典型山地建筑掉层框架结构抗震性能Pushover分析

Seismic performance of step-terrace structure by Pushover method

针对山地掉层结构在不同加载方式下的抗震性能,基于Pushover方法,分析了不同掉层层数和掉层跨数对掉层结构的影响以及掉层结构和平地结构抗震性能的区别;进一步针对掉层结构和平地结构,研究了Pushover分析结果与非线性动力时程分析结果的相关性,以及不同侧向加载模式下Pushover分析方法的适用性。结果表明:掉层层数和掉层跨数对掉层结构的抗震性能影响较大。掉层结构的掉层部分相比坎上部分破坏较轻,坎上1~3层梁端和上接地柱的塑性破坏最严重;随着掉层数和掉跨数的增加,坎上1层接地柱及与其相连的梁将在结构其它部位的梁柱端塑性未能充分发展前失去承载能力,使得结构达到推覆极限状态。掉层结构Pushover分析方法和时程分析方法的结果趋于一致,说明采用Pushover分析方法对掉层结构进行抗震性能评估是可行的。倒三角加载和指数加载模式会低估掉层部分的地震反应,对于掉层部分进行抗震性能评估时,宜采用均匀加载和MPA方法。

Based on the Pushover method,the seismic performance of step-terrace mountain frame structure with different numbers of the off-layer and the off-across under different loading modes was analyzed,the difference of seismic performance between the step-terrace mountain structure and the normal structure was discussed. The correlation of analysis results of Pushover and nonlinear dynamic time-history method and the applicability of the Pushover analysis method under different lateral loading modes were studied. The results show that the numbers of the dropped story and the dropped bays have great influence on the structure. The damage of the dropped story is lighter than the upper structure,and the most serious damages appear in the beam-ends of the 1-3 stories of the upper structure and the upper grounding columns. As the numbers of the dropped story and the dropped bay increase,the grounding column of the first story will be damaged prematurely,and the limit state is reached. The results of Pushover analysis method and time history analysis method are consistent. It is feasible to evaluate the seismic performance of the step-terrace structure by the Pushover method,without considering the effects of the higher modes in the Pushover analysis. Inverted triangular loading and exponential loading pattern may underestimate the seismic response of the dropped stories,but the uniform distribution pattern and the MPA method can make a well evaluation of seismic performance of the dropped stories.