基础隔震山地掉层框架结构抗连续倒塌性能研究

山地隔震结构本身具有特殊性,因此其破坏模式、受力性能与普通平地隔震结构体系有很大的不同.为了研究基础隔震山地掉层结构的抗连续倒塌性能,首先对一榀4跨3层平面框架拟静力试验进行数值模拟并验证了LSDYNA纤维单元模型的可靠性,根据中国规范设计了6个基础隔震掉层体系框架和1个普通平地隔震结构,基于拆除构件法对剩余结构进行抗倒塌性能研究,得到其荷载系数与失效点竖向位移曲线.研究结果表明,拆除下接地角柱(支座)、上接地角柱时,平地隔震结构的抗倒塌能力大于掉层隔震结构;拆除上接地支座时,平地隔震结构的抗倒塌能力弱于掉层隔震结构;隔震山地掉层框架结构邻近坎下边支座(底层柱)失效跨的抗力机制要滞后于上接地跨的抗力机制,可为基础隔震山地掉层框架结构的抗连续性倒塌设计提供参考.

Study on the progressive collapse of the base-isolated mountain step-terrace structure

In order to study the anti-progressive collapse performance of the base-isolated step-terrace structure, a 4-span 3-story plane frame was simulated to verify the reliability of the LSDYNA computing platform. Then, in compliance with the national specifications, six basic isolation and step-terrace system frames and one ordinary flat isolation structure were designed, and the collapse resistance of the remaining structure was studied based on the demolition method to obtain the load coefficient and the vertical displacement curve of the failure point. The results show that when the lower grounded corner column(support) and the upper grounded corner column were removed, the anti-collapse ability of the flat ground isolation structure was greater than that of the base-isolated step-terrace structure; when the upper ground support was removed, the anti-collapse ability of the flat ground isolation structure was weaker than base-isolated step-terrace structure. Furthermore, the resistance mechanism of the failure span of the bottom support(bottom column) adjacent to the sill lagged behind the resistance mechanism of the upper ground span. Our study provides reference for the anti-progressive collapse design of the base-isolated step-terrace structure.