The tire deformation traveling wave characteristics vary at different vibration frequencies and speeds，and are influenced by the coupling of landing gear structural vibration，resulting in continuous changes in tire lateral deformation modes. The tire models for previous traditional landing gear shimmy analysis are quasi-static restoring force model，which assumes that the functional relationship between tire lateral force，self-aligning moment and lateral deformation is fixed. Based on the tire stretched string theory，a time delay tire model coupled with landing gear shimmy is established to analyze the dynamic changes in tire lateral deformation modes，and the real-time lateral deformation distribution of the tire and the nonlinear dynamic behavior of the landing gear during shimmy are obtained. The time delay is introduced to calculate the tire deformation traveling wave，and the stability of the landing gear tire coupled shimmy model is studied by the bisection method. The testing methods for the parameters of time delay tire shimmy model is provided. Using the methods presented in this paper，the landing gear shimmy analysis and experimental test of a certain aircraft are conducted. The calculated vibration frequency and shimmy stability region are consistent with the analysis results of traditional tire models and test results.

Helicopter cabin noise negatively impacts cabin environmental comfort and safety. In this paper，non-dominated sorting genetic algorithm Ⅱ is used to solve the electro-acoustic device placement problem of the active control system applied in the cabin. An appropriate spatial discretization of the sound field of the confined space is preformed，and then the electro-acoustic devices placement optimization problem，quantity optimization problem，and secondary source sound intensity optimization problem are further transformed into a combinatorial optimization problem. Taking the minimun value of the sum of the squares of the acoustic pressures at the measurement points as the control objective，the multi-objective optimization algorithm combined with the active control algorithm is adopted to solve the optimal placement of electroacoustic devices in the system. Considering the noise control system’s complexity and feasibility and limited space inside the cabin，the control system’s secondary sound sources and error sensors are selected as a 4-channel configuration. The optimization program is repeated several times independently，and the most frequently occurring positions of electroacoustic devices are counted，based on which computer simulation and experiment are conducted，and the results show that the optimization results can make the noise reduction at the height of the head of the cabin personnel in the sitting position reach up to 24.9 dB，and the global noise reduction reaches 19.4 dB.

Based on the flow simulations through delayed detached-eddy simulation model，the methods of sparsity-promoting dynamic mode decomposition and spectral proper orthogonal decomposition are applied for analysing the mode decomposition on the wake flow. Then combined by the acoustic analogy approach，this study investigates the behaviour of flow and aerodynamic noise generated around tandem seal-vibrissa-shaped cylinder in comparison with the cases of tandem cylinderlike and elliptical bars with the same characteristic length corresponding to the cylinder diameter of 30 mm for a range of Reynolds numbers （Re=6×10⁴~1.2×10⁵）. Results show that the lift fluctuations of the downstream bars are stronger than those of the upstream bars and the downstream bars dominate the aerodynamic noise radiation. The alternative arrangement of the saddle and nodal planes of seal-vibrissa-shaped cylinder introduces three-dimensional flow separations and suppresses the shear layer interactions，improving greatly the flow stability. The structure destroys the regular vortex shedding of Karman vortex street occurring in tandem cylinder wake. The presence of reverse vortex shedding generated by two adjacent saddle surfaces in the flow of tandem seal-vibrissa-shaped cylinder makes the lateral force balanced partially and reduces significantly the lift fluctuations as well as the vortex-induced vibration. The aerodynamic noise generated by the non-constant fluctuating force exerted on the wall surfaces of bars are suppressed effectively. The sound pressure level is reduced at most frequencies. Thereby the tandem seal-vibrissa-shaped cylinder is demonstrated to have a significant noise reduction effect. The experimental measurements verify the accuracy of the aerodynamic noise predictions. The current work would provide a certain scientific research and engineering application value for the aerodynamic noise control on cylinderlike bars.

