美国世贸中心WTC7次梁-柱节点高温下的破坏行为分析  

ANALYSIS OF BEHAVIOUR OF SECONDARY BEAM-COLUMN CONNECTIONS OF WTC7 AT HIGH TEMPERATURE

作　　者：余红霞[1] 刘涛[2] 

机构地区：[1]清华大学,北京100084 [2]江苏沪宁钢机股份有限公司,江苏宜兴214231

出　　处：《钢结构》2010年第8期76-82,共7页Steel Construction

基　　金：留学回国人员启动基金(20091021043)

摘　　要：对美国世贸中心WTC7中采用的4种次梁-柱的钢节点建立了H型框架的有限元分析模型,模型中考虑了高层结构中常见的单根组合梁两端受到钢柱或者剪力墙等强约束的情况,对框架在自然火灾升温条件下的行为进行了分析。分析结果表明:节点是框架结构中的薄弱环节,节点的破坏往往发生在较早的阶段。比较了节点类型与特性对梁的挠度、沿梁轴向的约束力以及节点弯矩的影响,发现抗弯刚度较大的节点会产生较小的挠度和非常大的轴向约束力。对各种节点类型的破坏形式的分析发现,节点的破坏不是由于自身的强度降低,而是主要由于梁的削弱导致弯矩被转移到节点区域。如果轴向压力不对节点的受压区产生灾难性的影响,节点的破坏都发生在受拉区。因此,热膨胀引起的约束压力能减小受拉区的受力,延迟节点的破坏。A finite element analysis model was built to simulate the four types of secondary beam-column connections in WTC7.A ＂H＂ shaped sub-frame was adopted to consider the typical connection in a high-rise building,in which the beam was subjected to strong restraint from the external column or the internal core,and a natural fire exposure was considered.The analysis shows that connections are the weak link in such frames and they tend to fail at an early phase of heating.A comparison of the beam deflection,beam axial force and the connection moment is carried out when different connection types are used.The result shows that stiffened connections help to reduce the beam deflection,but cause very high axial force in the beam and very large bending moment in the connection.An analysis of the failure modes of the connections shows that connection failure was not caused by the degradation of the connection strength,but because of the moment transferred from the beam mid-span as a result of the beam weakening.If no devastating damage was caused to the compression zone by the beam axial force,the connections always fail in the tension zone.As a consequence,the beam axial force generated due to the restraint to the thermal expansion can decrease the force in the tension zone and delay the connection failure.

关 键 词：节点 高温 破坏 有限元分析 WTC7 

分 类 号：TU391[建筑科学—结构工程]