Stochastic subspace identification （SSI） generates spurious modes in the process of identifying the dynamic characteristics of high-rise structures，which interferes with the automatic tracking of dynamic characteristics. This article has proved that the non-white noise excitation is one of the causes of spurious modes，and further proposed a signal reconstruction method based on multivariate variational mode decomposition （MVMD） for non-white noise excitation，which removes the influence of non-white noise excitation in signals and eliminates spurious modes. A Single-Pass clustering algorithm is proposed to eliminate discrete spurious poles. The above algorithm has been applied to on-site monitoring data of super high-rise structures，achieving long-term automatic identification and tracking of dynamic characteristics.

The key to damage pattern recognition lies in digging and classifying damage features from the response data of civil structures. To this end，a stack auto-encoder network with several auto-encoder hidden layers and a Softmax classification layer is built for analyzing frame structures. A hybrid learning mechanism is adopted to combining unsupervised and supervised learning strategies. Finite element analysis is used to generate the transmissibility function samples corresponding to different scenarios of a frame structure. The transmissibility samples are then divided into training，validation，and test sets. The parameters of the auto-encoder hidden layers，such as the weights and bias，are determined by a pre-training strategy in order to avoid the phenomenon of network over fitting. A fine-tuning step is employed to adjust the pre-trained network parameters，and the network hyper parameters are further adjusted based on the validation set. The measured transmissibility data are input into the network to evaluate the damage of the frame structure. The analysis results show that the proposed method can effectively extract and classify the damage features. Both the single and double damage scenarios at the frame joints were identified with higher accuracy and better anti-noise ability than the traditional shallow neural network.

Establishing human body dynamics model to obtain human natural vibration frequency is a common scientific challenge in various fields such as civil engineering，traffic engineering，aerospace，rehabilitation medicine and so on. The spring-mass-damper （SMD） model is most commonly used in previous studies，which actually is not consistent with the distribution characteristics of human mass and stiffness along the height. In this study，a distributed parameter dynamics model of the human body with a pair of biomechanical forces is proposed，and the analytical solution of human natural frequency is theoretically derived. Therefore，a frequency recognition method based on gait tests is proposed. 247 subjects are organized to conduct gait tests，and their stiffness and natural frequency are identified. The rationality and applicability of the proposed model are verified from multiple perspectives： by fitting the probability distribution of results，comparing the results with other researches，and analyzing the results across different age groups.

As a method for operational modal analysis （OMA），the Bayesian FFT algorithm has garnerd significant attention for its high accuracy and efficiency，as well as its ability of uncertainty quantification. However，different cases of OMA （e.g. well-separated mode，closely-spaced modes，and multi-setup OMA） require different optimization strategy，and it is tedious in computer coding. A new framework is proposed in this paper to unify the above-mentioned cases of OMA，and the implement is simplified as a consequence. Regarding the structural modal response as a latent variable，the single-setup and multi-setup Bayesian OMA is cast as latent variable models，which have been deeply investigated in statistics. An expectation-maximization （EM） algorithm is developed for both single-setup and multi-setup OMA. The introduction of latent variables decouples the parameter optimization in EM，and Louis identity is employed to calculate the Hessian matrix. Two field tests are applied to verify the performance of the proposed approach，with a comparison to the existing algorithm. Consistent results are obtained，and a great advantage in efficiency is observed in the case of closely-spaced modes. The proposed latent variable model unifies the cases of Bayesian OMA，with the advantage of simplified implementation and fast computation. It also paves a way for a further improvement of Bayesian OMA，e.g. with the approach of variational Bayes or Gibbs sampling.

In the realm of stochastic nonlinear response analysis for large and intricate structures，the Monte Carlo simulation method stands out as a pivotal approach. However，its widespread practicality is hampered by its exorbitant computational costs. To surmount this challenge，researchers have endeavored to develop the active learning-based Gaussian process surrogate model algorithm. Despite its promise in reducing computational expenses，the optimization strategy associated with active learning necessitates further refinement to meet the exacting demands of engineering applications. For this purpose，we introduce a search function endowed with ‘intelligent’ attention capabilities. This function is meticulously crafted to concentrate on exceedingly high-risk one-sided tail events in engineering scenarios. By incorporating this search function，we have engineered an algorithm that surpasses existing methodologies. Our algorithm finds successful application in the analysis of complex adhesive anchoring structures within subway tunnel rings and linings. Compared to conventional methodologies，our algorithm exhibits a remarkable 30% reduction in the estimation error of single-tailed probabilities. This advancement facilitates a more precise estimation of the one-tailed probability distribution governing the stochastic response of complex structures. Consequently，it enhances the precision of assessing the occurrence probability of extreme events. These findings yield invaluable insights for decision-making processes in pertinent engineering domains and insurance sectors.