Since current loudness models are unable to predict loudness under round window stimulation，a loudness model for round window stimulation is proposed in this paper. The loudness model consists of a peripheral auditory model and a data processing back-end. The peripheral auditory model that is able to calculate basilar membrane velocities under free-field acoustic stimulation and round window stimulation and the back-end that transforms basilar membrane velocities into loudness are constructed. The reliability of the peripheral auditory model is verified by comparing the model-predicted results with the experimental data on the outer ear transfer function，middle ear transfer function and stapes velocities under acoustic stimulation，round window stimulation transfer function，frequency selectivity and frequency response of the basilar membrane，and basilar membrane displacement. The reliability of the loudness model is verified by comparing the model-predicted results with the experimental data on equal-loudness contours，bandwidth noise loudness，loudness level of tone with frequency masking，and threshold for complex tones. The results indicate that the loudness model accurately calculates basilar membrane velocities under acoustic stimulation and round window stimulation，and is able to predict the loudness of pure tone，complex tones，and bandwidth noise under acoustic stimulation and round window stimulation.

The vibration reduction characteristic of rotor system with active elastic support dry friction damper is studied in this paper. The dynamic model of rotor system is established and a 2D friction model of contact surface in dry friction damper us built. The transient and steady state dynamic responses of rotor system are obtained after dynamic equations being solved by utilizing Newmark-HHT numerical integration method. The steady state vibration signals of dry friction damper rotor system under different normal load are compared，meanwhile the transient dynamic responses of rotor system before and after turning on dry friction damper are studied. Experimental test rig for rotor system and dry friction damper are set up. The vibration signals of rotor while passing the first-second critical speed regions are measured and analyzed. Then the experimental vibration signals are compared with simulation vibration responses to verify the vibration reduction effect，and the vibration attenuation characteristic of dry friction damper on rotor system under different working conditions is studied. The results show that the active elastic support dry friction damper could only attenuate rotor’s vibration within a certain normal force. Finally，the results could provide theoretical guide for vibration control strategy on rotor system.

A magnetorheological elastomer （MRE） vibration absorber is designed to suppress the vibration of industrial robotic milling in order to solve the low frequency chatter problem. The magnetorheological effect of MRE with different mass ratio is studied by using the unique rheological characteristics of MRE. The number of turns of coil and the current in the absorber are determined by theoretical calculation and numerical simulation. It is found that the designed MRE absorber has frequency shift characteristics in the range of 17.35~45.21 Hz through modal simulation and shaking table sweeping excitation experiment. The mapping relationship between natural frequency of absorber and current is established，which is verified by experiments in the milling process of KUKA KR500 robot. The results show that the robot is prone to chatter at its low order natural frequency under low rotational speed machining conditions，and the chatter suppression of the robot is realized by MRE absorber. Compared with the condition without vibration absorber，the peak-to-peak value of the vibration acceleration in the X direction of the robot spindle is reduced by 70.7%，and the root-mean-square value is reduced by 64.7% after being electrified. The peak-to-peak value in the Y direction is decreased by 54.7%，and the root-mean-square value is decreased by 49.9%. In addition，the machining surface quality of workpieces after milling has also been significantly improved.

In order to improve the dynamic output performance and environmental adaptability of the tri-stable piezoelectric energy harvester （TPEH），a new flexible tri-stable piezoelectric energy harvester （FTPEH） with double flexible auxiliary beams for real-time adjusting the potential well depth and barrier height is proposed. Based on the traditional magnetic coupling tri-stable piezoelectric energy harvester，two auxiliary flexible beams with the same structure and size are introduced，and the two external magnets are fixed at the tip ends of the two auxiliary flexible beams. When the harvester is excited by the external excitation，the two auxiliary beams oscillate with slight amplitude in the horizontal direction，thus the horizontal distance between the external magnets and the tip magnet of the piezoelectric cantilever beam can be adjusted in real-time，so as to tune the potential energy well depth and barrier height，resulting in improving the dynamic output performance and environmental adaptability. The electromechanical coupling dynamic model describing the dynamic responses of the new tri-stable piezoelectric energy harvester is established based on Euler Bernoulli theory and Hamilton principle，and the influences of system parameters on the nonlinear magnetic force and dynamic performance are simulated and analyzed. Compared to the traditional tri-stable harvester，the new tri-stable harvester has a wider bandwidth of inter-well motion and lower excitation for jumping from intra-well motion to inter-well motion.

