近断层地震速度脉冲对层间隔震结构响应影响的振动台试验研究

Shaking Table Tests on Effect of Near-fault Ground Motion Velocity Pulse on Seismic Responses of Story Isolation Structure

近断层地震动向前方向性效应和滑冲效应引起的两种速度脉冲运动,对隔震结构动力响应的影响不同。选取含有向前方向性效应速度脉冲、滑冲效应速度脉冲、无速度脉冲的近断层地震波作为地震动输入,对一个5层钢框架层间隔震结构模型进行模拟地震振动台试验。结果表明,层间隔震结构在含脉冲近断层地震作用下的动力响应,明显大于无脉冲近断层地震;向前方向性效应与滑冲效应对结构地震响应的影响与结构周期相关,对于中短周期结构,向前方向性效应相对滑冲效应引起的结构响应更大,对于长周期结构,则相反;层间隔震技术能有效地减小结构地震响应,隔震层上部结构的减震率大于下部结构,减震效果随着隔震层位置的升高而降低。

The seismic responses of 5-story structure with different isolation story is studied under the action of two types of near-fault ground motions with different velocity pulses due to forward directivity and fling step effects.The shaking table tests of a 5-story steel frame isolated structure model are completed.Near-fault ground motions with forward directivity velocity pulse,fling-step effects velocity pulse and without velocity pulse are selected as seismic inputs.The research indicates that the seismic responses of multi-story structures with different isolation stories under the near-fault ground motions are significantly larger than that without the near-fault ground motions.The seismic responses of the structure under forward directivity effect and fling step effect of ground motions are period dependent,and for the short and medium period structures,the forward directivity effect is larger than the fling step effect.For the longperiod structures,the reaction laws are opposite.Seismic isolation technique can effectively reduce the seismic response of the structure.The seismic ratio of the upper structure of the isolation layer is larger than that of the lower structure;The seismic effect decreases with the rise of the isolation layer.