There are two kinds of stochastic seismic ground motion simulation methods： frequency-domain methods and time-domain methods. Based on the time-domain model of single filtered white noise，this paper proposes the time-domain representation for simulating stationary and non-stationary seismic ground motion processes. In essence，the time-domain representation can be regarded as linear superposition of deterministic functions modulated by a series of standard orthogonal random variables，and the set of orthogonal random variables is defined as the form of random orthogonal functions to achieve efficient dimension-reduction. Therefore，by introducing three kinds of random orthogonal functions，i.e.，Legendre orthogonal polynomial of non-Gaussian type，Hartley orthogonal basis and Hartley orthogonal elementary of Gaussian type，the acceleration process of seismic ground motion can be accurately represented in the time-domain model with only one elementary random variable. Numerical examples of seismic stationary ground motion process show the effectiveness of the proposed method，which is superior to the Monte Carlo method. The analysis of fully nonstationary seismic ground motion shows the engineering applicability of the proposed method.

The traditional additional acoustic black hole （ABH） structure is mainly designed for vibration suppression of plate structures，but it is difficult to be applied to pipe structures that are widely available in engineering. In order to solve the vibration suppression problem of pipe structures，a new additional ABH device，‘Circular Spiral ABH Damper （CSABH）’ is proposed to be applied to pipe structures. By designing the ABH area in the form of a spiral，the modal density of the damper is increased，and a better coupling with the main structure is achieved. The results show that the CSABH has good wave aggregation characteristics and can achieve a vibration suppression of 20~5000 Hz for the pipe. Besides，when the pipe constraints and temperature conditions are changed，the CSABH with the same parameters can still play a good wide frequency damping effect，showing the robustness of the damping. The wide frequency，high efficiency and high robustness of CSABH in the vibration control of pipeline structures are verified experimentally.

Impact load is a common load，but it is also very special. Compared with other persistent loads，impact load has the characteristics of short duration and large output energy，leading to the transient vibration which may affect the system’s operation safety. In this paper，the active magnetic bearing （AMB）-flexible rotor was installed on an elastically supported base. The vibration characteristics of the elastic supported base under five types of impact loads，including double half-sine wave，half-sine wave，sine wave，triangle wave，and double triangle wave，were investigated. The influence of different impact load parameters on the acceleration of the base was obtained. In order to suppress the rotor vibrations，relative to the base induced by impact loads，a transient vibration compensation control strategy based on the base acceleration was derived. The theoretical and experimental results indicate that the elastic supported base and the AMBs-flexible rotor system installed on it both exhibit obvious impact characteristics under impact loads. These impact characteristics vary with different types of impact loads. The effect of base shock excitations on the rotor vibration can be effectively suppressed by the proposed algorithm.

Aiming at the issue of inter-shaft bearing waviness in a dual rotor system，the dual rotor-bearing system of external rotor with variable cross section was taken as the research case. The dynamic model of the dual rotor-bearing system was established based on the Finite Element Modeling （FEM）. The waviness of the inner and outer ring raceways and the rolling body of the inter-shaft bearing were considered in the model. The fourth order Runge-Kutta numerical method was used to solve the equations，and the influence of waviness excitation on the amplitude-frequency response curve and spectral characteristics of the system was analyzed. The results show that when there is waviness in the inner and outer ring raceways，the system exhibits a combination frequency of the inner and outer rotor rotation speed frequency as well as cage rotation speed frequency. And when there is waviness in the rolling body，the system has an even times of the rolling body self-rotation speed frequency. When the rotor is unbalanced，the outer ring raceway waviness will amplify vibrations in the resonance region of the outer rotor main excitation. The vibration of the system will increase in the whole speed range with the increase of the waviness amplitude，while the vibration responses of the inner ring raceway waviness and the unbalanced excitation will appear similar to the same frequency and reverse phase phenomenon in the second resonance region of the inner rotor main excitation. The vibration of the system will decrease with the increase of waviness amplitude，while the vibration in other regions will increase. Compared with the high rotating speed region，the waviness of the rolling body significantly impacts on the vibration characteristics in the low rotating speed region.

In this paper，the effect of top drive control on stick-slip and bit-bounce was studied numerically based on a three-degree-of-freedom lumped parameter model considering coupling between axial and torsional vibrations of drill strings. The simulation results indicate that although the tuned k-c control can inhibit the stick-slip and bit-bounce the drill string vibration system to a certain extent，the suppression effect of stick-slip and bit-bounce in the drill string vibration system is not ideal when the input angular velocity is high and the nominal drilling pressure is low，or the input angular velocity is small and the nominal drilling pressure is large. The tuned I-k-c control can successfully eliminate the influence of input angular velocity and nominal drilling pressure changes on stick-slip and bit-bounce，so that no matter what the input angular velocity and nominal drilling pressure values are，the bit speed will remain stable around the given input angular velocity，reducing the fluctuation of WOB，TOB and axial displacement. Therefore，compared to top-drive tuned k-c control，tuned I-k-c control is more efficient in suppressing the stick-slip and bit-bounce of drill string vibration system.