The harmonic vibration produced by the gear meshing in the helicopter’s main reducer is one of the main sources of noise in the helicopter cabin. Designing vibration-isolating gearbox struts to suppress vibration transmission to the airframe can effectively reduce cabin noise. The piezoelectric stack actuators periodic strut （PSAPS），composed of periodically arranged piezoelectric stacks and metallic materials，demonstrates ‘mechanical filtering’ characteristics within specific frequency bands，serving as a passive vibration control method. By adjusting the driving voltage of piezoelectric stacks in PSAPS to achieve variable stiffness characteristics，active vibration control is enabled. In order to study the electromechanical coupling relationship between active vibration control and passive vibration control of PSAPSs，a specialized PSAPS configuration is developed to address helicopter gear meshing noise suppression，and the electromechanical coupling dynamic model of PSAPSs with the form of transfer matrix is established for the mechanical filtering characteristics of periodic structure and elastic wave propagation in piezoelectric stack. In frequency domain，the force and velocity at both ends of the PSAPSs，the driving voltage and current，the geometrical parameters of the strut and the material parameters are coupled in this model. In this paper，the maximum attenuation rate of the PSAPS can be obtained under the limitation of the maximum driving voltage and current of the piezoelectric stack by using this model. The influence of rubber damping loss factor，excitation force，and cell number in PSAPS on the required driving voltage and current for active control is analyzed in this article.

Existing S-transform-based load spectrum editing methods for automotive components suffer from the problem of lack of adaptivity in time-frequency resolution，which affects the time-frequency aggregation of load spectrum energy and leads to poor editing results. To solve this problem，based on the theory of generalised S-transform （GST），the application of GST method in the field of automobile components load spectrum editing is explored. The GST method is used to perform time-frequency analysis of the mount load spectrum to obtain the distribution information of the load energy on the time and frequency axes. The accumulative power spectral density （APSD） of the load spectrum is calculated，and a genetic algorithm is used to determine the threshold value of the APSD in order to identify the time segments of the load spectrum with smaller damage contributions. The time segments of the load spectrum with small damage contributions are identified and removed，and the remaining load time segments are spliced to obtain a compressed load spectrum. Comparing with the load spectrum editing method based on S-transform，it is found that the time compression of the compressed load spectrum obtained based on the GST method is larger，and the compressed load spectrum basically matches with the original load spectrum in terms of statistical parameters，power spectral density，rainflow counts，fatigue life and damage distribution. The results show that the GST method is suitable for editing the load spectrum of automotive components. It can provide an effective means to improve the efficiency of durability bench tests of automotive components.

In order to improve the intelligence of fastener disease diagnosis，a fastener condition diagnosis method is proposed based on vehicle dynamic response data and generalized demodulation time-frequency analysis combined with sparrow search algorithm-support vector machine （SSA-SVM） model. The acceleration signals of the normal and abnormal sections of the fastener are collected，and the short-time Fourier transform and the maximum overlapping discrete wavelet packet transform are used to preprocess the signal data. The generalized demodulation time-frequency analysis method is used to decompose the signal，and the effective value，energy contribution rate and wavelength of the main information components are calculated as the characteristic index. The characteristic index is trained by the joint SSA-SVM model to construct the classification model. The results show that the accuracy of the method is 97.50%，and several evaluation indicators are used to verify that its effectiveness and accuracy can meet the actual needs.

To accurately extract fault feature information under strong background noise，a multi-scale improved differential filter （MIDIF） is proposed for rotating machinery fault diagnosis. The rotating machinery vibration signal is decomposed into a series of multi-scale improved differential filter signals using MIDIF. In view of that the MIDIF filtered signals exhibit varying extents of validity in revealing fault features，a weighted reconstruction method using correlation analysis is proposed in which the weighted coefficients are counted and distributed to the corresponding MIDIF filtered signals to highlight the effective MIDIF filtered signals and weaken the invalid ones. The weighted coefficients are multiplied with the MIDIF filtered signals under different scales to produce transient impulse components. The fault types of rotating machines are inferred from the fault defect frequencies in the envelope spectrum of the transient impulses. The results show that MIDIF is more accurate in extracting fault features than multi-scale average combination different morphological filter （ACDIF） and multi-scale morphology gradient product operation （MGPO），and that it provides an effective method for rotating machinery fault diagnosis.

