地震作用下全浮漂大跨斜拉桥耗能减震控制研究

Energy dissipation control for long span cable-stayed bridges as a full-floating system under earthquake

以某实际全浮漂大跨斜拉桥为研究应用对象,探讨了全浮漂大跨斜拉桥阻尼器的布置原则,考虑桩-土的相互作用,建立了全桥空间有限元分析模型,针对该非比例阻尼体系,通过基于应变能理论的振型阻尼分别考虑上部结构阻尼、下部结构阻尼和阻尼器阻尼,从而实现结构不同部分不同阻尼引入到有限元分析模型。然后进行了黏滞阻尼器参数优化,得到了最优阻尼系数和最优阻尼速度指数,并进行减震效果分析。研究结果表明:采用黏滞阻尼器可有效控制结构的地震响应,主塔顶位移、主梁位移和主塔底弯矩分别减小为普通全浮漂体系的60.4%、56.7%、71.8%;随着阻尼系数增加和阻尼速度指数的减小,梁端位移、塔顶位移和阻尼器位移减小,主塔墩底弯矩单调减少,当阻尼系数增加和阻尼速度指数的减小到一定值时主塔墩底弯矩控制效果基本稳定。

The arrangement principle of dampers for long span cable-stayed bridges as a full-floating system was discussed based on one actual long span cable-stayed bridge and considering pile-soil interaction,its spatial finite element model was built.Based on modal dampings in the strain energy theory,the dampings of superstructure,substructure and dampers were considered,so different dampings of different components were induced in the FE model of the bridge. Then,the parametric optimization of fluid viscous dampers was performed.The optimal damping velocity index and the optimal damping coefficient were obtained.Furthermore,the effect of energy dissipation on the seismic response of the bridge under earthquake was analyzed.The results showed that the top displacement of the main tower,the displacement of girder,and the bending moment at the bottom of the main tower of the bridge with viscous dampers decrease to 60.4%, 56.7%,and 71.8% of those of an ordinary bridge as a full-floating system,respectively;with increase in damping coefficient and decrease in damping velocity index,the displacements of girder,the main tower and dampers decrease and the bending moment at the bottom of the main tower monotonously decreases;the control effect on the bending moment at the bottom of the main tower is basically stable when increase in damping coefficient and decrease in damping velocity index reach certain values.