刚性限位对基础隔震结构动力响应影响试验研究

Experimental study on influence of rigid deformation limitation on dynamic response of base isolation structures

为防止隔震层在极罕遇地震作用下出现过大变形而导致隔震设施损坏,部分隔震结构安装了钢墩或钢筋混凝土墩等刚性限位装置。为了研究刚性限位对基础隔震结构动力响应的影响,设计三层单跨钢框架基础隔震结构以及钢墩、钢筋混凝土墩、带橡胶垫层钢墩三种刚性限位器,并进行振动台试验。研究不同预留间隙时三种限位器对基础隔震结构的位移、加速度、接触力以及隔震支座竖向荷载等动力响应影响的规律。试验结果表明,刚性限位器能有效减小其隔震层位移,但也会对上部楼层产生较高大的不利响应,同时会增大隔震支座的竖向荷载,甚至使支座产生拉应力。在钢墩前设置橡胶垫层能明显减小上部结构的加速度响应,对上部结构位移响应、隔震支座竖向力及碰撞点处接触力影响不大。

Steel trusses or reinforced concrete blocks are usually installed in isolated structures as rigid deformation limiters to avoid damage to the isolation system caused by excessive isolation deformation under very rare earthquakes. To investigate the influence of rigid deformation limitation on dynamic response of the base isolation structure, a three-story single-span steel frame and three types of rigid deformation limiters including steel trusses, steel concrete blocks, steel trusses with rubber were designed, and shaking table testing was carried out. The influence laws of the three deformation limiters with different reserved gaps on structural dynamic responses, including displacement, acceleration, contact force and vertical force of isolation bearings were researched. The test results show that the rigid deformation limitation can effectively reduce the displacement of the isolation layer, but it also produces a high adverse response to the superstructures, and magnifies the vertical force of the isolation bearing, and even produces tensile stress on the bearing. The rubber cushion in front of the steel truss can obviously weaken the acceleration responses of the superstructure, and has little effect on the displacement responses of the superstructure, the vertical forces of the isolation bearings and the contact force at the contact points.