To enhance the seismic mitigation performance of conventional damped outrigger （CDO） system，this study investigates the seismic performance improvement of inerter-negative stiffness damped outrigger （INSDO） system，which is based on the three-element passive mitigation system consisted of inerter，stiffness and damper. The Clough-Penzien spectrum model is adopted to simulate stationary stochastic seismic excitation，and the motion equations of the structure-damper-excitation system are then expressed utilizing augmented state space method. The root-mean-square （RMS） of the structural response under stochastic excitation is calculated via the solution of Lyapunov equation，and optimal parameters of INSDO system are determined by multi-objective optimization method based on maximum harmful inter-story drift and acceleration control. The seismic performance of INSDO system under typical natural seismic records is further evaluated. Results indicate that compared with the CDO system，the optimum INSDO system can reduce the bottom average story drift RMS by 57.97% and the top average absolute acceleration RMS by 36.99% under El-Centro and Kobe excitations，which further verifies the effectiveness of multi-objective optimization method. Compared to the introduction of inerter or negative stiffness element alone，the combination of two kinds of element can further amplify the displacement of the damping element，and realize the seismic performance enhancement of INSDO system by improving the energy dissipation ratio of damper and seismic input energy.

An efficient and accurate evaluation of the seismic performance of long-span continuous rigid frame bridges using a simplified method is essential in the design and strengthening of such bridges. As a simplified method to evaluate the seismic performance of bridges，the endurance time method can be used to simulate the whole process of bridge from intact to collapse with nonlinear time history analysis only once. In order to study the applicability and accuracy of the endurance time method in evaluating the longitudinal seismic performance of continuous rigid frame，this paper investigated a long-span continuous rigid frame bridge with corrugated steel webs. Three acceleration time-history curves were generated based on the design response spectrum of China highway bridge seismic code. In addition，16 natural ground motions were selected for incremental dynamic analysis. The seismic response characteristics of continuous rigid frame with corrugated steel webs were compared and studied. The seismic response characteristics of continuous rigid frame with corrugated steel webs were comparatively studied by endurance time analysis method and incremental dynamic analysis. Research results demonstrate that the endurance time analysis method results are within the envelope of the incremental dynamic analysis results. The time-history analysis results are within the envelope of the incremental dynamic analysis results. The median value of the endurance time analysis method has an allowable error with the mean curve of incremental dynamic analysis. Therefore，Endurance time analysis method can be used to evaluate seismic performance of the long-span continuous rigid frame bridge.

Directed at the proposed earthquake reduction system，named the tuned tandem mass dampers （TTMD），the optimized analysis of the multi-degree-of-freedom （MDOF） structure-TTMD system has been investigated in frequency domain by the particle swarm optimization. The seismic simulation of the MDOF structure-TTMD system has been established under earthquakes. Considering different types of seismic records，the control efficiency of TTMD for the structural seismic responses was analyzed in the time domain and compared to that of the tuned mass damper （TMD） with the equal total mass ratio. Further taking into account the structural stiffness of the -10% and -30% degradations，the earthquake reduction behaviors of TTMD were scrutinized for the seismic responses of the structure with the stiffness degradation. It is found in terms of numerical results that the TTMD outperforms the TMD in seismic performance and robustness. Likewise，the TTMD has a drastically reduced damping demand，thus being an enhanced earthquake reduction system.

Through shear tests on small lead-core rubber bearings，the effects of bearing shear strain，compressive stress and loading frequency on the bearing's equivalent horizontal stiffness，post-yield stiffness，yield force and equivalent damping ratio are studied. The results show that： With the increase of shear strain，the equivalent horizontal stiffness and the post-yield stiffness of the bearing decrease，the yield force increases，and the equivalent damping ratio decreases linearly； with the increase of the vertical compressive stress，the equal the effective horizontal stiffness decreases，the stiffness decreases linearly after yielding，and the yield force and the equivalent damping ratio increase linearly； the loading frequency has basically no effect on the shear performance of the bearing and can be ignored； within 100% of the shear strain，apply the shear strain and compressive stress did not cause damage to the isolation bearing； large deformation and large compressive stress above 100% shear strain will cause the bearing to enter into plastic，causing partial permanent damage to the bearing. Suggestions that the working conditions need to be designed according to the actual needs of the shaking table test are put forward. The correction coefficient of the Japanese code equivalent horizontal stiffness calculation formula is proposed，which is compared with the measured value of the shaking table test to improve the accuracy.

Soilbag，with the advantages of high bearing capacity，high damping ratio and low cost，is a kind of base isolation material which is suitable for the low- and mid-rise buildings. The relationship between shear stress-shear strain，dynamic characteristic parameters and shear strength of stacked soilbags were analyzed and discussed through a series of laboratory cyclic simple shear tests. The variation of dynamic shear modulus and equivalent damping ratio of stacked soilbags under different vertical stresses and shear strain amplitude was further investigated. And the influence of number of load cycles on the dynamic characteristic parameters and shear strength parameters was also studied. The test results show that the peak shear stress and dynamic shear modulus increase while the equivalent damping ratio decreases with the increasing number of load cycles under small-strain condition； when the shear strain is large enough，the interface slippage and the strain softening occur on stacked soilbags. The peak shear stress （shear strength） decreases with the increasing number of load cycles. And the variation of dynamic characteristic parameters is totally opposite to that under small-strain condition. The internal friction angle of the shear strength parameters of stacked soilbags gradually decreases with the increasing number of load cycles while the additional cohesion force increases and tends to be stable during the test. The energy is dissipated through the shear deformation of soil particles inside bags and the interlayer slippage of stacked soilbags under high shear strain amplitude.

