Study Of Control For Seismic Damage Modes Of Cable-Stayed Bridge With Multi-Tower

Human is imperiled by earthquake which is one of the most dangerous disasters in all ages. Several large earthquakes happened in recent years implied that much troubles were brought due to the damage of bridges. It is more difficult to rescuer the victims for the breakage of lifeline structures and increase the secondary damage largely. Cable-stayed bridges are one of types of long-span bridges and play an important role in lifeline engineering, this means the research of dynamic oscillation of cable-stayed bridges is more significant. Following the foundation of benchmark mode of cable-stayed bridge, the research relate to the vibration control based on benchmark model were arisen.In this dissertation, the Shandong Binzhou Yellow River Highway Bridge is employed on OpenSees to study the seismic damage and control of long span cable-stayed bridge. The main research contents are as follow.First, the seismic performance of rigid system (RS), floating system (FS) and passive energy dissipation system (PEDS) under two different earthquake records are studied and the effect of near-fault ground motion is gotten. The failure modes of different systems of cable-stayed bridge are investigated by Park and Ang seismic damage model.Second, the relationship between bridge damping ratio and damper stiffness is deduced for a simplified cable-stayed bridge model. The maximum damping ratio of the cable-stayed bridge presents when the optimum damper stiffness reaches. It is found that the optimum damper stiffness is negative. The nonlinear seismic behavior of the cable-stayed bridge with the damper is studied through numerical simulations. The reduction in seismic response of the cable-stayed bridge incorporated with negative stiffness dampers is demonstrated. The influence of stiffness of dampers on the seismic behavior of cable-stayed bridges is further investigated. The results indicate that the seismic performances of the cable-stayed bridge are perfect and the damping ratio of the bridge achieves its maximum value when damper stiffness is optimum. The seismic performance of the bridge incorporated with nonlinear viscous damper coupled with negative stiffness is also analyzed through numerical example. The results indicate that the seismic behavior can be further improved with the increasing of velocity exponent.Third, Shape memory alloys (SMA) materials are added into material library in OpenSees. A SMA damper with special configuration, which guarantee the SMA wires in damper being elongation regardless of motion direction, is proposed and incorporated into the bridge between the deck and tower. A parametric analysis of seismic response of the bridge with SMA damper under near-fault earthquake ground motion is conducted. Furthermore, the seismic response and failure modes of the cable-stayed bridge with three kinds of connecting configurations are investigated and compared with each other. The effects of SMA damper on the reduction of maximum seismic response and the control of residual deformation are verified. The influence of damper stiffness, different ground motions and PGA on the control of residual deformation using SMA damper is analysized. The difference between SMA damper and SMA incorporate with frictional damper in the control of cable-stayed bridge is studied.Fourth, the influence of soil-pile-superstructure-interaction on seismic performance of cable-stayed bridge is investigated by numerical simulation. Then the effectiveness of dampers to reduce the seismic response of cable-stayed bridge with SPSI is studied, and the conclusion reveals that SPSI will reduce the effectiveness of damper.Finally, the common pushover method is introduced to cable-stayed bridge, and the distribution of lateral force according to first model of tower is deduced. The proportion of lateral force between middle tower and side tower is equal to the proportion between tower horizontal stiffness. Using the deduced distribution of lateral force, the failure modes of three systems of cable-stayed bridge are gotten and the method is proved to be feasible by comparing with the time-history analysis.