Based on the problems of poor interpretability，as well as parameter increase and memory consumption caused by blind stacking layers in traditional fault diagnosis method based on deep learning，Neural ordinary differential equation （NODE） is introduced into mechanical fault diagnosis，the network structure of NODE for machinery fault diagnosis is constructed. In the constructed structure，the derivatives of the parameterized hidden states of the neural network are used to replace the discrete sequences of the specified hidden layers. By constructing a nonlinear relationship between fault data and fault types，an ordinary differential equation solver （ODE solver） is used to complete the classification of different fault types，and an end-to-end fault diagnosis model is formed. The proposed method is applied to mechanical fault diagnosis to build a specific NODE network model，and the classification task of different fault categories is accomplished through the input of fault data. The constructed model is applied to the fault diagnosis of spindle bearing in the aircraft engine，and compared with the fault diagnosis method based on residual network model. The experimental results show that the constructed model and residual network model have satisfactory accuracy. However，the constructed model not only reduces the memory consumption，but also reduces the number of model parameters by almost five times.

Aiming at the problems of bearings working in complex environments，where fault data are difficult to obtain in large quantities and the serious imbalance between the ratio of normal data and fault data resulting in insufficient in-depth model training and low diagnostic accuracy，a bearing fault diagnosis method based on LSGAN-Swin Transformer is proposed. The least-squares generative adversarial network is utilized to expand the imbalanced or lack of bearing dataset，and the windowed self-attentive network is introduced for bearing fault state identification. The proposed method is validated by using two date sets，and compared with SGAN and WGAN respectively. It is demonstrated that LSGAN generates data training models with higher accuracy. The proposed Swin Transformer （Swin-T） model is compared with CNN，AlexNet and SqueezeNet under small sample conditions，and the accuracy is improved by 34.85%，13.45%，and 12.95%，respectively. The classification effect of the model is evaluated by t-SNE visualization，and the results show that the LSGAN-Swin-T model can still meet the requirements in fault diagnosis better when the number of training samples is small，which provides a new idea for the research of bearing fault diagnosis under unbalanced data.

To solve the problem that the early weak fault diagnosis effect based on feature mode decomposition （FMD） is susceptible to the filter length L，frequency band segment K and mode decomposition number n，a diagnostic method is proposed in which a genetic algorithm is used to optimize the preset parameters of FMD，and the kurtosis，envelope entropy and modified adaptive envelope spectrum characteristic energy ratio as the comprehensive objective function. The method uses genetic algorithm to compare the comprehensive objective function values of each component signal decomposed by FMD under different preset parameters，and selects L，K and n corresponding to the maximum value as the preset parameters of FMD. The bearing fault type is determined by the envelope spectrum characteristics of the signal processed by FMD. The open bearing fault data of Western Reserve University and University of Cincinnati show that this method has good anti-noise ability and effective early fault diagnosis ability.

Based on the train-track coupling dynamics and probability density evolution theory，a random vibration model of train-track system considering both the crosswind and track irregularity is established. The N-dimensional hypercube point set is used to generate the discrete random frequency and phase representative point set. Based on the random harmonic function method and the harmonic superposition method，the random track irregularity excitation samples and the wind speed time-history samples are simulated respectively. The obtained two random excitations are introduced into the train-track coupling system to obtain the representative responses. The probability density evolution equation of representative response is solved using the bilateral difference method to obtain the time-varying probability density evolution distribution of the vibration response. The Monte Carlo method （MCM） is employed to verify the computational efficiency and accuracy of the proposed model. The results indicate that the probability density evolution method （PDEM） is appliable to the random analysis of vehicle-track system under double random excitations including crosswind and track irregularity. When the number of representative sample points is 300 and the screening radius is 17.7，a good calculation results can be obtained by the proposed model in this paper. The random response analysis regarding a single random input cannot express an accurate result of the vehicle-track system’s random dynamic characteristic，which indicates the required consideration of both random excitations of crosswind and track irregularity in the random vibration analysis of vehicle-track system.

