山地典型掉层框架结构抗连续倒塌性能分析

Analysis on progressive collapse resistant capacity of typical mountainous step-terrace frame structures

山地结构的受力性能与普通结构有显著差别。基于LS-DYNA的截面纤维模型,通过与一榀4跨3层平面框架在移除中柱后的拟静力倒塌试验结果进行对比,验证了纤维模型的合理性。采用拆除构件法中的非线性动力法对普通框架结构和掉层层数、掉层跨数各不相同的掉层框架结构共6个算例进行了抗连续倒塌性能分析,研究普通框架结构与掉层框架结构抗连续倒塌性能的差异以及掉层层数、掉层跨数对掉层框架结构抗连续倒塌能力的影响。结果表明:悬链线效应对于RC框架结构抗连续倒塌性能有显著的提升作用;掉层框架结构上、下接地层的抗连续倒塌性能差异大;下接地层区域,掉层框架结构抗连续倒塌性能低于普通框架结构,上接地层区域则相反;随掉层层数增加,掉层框架结构抗连续倒塌性能减弱;随掉层跨数增加,掉层框架结构抗连续倒塌性能增强。

The mechanical properties of mountainous structures are significantly different from those of ordinary structures. Based on the LS-DYNA fiber model, the rationality of the fiber model was verified by comparing with the quasi-static collapse test results of a 4-span 3-story plane frame after removing the central column.The nonlinear dynamic method of the alternative path method was used to analyze the progressive collapse resistance of six examples of ordinary frame structure and step-terrace frame structure with different number of dropped story and dropped span. The difference of progressive collapse resistance between ordinary frame structure and step-terrace frame structure and the influence of dropped stories and dropped spans on the progressive collapse resistance of step-terrace frame structure were studied. The results show that the catenary action can significantly improve the progressive collapse capacity of RC frame structures. The progressive collapse resistance of the dropped part and upper part of the step-terrace frame structure is different, and the progressive collapse resistance of the dropped part is lower than that of the ordinary frame structure, but the upper part is on the contrary. With the increase of the number of dropped story, the progressive collapse resistance of the step-terrace frame structure decreases, with the increase of the number of dropped span, the progressive collapse resistance of the step-terrace frame structure increases.