基于增量动力分析法的多柱失效钢框架连续倒塌研究

Study of progressive collapse of steel frames with multi-column failed based on incremental dynamic analysis method

针对连续倒塌研究中单构件失效与实际偶然荷载造成多构件失效不符这一问题,建立11个数值模型。考虑楼板影响,采用增量动力分析法(IDA),研究多柱失效后剩余结构抗连续倒塌能力、失效机理和抗力计算,并与单柱失效进行对比。结果表明,多柱失效时,模型1在β≤1、模型2~6在β≤2时处于小变形阶段,由梁机制和空腹作用抵抗连续倒塌;大变形阶段时由悬链线机制和空腹作用抵抗连续倒塌。模型7~9在β≤2时处于小变形阶段,β继续增大无法形成有效悬链线机制,结构抗力由梁机制和空腹作用提供。单柱失效时,模型10和模型11在β≤3时处于小变形阶段,发生连续倒塌时最大β分别为4.8和5.4,单柱失效时结构抗倒塌能力大于多柱失效。随β值增大,多柱失效结构位移响应更敏感。CRS(column removal span)梁两侧框架侧向刚度不同会导致结构发生非对称破坏。同时分析模型1~6和模型7~9的CRS梁破坏机理,并总结多柱失效时梁机制、悬链线机制以及空腹作用的计算公式。

Aiming at the problem that the failure of a single component does not match the failure of multiple components caused by the actual explosion in the progressive collapse study,11 numerical models were established.Considering the influence of the floor,the incremental dynamic analysis method(IDA)was used to study the progressive collapse resistance,failure mechanism,and resistance calculations of the remaining structure after the failure of multiple columns,and compared with single column failure.The results show that when multi-column fail,model 1 is in the small deformation stage whenβ≤1,and models 2 to 6 are in the small deformation stage whenβ≤2,and the progressive collapse is resisted by the beam mechanism and the emptying action.In the large deformation stage,the catenary mechanism and emptying action resists progressive collapse.Models 7 to 9 are in the small deformation stage whenβ≤2,and the catenary mechanism cannot be formed whenβcontinues to increase,and the structural resistance is provided by the beam mechanism and the emptying action.When a single column fails,model 10 and model 11 are in a small deformation stage whenβ≤3,and the maximumβis 4.8 and 5.4 respectively when progressive collapse occurs,and the collapse resistance capacity of structure when single column fails is greater than that of multi-column fail.As the value ofβincreases,the displacement response of the multi-column failure structure is more sensitive.The different lateral stiffness of the frame on both sides of CRS(column removal span)beam will lead to asymmetric failure of the structure.At the same time,the failure mechanisms of CRS beam from model 1 to model 6 and model 7 to model 9 were analyzed respectively,and the calculation formulas of beam mechanism,catenary mechanism and emptying effect when multiple columns fail were summarized.