In the phenomenon of brake noise，the parametric uncertainty and correlation inevitably exist in the automotive brake systems，leading to some uncertainty and correlation of the system response. To address this problem，the uncertainty and correlation analysis for the stability responses of brake systems was carried out. A multi-ellipsoidal convex model was used to depict the uncertainty and correlation of system parameters，and the stability responses of system were characterized by the unstable modal damping ratios. The Monte Carlo simulation，the first-order perturbation method and the second-order perturbation method were respectively combined with the multi-ellipsoidal convex model respectively，and three uncertainty analysis methods of system stability responses were proposed. Based on the Monte Carlo simulation and the first-order perturbation method，two correlation analysis methods of system uncertain responses were developed respectively. The combinatorial methods for establishing the ellipsoid domains of system responses were presented by combining the uncertainty analysis and correlation analysis methods. A numerical example was given to verify the effectiveness of the proposed methods. The analysis results demenstrate that the proposed methods can effectively obtain the boundary intervals，correlation coefficients and ellipsoid domains of system responses，and the methods have high computational accuracy and efficiency.

The existing shell model is accurate in the frequency band of 0~500 Hz，making it highly suitable for tire vibration analysis. However，the modal properties of the tire belt cannot be obtained separately and the freedom as well as the number of parameters required by the model increases，because the shell model couples the tire belt and sidewall. Therefore，this shell model was improved in this paper. The shell model for simulating the tire belt remained unchanged，whereas，by using the method for approximating the sidewall used in the ring model and plate model of tire，the two-dimensional shell model for simulating the tire sidewall was replaced by an elastic foundation to simplify the boundary conditions of the tire belt and reduce the number of parameters related to the tire sidewall. The solving method for the improved shell model was developed to calculate the modal frequency and the modal shape of the tire belt. The validity of both the improved shell model and its solving method was demonstrated by an experiment.

In order to improve the climbing ability of rack vehicles，the gear-rack system is added to the traditional rail vehicles. Aiming at the problem that there are many kinds of gear-rack systems in the world at present，and the diversity of gear-rack systems equipped with them leading to the dynamic characteristics difference of rack vehicles，this paper considers the impact of gear-rack meshing on the basis of analyzing the generation mechanism of gear-rack meshing excitation，the rack vehicle coupled dynamic models with two kinds of Strub system，double row teeth Abt system and Locher system are established，and experimental verification on the model are carried out； Based on the model，the gear-rack meshing behavior of rack vehicle running at different speeds on the engagement section of the ramp is analyzed，and the influence of track irregularities on the gear-rack meshing center distance error is explored； On this basis，the wheel/rail action and car body acceleration of the rack vehicle are studied，and the rack vehicle safety are analyzed as well as stabitity. The results show that there are significant differences in the dynamic characteristics of rack vehicles with different gear-rack systems，and the Locher system has the best dynamic characteristics； The gear-rack meshing behavior of coaxial Strub system and double row teeth Abt system is poor and affected by the track irregularity obviously. The maximum impact value of the gear-rack contact force is 20.3 kN，and the meshing center distance error is 3.73 cm； The safety of coaxial Strub system and double row teeth Abt system is poor，and the maximum wheel/rail vertical force of double row teeth Abt system is 51.7 kN； The car body stability of the differential shaft Strub system is the worst. The maximum car body acceleration is 0.033 m/s²，and the stability index is 1.27. The conclusions offer theoretical support for the design，safe operation，and maintenance of mountain rack railways in China.

Vortex shedding and drift are key characteristics around the bridge girders during VIVs，and therefore it is necessary to reveal VIVs mechanisms of bridge girders from the perspective of vortex dynamics. A simplified vortex model was constructed from the perspective of aerodynamic work. Taking a typical streamlined-closed box girder as an example，a simplified wortex model was constructed from the perspective of aerodynamic work. Combined with the aerodynamic time-frequency characteristics of the bridge girder from wind tunnel experiments and the flow field characteristics around the girder based on numerical simulation method，the above model was verified and then the multi-order VIVs lock-in range mechanisms of the girder were revealed. The results indicate that the Strouhal number of the separation vortex characterizes energy effects of the vortex aerodynamics，which can be expressed as a positive integer multiple of the ratio of vortex-drift velocity to oncoming flow velocity，implying that a separation point can excite multiple VIVs lock-in ranges. There were 3 order lock-in ranges of vertical VIVs for the girder. Both the 2nd and 3rd lock-in ranges are excited and sustained by the large-scale separated vortexes separating at the leading edge and periodic drift in the drift distance between the separation point and the trailing edge. Especially，it takes about 2 and 1 vibration cycle for the separation vortexes to traverse the drift distance in the 2nd and 3rd order VIVs lock-in ranges，respectively. Therefore，they are dominated by the 2nd and 1st order simplified-vortex modes originating from the leading edge，respectively. This study verifies the rationality of the simplified-vortex model to deduce the vortices evolutionary characteristics around the bridge girder and provides a new methodology for VIVs mechanism of the bridge girders.