In order to study the suppression mechanism of vortex-induced vibration （VIV） by adding aerodynamic countermeasures such as guide vanes near maintenance rails and spoilers on handrails，the displacement and pressure measurement on a large-scale sectional model was conducted in wind tunnel tests. Based on the spatial-temporal distribution and statistical characteristics of surface pressure，an aerodynamic wave hypothesis is proposed and further verified using the spectral proper orthogonal decomposition （SPOD） method. Moreover，the complex spatial-temporal pressure field is quantified and deconstructed with the spatial-temporal energy spectrum of the aerodynamic force，revealing the mechanism of vertical VIVs as well as its suppression by aerodynamic countermeasures in a streamlined box girder. The results reveal that there are three lock-in ranges of vertical VIVs for the original girder while the largest VIV response appears in the 3rd order lock-in range. The addition of guide vanes near maintenance rails reduces the maximum amplitude of model displacement by 53.1% whereas the installation of spoilers on handrails eliminates VIVs. The complicated pressure field on the girders surface can be expressed as a linear superposition of aerodynamic forces related to multiple spatial-temporal distribution modes induced by different excitation sources. The pressure on the original girder is dominated by the 1st order SPOD mode where the component at the fundamental frequency of bridge girder is the main ingredient. Meanwhile，the spatial-temporal distribution mode of aerodynamic force on the upper surface contribute more to the VIVs. The predominant aerodynamic forces mode distributing harmonic on the upper surface travels downstream，with the contribution value presenting a wave-like distribution，collectively referring to as the “aerodynamic wave effect”. The aerodynamic wave intensity acting on the upper surface is much greater than that of the lower surface. The propagation of the aerodynamic wave could be characterized by the monotonously decreasing phase lag between the distributed aerodynamic forces and the vortex-excited forces （VEFs）. The wavelength of the aerodynamic wave on the original girder is approximately consistent with the wavelength of the contribution value，which corresponds to the distance between the windward and leeward crash barriers. With the addition of guide vanes near maintenance rails，the predominant mode of aerodynamic wave on the upper surface is similar with that on the original girder while the wave intensity decreases，resulting in a reduction of VIV response. The spatial-temporal energy spectrum of aerodynamic force on the upper surface turns into a broadband distribution after the installation of spoilers on handrails，and the frequency lock-in phenomenon disappeared. Thus，VIVs were eliminated. This study provides a new perspective for the analysis of pressure field on girder surface and constructing mathematical models of the vortex-excited force on bridge girders，which could deeply reveal the mechanism of VIV.

Time-delay has significant influence on the performance of control systems and the stability of controlled structures，which，to a certain degree，limits the application of active control techniques in practical engineering. Although the time-delay classical optimal control method can consider the influence of time-delay，the time-delay problem needs to be transformed into a delay-free problem through introducing an augmented state vector associated with the control forces within the time-delay interval. Therefore，the augmented Riccati equation needs to be solved，leading to a large amount of computational cost for the design of control law. This paper is devoted to developing a time-delay explicit optimal control method of structures. The explicit time-domain expressions of dynamic responses are first established for the system with time-delay control. On this basis，the time-delay explicit optimal control law can be analytically derived from an unconstrained linear quadratic optimization problem. As the effect of time-delay control force on structural dynamic responses can be readily considered with the aid of the explicit time-domain formulation，the time-delay explicit optimal control law can be derived without augmented treatment of the state vector and solving of the Riccati equation. A numerical example involving a three-storey shear-type structure with an active controller subjected to seismic excitation is presented to investigate the effect of time-delay and validate the feasibility of the proposed method.

