【摘要】 主要研究了火灾下平面钢框架的连续性倒塌模式和机制。应用OpenSees软件,对某5跨8层平面钢框架结构模型进行数值分析,研究了荷载比、梁柱刚度比和火灾场景对结构倒塌模式的影响。结果表明,随着荷载比的增大,结构倒塌模式由侧向倾倒式倒塌变为整体下沉式倒塌;当梁柱刚度比较小时,由于梁的悬链性效应,使结构发生偏向受火开间的侧向位移直至倒塌(弱梁机制),当梁的刚度比较大时,破坏首先发生在框架底层柱,结构呈整体下沉式倒塌(强梁机制);火灾中水平和竖向分布易分别引起结构局部和整体的倒塌。更多还原

【Abstract】 This paper presents the results of a numerical study,using OpenSees,of the progressive collapse of steel frames exposed to fire.A parametric study is carried out on a 2D5-bay and8-storey steel frame to find the progressive collapse mechanism of steel frames exposed to fire and corresponding influencing factors.The factors include load ratios,stiffness ratios of beam to column and fire scenarios.The results show that different progressive collapse mechanisms can happen due to the sequence of the buckling of columns.As the load ratio increases,the collapse mechanism changes from lateral collapse to the downward collapse of the whole structure.For a small stiffness ratio,the surrounding frame drifts towards the fire due to the catenary effect of the heated beam(i.e.weak beam mechanism).While for a large stiffness ratio,the bottom columns buckle first causing the collapse of the whole frame(i.e.strong beam mechanism).The horizontally and vertically distributed fire scenarios may lead to a local and global collapse of structures,respectively.更多还原