近断层速度脉冲向前方向性效应和滑冲效应对巨-子结构体系地震反应的影响

Effects of forward directivity and fling-step of near-fault velocity pulse on seismic response of mega-sub structural system

建立巨-子结构抗震体系和隔震体系计算模型,选取向前方向性效应和滑冲效应引起的两类速度脉冲型实际地震动记录,并分别拟合具有相同加速度谱而无速度脉冲的人工地震动时程作为输入,探讨了在有、无速度脉冲地震动下两种不同巨-子结构体系的地震位移反应,详细分析了两类不同产生机制的速度脉冲型地震动对巨-子结构体系位移反应的影响差异.结果表明:近断层速度脉冲地震动对巨-子抗震结构的位移反应影响较小,但会使巨-子隔震结构的位移反应显著增大;滑冲效应对巨-子隔震结构主结构位移影响更大,向前方向性效应对巨-子隔震结构的隔震层位移影响更大;不同产生机制的速度脉冲对巨-子结构体系不同部位的位移反应影响存在差异,应分别考虑设计重点.

In this paper,the calculation model of seismic structure and isolation system of mega-sub structural system is established.Then we select two types of actual ground motion records of velocity pulse type caused by forward directivity effect and fling-step effect,and fit the artificial ground motion time history with the same acceleration spectrum but without velocity pulse.Using these ground motions as inputs,the seismic displacement responses of two different giant-substructure systems under the presence and absence of velocity pulse ground motions are discussed.We analyze in detail the differences in the responses of two types of velocity-pulse ground motions with different generation mechanisms to the displacement of mega-sub structural system.The results show that the near-fault velocity pulse ground motion has a small effect on the displacement response of the mega-sub structural seismic system,but it will significantly increase the displacement response of the mega-sub structural isolation system.Fling-step effect has a greater effect on the displacement of the main structure of the mega-sub structural isolation system,and forward direction effect has a greater effect on the displacement of the isolated layer of the mega-sub structural isolation system.The effects of velocity pulse ground motions are different,with different generation mechanisms on the displacement response of different parts of the mega-sub structural system,and key designs should be considered separately.