高烈度震区大跨径中承式钢箱系杆拱桥减隔震技术研究

Analysis and optimization of seismic mitigation and isolation effects for long span steel box tied arch bridges in high intensity seismic regions

为了研究高强度地震作用下大跨径中承式钢箱系杆拱桥地震响应及减隔震技术,以西双版纳黎明大桥为工程背景,选取类似场地的实际地震动记录作为输入地震波,采用非线性时程分析法,研究支座类型及参数变化对拱桥结构的减隔震效果。结果表明:相比于普通支座,减隔震支座能大幅降低结构内力,但纵向位移有所增加,且摩擦摆支座的减隔震效果要强于铅芯橡胶支座;摩擦摆支座+黏滞阻尼器联合抗震体系能够有效降低纵向和横向位移,进一步能提升桥梁的抗震性能;对联合抗震体系进行参数敏感性分析可知:最佳的参数范围是:摩擦因数为0.04,曲率半径在3 200~4 200 mm,阻尼系数为6 000,阻尼指数在0.2~0.4;在最优抗震体系下,结构位移和内力均显著降低,最大减震率分别达到了75.3%和82.3%,表明该体系大幅提高了拱桥抵抗地震的能力,为同类桥梁减隔震设计提供参考。

In order to study the seismic response and seismic isolation technology of long-span half-through steel box tied arch bridges under high-intensity earthquake,taking Xishuangbanna Liming Bridge as the engineering background,the actual ground motion records of similar sites were selected as input seismic waves,and the nonlinear time history analysis method was used to study the seismic isolation effect of different bearing type and parameter change on arch bridge structures.The results show that compared with the ordinary bearing,the seismic isolation bearing can greatly reduce the internal force of the structure,but the longitudinal displacement increases,and the seismic isolation effect of the friction pendulum bearing is stronger than that of the lead rubber bearing.The combined seismic system consisting of friction pendulum bearing and viscous damper can effectively reduce the longitudinal and transverse displacements,and further improve the seismic performance of the bridge.The parameter sensitivity analysis of the combined seismic system shows that the optimal parameter range is:the friction coefficient is 0.04,the radius of curvature is between 3200 mm and 4200 mm,the damping coefficient is 6000,and the damping index is between 0.2 and 0.4.As for the optimal seismic system,the structural displacement and internal force are significantly reduced,and the maximum seismic reduction rates are 75.3% and 82.3%,respectively,indicating that the system greatly enhances the ability of the arch bridge to resist dangerous earthquakes,which will undoubtedly provide a case for the seismic isolation design of similar bridges.