Optimization of Arrangement and Parameters of Viscous Dampers for Cable-stayed Bridge with Semi-floating System

In order to solve the problem of optimization of viscous dampers for a new-built cable-stayed bridge with semi-floating system, the SAP2000 was used to establish a three-dimension finite element model of the bridge. Based on the energy dissipation principle of the viscous damper and the seismic capacities of the critical elements of the bridge, different arrangements of dampers in both longitudinal and transverse directions were compared and the performance parameters of damper were optimized for the transverse direction. The results show that without viscous dampers the bridge is a semi-floating system in the longitudinal direction and the inertial force of the girder is mainly transferred to the pylon, which leads to damage to the pylon. The seismic response of the auxiliary and transitional piers is relatively small, but the deformation of the bearings on the piers is large enough to exceed their limits. The inertial force of the girder in the transverse direction is resisted by both the pylon and the transitional piers, with little resistance provided by the auxiliary piers since sliding bearings are mounted on the auxiliary piers in both directions. And therefore the transitional piers suffer damage in the transverse direction. When 4 dampers are arranged between the pylon and the girder in the longitudinal direction, the pylon will remain sound and the bearings will deform within their limits. When the bearings on the transitional piers are replaced by sliding bearings and dampers are installed beside the bearings in the transverse direction, the transitional piers will be protected from damage and the bearings will be prevented from excessive deformation. And optimization analysis reveal that the reasonable performance parameters for dampers are ξ=0.3 and C=3 000 kN/(m/s) ^ξ.