Based on the actual project in Dalian，this paper studies the dynamic interaction （SSSI） of the double tunnel sand bridge pile system under earthquake through shaking table test，obtains the dynamic response law of structure and site，and compares it with ABAQUS numerical simulation. The Kelvin constitutive model subroutine is introduced into the numerical model，and the equivalent linear method is used to deal with the nonlinear problem of sand in the calculation process. The experimental results are compared with the numerical model to verify the reliability of the numerical simulation. On this basis，eight working conditions are designed，and the interaction law between structures in the system is studied through comparative analysis. The results show that the tunnel will amplify the peak acceleration of the bridge pile and adjacent tunnel，but the bridge pile will weaken the peak acceleration of the side tunnel； the existence of the tunnel and bridge pile will increase each other's section shear force and bending moment. The main affected areas are concentrated in the upper and lower arches of the tunnel and the interface between the pile bottom of the bridge pile and the pile-soil.

To enrich the measured database of the modal parameters of the long-span cable-stayed bridge，based on the data collected by the structural health monitoring system of the Sutong Bridge，the modal parameters of the bridge during 2010 are obtained using the established automated modal identification and tracking method. On that basis，the variability of the modal parameters of the bridge with the changing temperature and wind speed is analyzed. Results show that the frequency of the bridge is controlled by both temperature and wind speed. The frequency decreases with the increased temperature and increases with the increased wind speed. The variability of the damping ratio of the main girder of the bridge is significantly greater than that of the frequency. The damping ratio of the first-order lateral bending modes of the main girder fluctuates between 0.5% and 15% at low wind speed interval. It gradually decreases and stabilizes at about 2% when the wind speed is greater than 9 m/s. The damping ratio of the first four vertical bending modes of the bridge is mainly affected by the aerodynamic damping. It increases slightly with the increase of wind speed at the low wind speed intervals. The obtained results can provide a reference for assessing the in-service performance and issuing operational management of the bridge.

In order to solve the problem of complex nonlinear vibration response in the traveling vehicle system，a nonlinear dynamical model for a coupled human-vehicle-road system with three-degree-of-freedom is established. The coupled vibration equations of human-vehicle-road with three-degree-of-freedom are derived by the Lagrange equation，and the sine and cosine functions of this system arise from the geometric nonlinearity of torsional deformation. The nonlinear restoring force surfaces，potential energy surfaces and analytical expressions of natural frequency are obtained for the free vibration of the human-vehicle-road system. For the forced vibration，the influence of vehicle system parameters of vehicle mass，moment of inertia，passenger mass，seat stiffness，suspension stiffness，damping，centroid position，road wavelength and wave amplitude on the response curves of amplitude velocity is analyzed by using the numerical simulation method. The experimental platform of the coupled human-vehicle-road vibration system is built and the reliability of theoretical analysis and numerical results is verified by the experiments. The results show that this nonlinear dynamical coupled system with three degree-of-freedom can accurately describe the human-vehicle-road response characteristics，and reasonable selection of the system parameters can effectively reduce the vibration response amplitude and improve the human riding comfort.

The construction of a new power system requires to improve the response time of pumped storage units. In this paper，taking a specific pumped-storage unit as an example，systematical research is performed on the main differences of sequence control process and the variation law of unit stability parameters under normal and fast pumping to generating mode. Based on that，the inverse-time vibration evaluation method is introduced to evaluate the impact of transition modes on the unit vibration peak-to-peak values. By analyzing the pressure fluctuation in the vaneless zone with the frequency spectrum analysis method，the phenomenon of hydraulic resonance in the vaneless region at low speed is found in generating rotation，and the correlation between resonance amplitude，frequency and speed is revealed. The research indicates that the mode transition from pumping to generate the fast transition is better than the normal transition. Compared with the braking method of electrical brake plus mechanical brake in normal transition，the hydraulic braking mode under fast transition can significantly shorten the transition time from 438 s to 220 s. From the perspective of vibration damage to the unit，13 of the 14 vibration and runout monitoring points prove that fast transition is conducive to prolong the expected life of the unit. Meanwhile，the fast transition is favorable to pass the hydraulic resonance occurring in vaneless zone at low speed. The hydraulic resonance time is reduced from 15 s in normal transition to 5 s in the fast transition，and the resonance speed range is compressed by more than 60%.

The constant erosion of ocean waves seriously affects the safe operation and service performance of ocean engineering equipment，and ocean wave energy is a green renewable energy with many advantages. How to reduce the wave load and utilize the ocean wave energy through the hybrid wave attenuation and energy harvesting structure is one of basic scientific problems in the field of ocean engineering. The traditional wave attenuation and energy harvesting structure，especially the floating structures in the deep sea，has the technical bottleneck of wave attenuation and energy harvesting at a low frequency range. In this paper，based on the idea of reducing the equivalent dynamic stiffness of the system，a nonlinear hybrid wave attenuation and energy harvesting structure is proposed，and the characteristics are studied. A new type of negative stiffness mechanism is designed and applied to hybrid wave attenuation and energy harvesting structure. In order to solve the fluid-structure interaction problem of nonlinear hybrid wave attenuation and energy harvesting structure，a semi-analytical nonlinear frequency domain method of hybrid eigenfunction expansion matching method and multi-harmonic balance method is proposed. The influence of the key parameters of the mechanism on the wave attenuation and energy harvesting performance is studied，and the “phase control” mechanism of the negative stiffness mechanism to improve the low frequency wave attenuation and energy harvesting performance is revealed.