火灾下外伸端板连接的局部屈曲  

Local Buckling of Extended End-Plate Connection in Fire

作　　者：郝淑英[1] 杨秀萍[1] 姚斌[2] 

机构地区：[1]天津理工大学机械工程学院,天津300191 [2]中国科学技术大学火灾科学国家重点实验室,安徽合肥230026

出　　处：《西南交通大学学报》2008年第3期330-334,共5页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金重大国际合作研究项目(50320120156);天津市高校科技发展基金资助项目(20040505);火灾科学国家重点实验室资助项目(HZ2005-KF05)

摘　　要：为深入揭示端板及加劲肋厚度对节点在火灾下失效模式的影响,采用弹塑性理论对端板承拉区的受力状态进行了分析,得到了形成2组及1组塑性铰的条件,并用非线性有限元分析方法进行了验证.研究表明,端板较薄时,随温度升高,将在其承拉区形成2组塑性铰,产生塑性弯曲大变形,导致梁的大转动和受压翼缘严重局部屈曲;端板较厚且加劲肋较薄时,将形成1组塑性铰,加劲肋屈曲导致节点失效.火灾下节点塑性铰形成的条件与常温下相同,但破坏方式更多地表现为严重的局部屈曲.因此,应适当增大端板及加劲肋厚度,以防止或减少局部屈曲的发生,提高节点的耐火极限.In order to reveal the effects of the thicknesses of end-plate and stiffener on the failure modes of extended end-plate connection in a fire, the formation conditions of one or two groups of plastic hinges in the tension zone of end-plates were investigated based on the elastic-plastic theory and validated by using nonlinear FEM （finite element method）. The research result shows that with the increase of temperature, two groups of plastic hinges will be formed in the tension zone of an end-plate with a thin thickness, and large plastic bending deformation occurs to lead to a large rotation of the beam and severe local buckling of its bottom flange in compression. Under the condition of a thin stiffener and a thick end-plate, only one group of plastic hinges will result in the failure of the connection. The conditions will be formed, and stiffener buckling to form the plastic hinges in the connection in a fire are nearly the same as those at room temperature, but the most common failure mode in a fire is severe local buckling. Therefore, the thicknesses of end-plate and stiffener should be increased properly to avoid the buckling of stiffener and beam flange and improve the fire resistance of the connection significantly.

关 键 词：外伸端板连接 火灾 破坏模式 塑性铰 局部屈曲 

分 类 号：TU311.4[建筑科学—结构工程]