具有软着陆保护的橡胶支座隔震体系

Rubber Bearing Isolation System with Soft Landing Protection

文中提出了一种由承载橡胶支座和一端具有摩擦滑动面的后备支座组成的并联隔震体系，用以防止承载橡胶支座发生大变形失稳破坏，充分发挥其剪切变形能力，从而达到既经济又安全的抗震设计。体系中的后备支座可以在上部结构施工完毕以后再进行安装，并应保证其在正常使用状态下基本不受竖向荷载。当发生强烈地震时，随着承载支座发生较大的水平向变形并出现下沉的倾向，轴压力逐渐从承载支座转移到后备支座上，后备支座的摩擦面出现滑动，由于滑动面上的力是随轴压力增大而增大的，因此后备支座实际上是一个具有变摩擦滑动特性的软着陆机构，它不仅保护了承载支座免遭大变形失稳破坏，同时还能提供摩擦阻尼，在限制隔震层的位移方面发挥良好的作用。文中对这种并联隔震体系的力学特性和分析计算方法进行了详细的讨论，并用实例展示了在发生水平向大变形条件下，轴压力从承载支座向后备支座上转移的情况。

Aiming at economic and safe seismic design,a kind of parallel isolation system is presented in this paper, which is composed of loaded rubber bearings and back up supports with a top friction sliding surface. The instable failure of the rubber bearings at large horizontal displacement is averted and their shearing deformation capability will be fully exerted. When strong earthquake happens, the loaded rubber bearings will yield vertical deformation and sinking.Then the superstructure will move over top friction sliding surface of the back up supports with the result that the vertical pressure gradually shifts from the loaded bearings to the back up supports. Since the friction force on the sliding surface of the back up support will increase as its vertical pressure increases, the back up support, which is actually a varying friction sliding load bearing device, will not only prevents the loaded bearing from instable failure caused by large deformation but also provides friction damping and exerts better effect with respect of reducing horizontal displacement of the isolation layer. This paper discusses the mechanism and the analysis methodology of the parallel isolation system in detail and illustrates features of the axial pressure conveying from the loaded rubber bearings to the back up supports.