To address the issue of weak features related to faulty rotating parts in Instantaneous Angular Speed（IAS） signal，this study proposes a Average Down-Sampling Multi-Period Differential Means（ADSMPDM） scheme to enhance fault features. Firstly，based on the estimation characteristics of the IAS，the average down-sampling of the IAS signal is studied and its features of suppressing random noise are obtained. Secondly，the ADSMPDM scheme is proposed to enhance the features related to the fault in the IAS signal based on the advantages of the average down-sampling （such as noise suppression，low computational cost and low storage space） and accumulative characteristic of multi-period differential means. Finally，the features related to the fault are revealed by order spectrum analysis. By using Simulations and experiments and comparing with fast kurtogram，multipoint optimal minimum entropy deconvolution adjusted，discrete random separation and spectral amplitude modulation，the effectiveness and advantages of the ADSMPDM algorithm in enhancing gear and bearing fault feature components are verified.

To address the low accuracy in diagnosing faults in wind turbine bearings caused by the different characteristic distribution of the source domain data and the target domain data，a fault transfer diagnosis method using improved residual neural networks is proposed. The convolution kernel and pooling kernel are set to a size suitable for the convolution operation of one-dimensional signals，allowing for direct extraction of fault features from the bearing vibration signals； Both batch normalization and case normalization are used in the one-dimensional residual network to further enhance the feature extraction ability of the model； In the model training stage，a new loss function is constructed based on the multiple kernel maximum mean discrepancy between the source domain data and the target domain data to improve the transfer learning and classification ability of the model. The effectiveness of the method is verified by conducting the experimental data of the faulty bearings. The results show that the proposed method can effectively extract the important features of bearing faults and achieve the transfer diagnosis and accurate classification of the bearing faults. This holds true even under varying speed operation conditions and when the bearing fault vibration signals are disturbed by some noise components. Therefore，this work provides a useful strategy in developing intelligent fault diagnosis technology of rotating machinery under complex working conditions.

The variable-length dual-flexible manipulator is composed of a flexible joint and a flexible load，which is affected by flexibility，friction，and time variation of parameters. It will vibrate in the process of moving，which will reduce the tracking accuracy of the end-effector. In this paper，the fuzzy tuning PI control strategy based on disturbance observer is used to control the output speed of the dual-flexible manipulator servo system. The vibration of the manipulator can be suppressed indirectly by controlling the speed fluctuation of the flexible load. Based on the assumed modal method and the Lagrange principle，the dynamic equations of the dual-flexible manipulator are established. A low pass filter in the disturbance observer is designed according to the robust stability theorem，so that the disturbance observer can satisfy the stability of the controller parameter time-varying and the controlled object parameter perturbation jointly. The effectiveness of the proposed method is verified by numerical simulation and control experiments of the dual-flexible manipulator servo system. The experimental results show that the proposed control strategy can better eliminate the influence of parameter time-varying and flexibility on the output speed，and improve the control precision of the end-effector.

The synchronization factor is a measurement for the consistency of actions between individuals in a jumping crowd，as well as a key metric in the modeling of crowd jumping loads. Most of the existing synchronization factors are defined as mean parameters during a long period of time，and thus cannot accurately reflect the time-varying characteristics of individual differences between jumpers. Their calculation is based on ground reaction force or feature point trajectory records that can only be obtained under laboratory conditions，making it difficult to apply them to the safety operation and maintenance of the engineering structures in actual scenarios directly. In this regard，this paper proposes a new time-varying synchronization factor for crowd-jumping loads. By introducing multiple objects tracking technology to monitor the real-time synchronization variation of the subject jumping processes as the basis for the factor calculation，this study carries out a multi-person jumping experiment with a wireless force measurement shoe pad. By comparing with the test results，the validity of the proposed time-varying synchronization factor and the effectiveness of the multi object tracking technology are verified. The results can be used for the intelligent operation and maintenance of the engineering structure，as well as the simulation of the time-varying crowd jumping loads.

With the rapid development of offshore wind power in recent years，the floating offshore wind turbine is proposed to capture more abundant and lasting wind energy in the deep sea，which has become the main direction of wind energy development. Due to the special structures and complex environment，the accurate calculation and analysis of floating offshore wind turbines will be particularly important for a multi-body system. In this paper，the coupling dynamic model of a floating offshore wind turbine is deeply studied. The improved 14-DOF coupling dynamic model of spar floating offshore wind turbine under complex working conditions is established，including an aerodynamic model，hydrodynamic model and structural analysis model，which can accurately calculate its dynamic response and verified by numerical simulation. The main improvements are as follows： expanding its scope of application without using small approximation of the angle in the coordinate rotation matrix； considering the conversion relationship between angular velocity and Euler angular velocity，the motion equation of floating offshore wind turbine with wider application range and more accuracy is derived. Besides，considering the influence of fan blade torsion angle on blade deformation，the accurate in-plane and out-of-plane response of the blade is obtained. Meanwhile，the potential flow theory is used to calculate the hydrodynamic force in order to solve the limitations of the traditional Morison equation algorithm. The simulation analysis shows that the model proposed in this paper can calculate the dynamic response of floating offshore wind turbine system more accurately with wider applicability.