In order to explore the mechanical properties of high-damping thick-layer rubber bearings，this paper studies the force characteristics of horizontal shear and vertical compression of high-damping thick-layer rubber bearings under vertical compressive stress. A model considering horizontal shear deformation is established，and a vertical stiffness correction theory is proposed based on compressive stress changes. To verify the accuracy of the theoretical model，three types of high-damping thick-layer rubber bearings with different first shape coefficients were designed for horizontal quasi-static shear and vertical compression tests. The results show that the equivalent horizontal stiffness and equivalent damping ratio of the high-damping thick-layer rubber bearing are changed by the restraint effect of the internal steel plate. As the vertical compressive stress increases，the horizontal equivalent stiffness gradually decreases. In the vertical compression test，as the vertical pressure increases，the vertical compressive stiffness presents nonlinear strengthening characteristics. Through the comparative analysis of theoretical and experimental results，it can be seen that the mechanical model of horizontal shear deformation constructed in this paper can better describe the mechanical properties of high-damping thick-layer rubber bearing in horizontal shear，and the vertical stiffness correction theory can accurately calculate its vertical stiffness. The deviations from the test results under different working conditions are all within 5%.

In order to reduce the tube area proportion of the traditional frame-core tube （FCT） structure system and improve the structural economy，a high-rise structural system of the frame-distributed tubes-core tube （FDCT） is designed. The distributed tubes and rocking system are combined to form the frame-distributed rocking tubes-core tube （FDRCT） structural system，which can control the deformation mode of the structure. To reduce the adverse effects of higher modes on high-rise structures，the frame-distributed bi-rocking tubes-core tube （FDBRCT） structural system with tuned damping performance is further proposed. The dynamic models and equations of the structure are established，and the stationary random vibration analysis is carried out，which preliminarily proves that the FDBRCT structure can reduce the dynamic response of the structure more effectively. By comparing and analyzing the structural time-history analysis results of the FCT，FDCT，FDRCT and FDBRCT，the seismic capacity of the FDCT structure decreases is due to the stiffness weakening. The FDRCT structure improves the uniform degree of structural deformation，and the upper floors acceleration decreases，but the roof displacement increases. Compared with the FDRCT structure，the maximum of inter-story drift ratio of the FDBRCT structure increases significantly and the structural deformation is more uniform. Besides，the roof displacement response and internal force demand decrease appropriately. The distributed bi-rocking tubes with tuned damping brings on better seismic capacity and damping performance of the FDBRCT structure，which can improve the economy at the same time.

The durability issue of multi-age masonry structures subjected to acid rain has become increasingly prominent，but a complete time-varying model of structural durability has not been formed at home and abroad. To study the relationship between the evolution of material properties and masonry properties，accelerated corrosion tests were carried out on mortar with different mix ratios，bricks，and masonry，and a compressive strength model of masonry components considering the number of acid rain erosion cycles was established. Based on the sample data of masonry in natural environment，the mathematical relationship between the degradation degree of mechanical properties of in-service masonry structures and their service life under the action of acid rain erosion was established. The typical structure method was used to analyze the seismic fragility of a two-story constrained masonry structure，and the influence of different parameters on the fragility curve and failure probability of constrained masonry structures under acid rain erosion was discussed. The results show that the probability of severe damage and collapse of restrained masonry structures under the action of acid rain erosion increases gradually with the increase of service life under the condition that other factors remain unchanged and the intensity of local vibration is higher.

Aiming at the problem that the effectiveness and computation cost of the maximum second-order cyclic stationarity blind deconvolution （CYCBD） algorithm are affected by parameter setting，the crest of the harmonics spectrum （HSC） was used as an evaluation index to determine the length of the CYCBD filter adaptively，and the calculation cost of the optimization process was balanced by the method of encoder time series reconstruction. The bearing fault order is calculated and the cycle frequency is set according to it. The pulse number of time series reconstruction is determined according to the fault order. The central difference method （CDM） is used to calculate the instantaneous angular speed （IAS） of the reconstructed signal. The filter length of CYCBD was adaptively selected with the HSC as the evaluation index using the equal-step search strategy. The spectrum corresponding to the maximum HSC is calculated to achieve fault feature extraction. The simulation and experimental data analysis results show that the proposed method can adaptively select the filter length，which has an obvious effect on reducing the cost of the CYCBD algorithm，and is effective for rolling bearing fault feature extraction.