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.