To address the problems of large number of random variables and time-consuming computation in the simulation of non-stationary non-Gaussian stochastic processes，a fast computation method of non-stationary non-Gaussian stochastic processes is proposed based on sample interpolation by combining the stochastic harmonic function. With the known of the target evolutionary power spectrum and target density function of non-Gaussian stochastic processes，the correlation function equations of non-Gaussian stochastic processes and underlying Gaussian stochastic processes are established through Mehler’s formula，and a fast calculation method for the evolutionary power spectrum of underlying Gaussian stochastic processes is proposed through interpolation method. Subsequently，a fast simulation method for non-stationary non-Gaussian stochastic processes is proposed by combining stochastic harmonic functions，The effectiveness of this method is verified by simulating single-point uniformly modulated non-Gaussian stochastic process and multi-point non-uniformly modulated non-Gaussian stochastic processes. The results show that，when calculating the evolutionary power spectrum of the underlying Gaussian random process under the condition of ensuring accuracy，the calculation time of interpolation solution is lower than that of Mehler’s formula solution，and as the number of excitations increases，the efficiency of interpolation solution in calculating the evolutionary power spectrum of the underlying Gaussian random process is more obvious. The proposed fast computational method of non-stationary non-Gaussian stochastic processes can effectively simulate the non-Gaussian stochastic processes with the target evolutionary power spectrum and the target density function.

Combined with the long-term observation data of three-dimensional ultrasonic anemometer at the deck of a long-span suspension bridge in the coastal area of Guangdong Province，the average wind characteristics of the wind field at the bridge site are statistically analyzed. Taking the wind speed exceeding 8 m/s as the standard of strong wind，the fluctuating wind characteristics of the bridge site are analyzed based on strong wind samples. The results show that the coastal areas of Guangdong are mainly affected by the southeast monsoon in spring and summer and the northwest strong wind in autumn and winter. The downwind turbulence intensity is obviously greater than the transverse wind and vertical turbulence intensity，and the ratio of each component is roughly I_u∶ I_v∶I_w=1∶0.86∶0.60. There is a significant positive correlation between gust factor and turbulence intensity，and the empirical formula recommended by Cao and Choi can better reflect the relationship between the two，and the empirical formula recommended by Cao is more suitable for coastal areas. Turbulence integral scale has a negative correlation with turbulence intensity. With the increase of turbulence intensity，turbulence integral scale first decreases rapidly and then tends to be stable. Based on the measured data，the empirical formula of turbulence integral scale and turbulence intensity is given，and the correlation between the two is significant. In the measured data，the downwind power spectral density is in good agreement with Kaimal spectrum，the transverse wind power spectral density is in good agreement with Von Karman spectrum，and the vertical power spectral density is in good agreement with Panofsky spectrum at high frequency band.

Steel spring floating slab tracks are equipped to reduce the vibration impact on precision instruments along the metro lines，but the ground vibration would be amplified at the natural frequency of the tracks. In order to address the negative impact of natural frequency vibration amplification on the surrounding environment of floating slab track，a full frequency control method considering frequency matching for environmental vibration in collaboration with metro vibration sources and propagation paths is proposed，which is based on the theory of periodic structure bandgap structure. The effectiveness of this method is analyzed by establishing a three-dimensional metro train-floating slab track coupling model and a finite element analysis model of track bed-tunnel- soil-row piles. The research results show that the ground vibration can be reduced about 4~7 dB at the natural frequency of the floating slab track plate by adjusting the band gap range of periodic pile to 7~9 Hz，eliminating the adverse effect of vibration amplification at the natural frequency of the track. Compared to ordinary tracks，the environmental vibration comprehensive control method proposed in this article has good vibration control effects and can effectively reduce the vibration level of sensitive points on the ground in the full frequency range.

