基础隔震结构竖向连续倒塌机制及影响因素研究

Vertical progressive collapse mechanism and influencing factors of base-isolated structures

主要分析了隔震结构竖向连续倒塌机制和结构不同参数对倒塌机制的影响。首先通过单榀隔震框架结构的竖向推覆试验对有限元软件Seismo Struct建立的模型进行了验证。之后利用该软件采用非线性Pushdown分析方法,对含不同楼板类型、不同隔震支座、不同抗震设计的多组有限元结构模型进行了分析和对比。分析结果表明楼板增强了梁机制作用下的抗连续倒塌承载力,而对悬链线机制下的增强取决于楼板参与宽度;随着设防烈度的提高,梁机制、悬链线机制下的抗连续倒塌承载力都有提高,但梁机制下的提高幅度更明显;与非隔震结构相比,由于隔震层约束的减弱,有些工况下结构梁机制的失效会延迟,而隔震层水平刚度的提高对隔震结构的竖向相对承载力影响不大。

The vertical progressive collapse mechanism of base-isolated structures and influences of structural parameters on the collapse mechanism were studied.Firstly,vertical pushdown tests of a single plane RC base-isolated frame were used to verify its simulation model built with the finite element software SeismoStruct.Then,SeismoStruct software and the nonlinear Pushdown analysis method were adopted to analyze and compare multi-group FE structure models with different slab types,isolation bearings and aseismic designs.The results showed that slabs enhance the progressive collapse resistance capacity of base-isolated frames with beam action mechanism;the anti-progressive collapse capacity enhancement of frames with catenary action mechanism depends on the action width of slabs;with increase in fortification intensity,the anti-progressive collapse capacity of frames under both beam action mechanism and catenary one increases,but the capability increase in frames under beam action mechanism is more obvious;compared with non-base-isolated structures,the failure of base-isolated frames under beam action mechanism can be delayed in some cases due to constraints reduction of isolation layer;while the effects of increase in isolation layer horizontal stiffness on the vertical relative load-bearing capacity of base-isolated structures are small.