designed for different thicknesses of connecting cover plates. The horizontal hysteresis test study obtained the damage mode，load-displacement hysteresis curve，ultimate bearing capacity，ductility and energy dissipation capacity of this type of joint. The results show that the new joint has a 43% higher ultimate load，70% higher initial stiffness and nearly 50% higher ductility than the cast-in-place joint，and the equivalent viscous damping coefficient is increased by about two times，which shows better seismic performance. Strain analysis reveals that the cover plate at the joints shows a “stress increase”，but the effect on the overall performance is not apparent. As the thickness of the connection plate increases，the squeezing effect of the sleeve on the concrete increases. Therefore，a connection stiffness ratio of 1.6 is more reasonable. Finally，based on the test results，a trifold moment-turning angle model is established，and the calculated results agree with the test values.

In practice，earthquakes typically involve a mainshock followed by a series of aftershocks，and their occurrence is highly unpredictable. The mainshock damages the structure，and the aftershocks worsen the response and damage of the structure. However，no studies have investigated the effects of stochastic seismic sequences on AP1000 nuclear power plants. This paper proposes an analytical framework for studying the dynamic response and reliability of AP1000 nuclear power plants under stochastic main aftershocks. Stochastic main aftershock sequences are generated using the physical stochastic function model of ground motions，narrow-band harmonic group superposition method，and Copula function. The dynamic response of the AP1000 nuclear power plant is analyzed by using ABAQUS software. The direct probability integration method （DPIM） is used to obtain the probability density function of the maximum displacement response in the horizontal direction of the shielded building，and its dynamic reliability is calculated. The results show that the acceleration and relative displacement of the top of the shielded building and the steel containment vessel have increased to varying degrees after the aftershock，compared with experiencing the mainshock only. Additionally，the damage area between the water tanks and the vents has expanded. The aftershocks could cause further damage to the nuclear power plant. The dynamic response of nuclear power plants exhibits a high degree of randomness due to the stochastic ground motions. Aftershocks can reduce the reliability of nuclear power plants to varying degrees under different thresholds.

According to certain selection criteria，this paper selects 8 mainshock-aftershock events and 560 mainshock-aftershock sequences from NGA-West2 ground motion database，uses ASK14 ground motion prediction equation to carry out residual analysis on the mainshock-aftershock sequences，obtains the intra event residual of mainshock-aftershock sequences at each station，and standardizes them. According to the geostatistical semivariogram method，the exponential semivariogram model and the manual fitting method are used to calculate the spatial autocorrelation of the spectral acceleration period of the mainshock-aftershock sequence. Since the Pearson linear correlation coefficient can better measure the linear relationship between the fixed-distance variables，the Pearson linear correlation coefficient is used to calculate the cross-correlation of the normalized intra-event residuals between different spectral acceleration periods of the mainshock-aftershock sequence without considering the spatial cross-correlation. According to Markov’s hypothesis，the spatial information is introduced into the calculation of the cross-correlation，and then the expression of the change of the spatial cross-correlation with the spatial distance （h） is obtained. The results show that the mainshock is significantly different from aftershocks in terms of spatial autocorrelation and cross-correlation characteristics，and aftershocks generally have higher spatial correlation in the long-period stage. Neglecting the spatial correlation between the mainshock and aftershocks or using the characteristics of the mainshock to replace the characteristics of the aftershocks will adversely affect the research on earthquake hazard analysis，damage assessment，and the synthesis of main and aftershock sequences.

Compared with the in-plane seismic performance，the out-of-plane seismic performance of reinforced concrete shear walls is weak and usually neglected，which leads to an inadequate study of the out-of-plane damage mechanism of shear walls and a lack of clear protective measures，and the overall seismic performance of shear wall structure is also unsafe，which needs urgent attention. In order to compare the similarities and differences in seismic performance of reinforced concrete shear walls when subjected to in-plane and out-plane loads in different directions and to clarify the key influencing factors，low cyclic loading tests are conducted on typical shear wall specimens in-plane and out-plane directions，and the macroscopic test phenomena，hysteresis curves，skeleton curves，stiffness degradation curves，energy dissipation capacity and ductility in both directions are compared and analyzed. The moment-curvature simulations of shear wall sections in both in-plane and out-plane directions are analyzed，and the results obtained from multiple sets of constitutive models are compared with the experimental results. Combined with the finite element variable parameter analysis，the effects of parameters such as axial pressure ratio，wall thickness，height-to-width ratio and concrete grade on the seismic performance of in-plane and out-plane are analyzed. Based on the endurance time analysis，the time-history response of structural displacement with seismic magnitude is studied. The results show that the seismic performance of shear walls outside the face is significantly weaker than that inside the face，and the bearing capacity is only 1/20~1/15 times of the latter，among which the wall thickness and height-width ratio are the main parameters affecting the seismic performance inside and outside the face. The out-of-plane nonlinear analysis of the cross-section can be performed more accurately and quickly by using the principal structure model proposed in this paper and some traditional principal structures. In the seismic design of shear walls，especially for the single directional wall with less structure，both in-plane and out-of-plane seismic performance should be ensured，and the thickness and aspect ratio of shear walls should be reasonably controlled. Wall damage assessment by using elastic-plastic energy dissipation difference rate has the characteristics of obvious differentiation and reasonable threshold value.

Based on the Biot’s poroelastic model and the Euler-Bernoulli beam equations，the dynamic response of extended helical pile foundations with multiple helixes is studied. The equivalent stiffness model is used to simulate the helixes on the helical pile. With the utilization of the integral transform，the variable separation methods，and the impedance matrix transfer method，the analytical solution to the dynamic response of helical piles with multiple helixes is derived. Through the comparisons with the simplified analytical solutions and the experimental results，the correctness of the proposed model is justified. Finally，with the presentation of a comprehensive parametric study，some dominant impact factors on the dynamic responses are revealed，and the optimal design scheme is suggested accordingly. The main conclusion of this study can be concluded as：An increase of the extension ratio of helix will increase the complex impedance and resonance frequency at the pile top of the helical pile. An increase of the ratio of helix spacing to width will increase the complex impedance of the pile top，but the effect on the resonance frequency is not significant. An increase of the vertical static load at the top of the pile will significantly reduce the complex impedance and resonance frequency at the pile top. The helix inclination has an optimal range in the effect of complex impedance of the pile top.

The principle of the hydraulic drifter is introduced，and the process of drilling into rocks by the drifter is established as a physical model of rock with three-degree-of-freedom dry friction. The concept of rate of penetration （ROP） is introduced. The stick and non-stick modes are studied，explaining the differences between these two types of motion. The periodic trajectories of the nonlinear piecewise smooth dynamical system mathematical model are segmented. By using the pseudo-arclength continuation method and Floquet theory，the angular frequency and amplitude of the hydraulic force are taken as control parameters to obtain stable periodic trajectories and the point of maximum ROP. Bifurcations such as period-doubling bifurcation，saddle-node bifurcation，and torus bifurcation are discovered. The data acquisition system for drilling rocks with a hydraulic drifter is introduced，and the displacement and velocity of the piston obtained from the model and experiments are compared. The results indicate that to make the drifter work on the period-1 trajectory，the range of angular frequency should be ω<6.814，and the range of amplitude should be 0.03<a<3.051. There is a strong correlation between the experiments and the model，and compared with the experiment，the piston in the model undergoes deceleration before colliding with the drill tool，adding an impact deceleration stroke.