In order to improve the energy dissipation capacity of the irregular steel joints of pseudo-classic architecture，the replaceable viscous damping device was set up at the location of decorated bracket to dissipate seismic energy. Six specimens of pseudo-classic architecture joints were designed and manufactured，including the single beam-column joint （SBJ） series and double beam-column joint （DBJ） series. The hysteretic curves and skeleton curves of the specimen and the viscous damper were obtained by the sine wave dynamic loading with displacement and frequency control，and the deformation and energy dissipation capacity of the specimen and the viscous damper were analyzed，respectively. The results indicate that the improved dynamic loading system has achieved good test results，and the failure mode of the irregular steel joint of pseudo-classic architecture is improved by installing a viscous damper at the decorated bracket position. The viscous damper has good working state after buckling in the plastic hinge area of the beam end of the specimen，and the hysteresis ring of the specimen becomes full gradually. The larger the damping coefficient of the damper，the fuller the hysteresis rings of the node and the stronger the energy dissipation capacity. With the increase of damping coefficient，the bearing capacity of specimens with controlled joints is increased by 18%~46% compared with that of without controlled，and the viscous damper increases the bearing capacity of specimens with double beam-column joints more significantly. The displacement ductility coefficient of the specimen is between 1.77 and 2.05，and the ductility of the specimen is slightly improved after the viscous damper is installed. The strength degradation coefficients are all about 1.0.

In order to consider the effect of liquid sloshing in an annular water tank on mechanical performance of a two-stage variable damping TMD，taking an actual high-rise structure as an example，a global model considering the water tank as a particle and the liquid-solid coupling model of the water tank under the full water state and the non-full water state are established by ABAQUS software. The seismic responses of the two-stage variable damping TMD under different liquid-solid coupling states are compared and analyzed. The results show that the amplitude and maximum damping force of the two-stage variable damping TMD considering liquid sloshing are larger under larger seismic excitation，and the sloshing effect of liquid inhibits the full development of the second-stage damping energy consumption of the two-stage variable damping TMD. With the increase of seismic excitation，the maximum base shear force of the liquid-solid coupling model is larger than that of the particle model，and the relative increase amplitude increases accordingly.

To study the influence of different degrees of steel corrosion and axial compression ratio on the seismic performance of corroded L-shaped reinforced concrete （RC） shear walls，the test specimens of 5 L-shaped RC shear walls with a shear-to-span ratio of 2.5 were subjected to accelerated corrosion by using dry-wet cycle and external current corrosion method，then the specimens were subjected to a pseudo-static test. The test results show that with the increase of corrosion degree，the bearing capacity of the specimens gradually decreased，and the decrease rate of positive （flange tension） bearing capacity was higher than that of the negative （flange compression）. The specimen deformation and energy dissipation capacity deteriorated to varying degrees，the stiffness degradation aggravated，and the percentage of shear deformation in the positive peak point increased. When the degree of corrosion was equal，with the increase of the axial compression ratio，the positive failure mode of the corroded specimen developed into small eccentric failure progressively. In the meantime，the positive bearing capacity of the specimens first increased and then decreased，while the negative bearing capacity of the test specimens gradually increased，and the increase rate of the negative bearing capacity was greater than that of the positive； the deformation capacity of the specimens constantly decreased，and the decrease rate of the positive deformation capacity was greater than that of the negative； the energy dissipation capacity，shear deformation and percentage of shear deformation of the specimens all decreased continuously.

Recent earthquake damage investigations found that a large number of reinforced concrete frame buildings were heavily destroyed at beam-column joints and columns，without forming the beam-hinging mechanism expected in the design. Installing reinforced concrete wing walls beside the existing columns remains a fundamental and effective strengthening method，by improving seismic performance of both the columns and the joints，while promoting a beam-yielding mechanism. Two 1/2-scale frame specimens were manufactured，and one of them was strengthened by post-installation wing wall. By quasi-static tests，hysteretic behaviour，deformation capacity，energy dissipation power and failure mode of the two specimens were examined. The results show that the stiffness，bearing capacity and energy dissipation capacity of the strengthened frame were significantly improved. After strengthening，failure mode of the frame was changed from joints shear failure to expected beam-hinging. The efficiency and applicability of wing wall installation method were validated for strengthening existing frame structure buildings with seriously weak beam-column joints.

