大跨双层斜拉桥地震响应控制

以目前跨度最大的双层公路斜拉桥——闵浦大桥为例,基于Abaqus平台建立非线性动力分析模型,研究了非线性粘滞阻尼器、弹性/非弹性连接对该桥地震响应的减震控制效果.多组非线性时程分析研究表明:塔梁间的非线性粘滞阻尼器增大了下塔柱纵桥向弯矩和剪力,对上塔柱影响较小;阻尼指数一定的情况下,塔底纵桥向剪力和弯矩随阻尼系数的增加而增大.由于大跨斜拉桥的振动模态具有密集、低周期的特点,因而其地震响应受地震输入的影响较大;塔梁间增加弹性/非弹性连接会影响桥梁的纵漂振型,进而影响结构的地震响应,因此塔梁间增加弹性/非弹性连接的减震效果取决于输入地震特性以及塔梁间增加弹性/非弹性连接后的动力特性.文中提出采用非弹性连接参数的联合分布以分析其对地震响应的影响,非弹性的初始刚度和屈服位移联合作用对主梁地震响应的影响较为复杂,文中研究表明,其屈服位移对桥梁地震响应的影响较为明显.

Seismic Response Control of Double-deck Long-span Cable-stayed Bridges

The influence of nonlinear viscous fluid damper,elastic connection and inelastic connection between tower and gird or between piers and gird were investigated in this study.Shang hai Minpu Bridge was taken as an example and its finite element model was established based on Abaqus.Several groups of nonlinear time-history analysis were carried out and the results showed that nonlinear viscous fluid dampers caused the increase of moment and shear of lower tower column in longitudinal direction and had little influence on upper tower column.Moment and shear in longitudinal direction at the bottom of tower increase with the damping coefficient when the damping exponent was set to constant.Long-span cable-stayed bridges generally have dense and low-period modes,therefore the seismic response of long-span cable-stayed bridges are sensitive to the excitation motions.Elastic or inelastic connections between gird and tower alter the longitudinal drift mode of gird and influence the seismic response of the bridge.The effect of elastic or inelastic connections on the seismic mitigation depends on the earthquake motion inputted and the dynamic characteristics of bridge after above connections are installed.Joint distributions of inelastic connection parameters were presented to discuss their influence on the seismic response of key components.The effects of initial stiffness and yield displacement of inelastic connection are complicated.In contrast,the influence of the yield displacement on the seismic response is relatively more obvious than the initial stiffness.