半漂浮体系斜拉桥粘滞阻尼器布置与参数优化

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

针对某新建半漂浮体系斜拉桥的阻尼器优化布置问题,采用SAP2000建立了全桥三维有限元模型,基于粘滞阻尼器耗能原理,以桥梁关键部位的抗震能力为指标,对比研究纵、横桥向不同阻尼器布置方式的减震效果,并对横桥向阻尼器的性能参数进行优化。研究表明:当不设置阻尼器时,主梁在纵桥向为半漂浮体系,其惯性力基本由索塔承担,导致索塔出现损伤,辅助墩和过渡墩尽管内力较小,但其支座变形超限;主梁横向惯性力主要由索塔和过渡墩承担,辅助墩由于布置双向支座参与很小,由此导致过渡墩损伤。在纵桥向,在塔梁交接处布置4个阻尼器时,索塔可保持无损状态,支座变形也低于容许值;在横桥向,将过渡墩单向支座改为双向,并布置双侧阻尼器后,可保证过渡墩处于无损状态,且支座变形低于容许值,此时的优化参数为ξ=0. 3、C=3 000 k N/(m/s)~ξ。

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.