基于纤维模型的钢框架连续倒塌抗力机制分析

Analytical Investigation of Progressive Collapse Resistance Mechanism in Steel Moment Frame with Fiber Model

利用基于纤维模型的梁柱单元建立了框架结构的连续倒塌分析模型。基于Pushdown分析方法,开展了不同破坏工况下的连续倒塌分析,研究局部破坏后剩余结构的连续倒塌抗力机制。分析结果表明,破坏位置不同,剩余结构的抗倒塌机制也不同。在中柱破坏的工况下,剩余结构具备由抗弯机制与悬链线机制提供的抗倒塌承载能力,并且在失效跨内仅有底部第1、第2层梁演化出悬链线效应机制并提供竖向抗倒塌承载力,其余梁体在抗弯机制失效后,未演化出悬链线效应机制。在边柱破坏的工况下,剩余结构仅具备由抗弯机制提供的抗倒塌承载能力,失效跨内梁体均未演化出悬链线效应机制。

An advanced finite element model was presented based on fiber beam-column element.In order to investigate the resistance mechanism of steel frame structure subjected to progressive collapse,non-linear static Pushdown analysis was carried out in two cases.The center column was removed in one case while the boundary column collapsed in the other.Analytical results show that the residual structure has different resistance mechanism in the two cases.In the case of middle column removal,bending resistance and catenary action resistance offer the anti-collapse capability of the residual frame structure,and catenary action effect is developed only in the first and second floor beams in the damaged bay,other beams do not form the catenary action.In the boundary column removed case,only bending resistance provides resistance capacity to the remaining beams,catenary action cannot form in any beams in damaged bay.