The fifth generation “seismic ground motion parameters zonation map of China” （GB 18306―2015），which was promulgated and implemented in China，introduced the vary rare earthquake effect for the first time. However，the current seismic design specifications still adopt the three-level defense principle. The seismic design for vary rare earthquake has become one of the urgent issues that need to be addressed in structural seismic design. Based on the identification method of continuous wavelet transform，this paper selects 12 pulse-like ground motions and 12 non-pulse seismic motions recorded in the Turkey mega earthquake on February 6，2023. The incremental dynamic analysis （IDA） is conducted on continuous pipelines and ductile iron pipelines to evaluate their seismic fragility. The fragility analysis results are compared with the failure probability obtained by empirical statistical method. The results show that the effect of pulse-like ground motions significantly increases the probability of serious structural damage for buried pipelines with different forms. Compared with continuous pipelines，ductile iron pipelines are more prone to damage underground motions，and are more sensitive to the pulse-like ground motion. The empirical statistical results based on actual seismic damage data are slightly lower than the failure probability of pipelines under non-pulse earthquake motion，but significantly underestimate the damage of buried pipelines under pulse earthquake motion. In this paper，the failure probability of different types of buried pipelines under pulse-like seismic motions is given，and the research results can provide a strong theoretical basis for the risk assessment and seismic design of buried pipelines under very rare and pulse-like ground motions.

There are a large number of ultra-large slope bridges in the rack railway line，and the settlement of bridge piers is difficult to avoid. It leads to the decrease of the smoothness of the railway line and threaten the safety and smoothness of the train. To solve this problem，based on the theory of vehicle-rack（track）-bridge dynamic interaction and gear dynamics，a coupled dynamic model of mountain vehicle-rack（track） -bridge system is established. The dynamic model considers the nonlinear meshing behavior of gear-rack and nonlinear contact behavior of wheel-rail in detail. The meshing behavior of gear-rack and the dynamic characteristics of vehicles under three different pier settlement modes （single pier settlement，continuous pier settlement and spaced pier settlement） are investigated，and the influence of different pier settlement modes on the vibration of vehicles is compared. The results show that the influence of pier settlement on the rack railway system is mainly reflected in the vertical and longitudinal acceleration of the vehicle，and the main frequency of vibration is 1~2 Hz and 8~9 Hz respectively. The effects of single pier settlement on the basic vibration characteristics of the rack-bridge system are similar to those of double pier settlement. But compared with double pier settlement，the effects of single pier settlement on the longitudinal acceleration of the vehicle are more significant，and the fluctuation of the meshing frequency is also significantly increased. Pier settlement will cause the increase of gear offset，and then lead to the instability of gear-rack meshing. When pier settlement is 6 mm，the problem of meshing apart begins to appear，which seriously threatens the operation safety of vehicles.

A large number of high-pier rigid frame bridges in the canyon areas are located in near-fault regions （hereinafter referred to as near-fault），and the seismic analyses should comprehensively consider the near-fault effect，site effect，and fluid-structure interaction when they are located in the water environment such as rivers，reservoirs，etc. Currently，most near-fault seismic records are used as consistent inputs，which may underestimate the seismic response of the bridges. At the same time，the discussion on the correlation between the seismic sources，site parameters，and seismic response of the bridges is unexplored. In this paper，the stochastic finite fault method and the boundary element method are combined to generate the multi-dimensional and multi-point ground motions of the overlying water-layer canyon sites near faults，and the analysis of the seismic response of the deep-water，large-span，high-pier rigid frame bridge in the near-fault canyon site is developed. The sensitivity of the response of piers and bearings to the seismic source and site parameters is investigated from the perspective of the whole physical process between the seismic source and the structure. The results indicate that the bridge response is most sensitive to the rupture surface size. On the whole，the influence of source parameters on the bridge response is more significant than that of site parameters. The site effect leads to the difference of the mean values of curvature ductility ratios of two main piers in longitudinal and transverse directions to be 85% and 88%. There are differences in the sensitivities of the main piers and bearings to each parameter. When the dip angle of the fault is between 33°~60°，the seismic response of the bridge shows a trend of increasing first and then decreasing，and the curvature ductility ratio of the main pier can differ by 35%. The water layer has an inhibitory effect on ground motions； however，the amplification effect of hydrodynamic pressures on the seismic response of the bridge is more prominent.