双跨框支墙梁的抗火性能研究

Fire resistance of double span frame wall beam

采用大型通用非线性有限元软件ABAQUS6.14对双跨框支墙梁砌体结构的底框进行了受火数值分析,对其底部砌体墙荷载分布、托梁端部剪力、跨中轴力及受力机理进行研究。数值计算结果表明,达到承载力耐火极限时,考虑墙梁组合作用的托梁剪力系数均大于《砌体结构设计规范》(GB 50003—2011)中的值,且中间支座处两端的托梁剪力大小基本相等;在火灾温度场作用下,托梁轴力由拉到压再到拉的受力过程,达到承载力耐火极限时,托梁跨中轴拉力约为初始受火的二分之一。根据框支墙梁砌体结构的破坏机理,提出采用托梁跨中挠度-受火时间曲线判定墙梁组合受力的耐火极限,边转换柱端部侧向位移-受火时间曲线判定框支托梁承载力的耐火极限。

The large-scale general nonlinear finite element software ABAQUS6.14 is used to analyze the fire value of the double-pan frame wall beam.The load distribution of the bottom masonry wall,the mid-shear force,and the axle force at the end of the support beam and stress mechanisms are studied.The numerical calculation results show that:when the fire resistance limit of the bearing capacity is reached,considering the combination effect Of the wall beam,the shear coefficient of the joist is larger than the value in the Code for design of Masonry Structure,and the beam shear at both ends of the middle bearing is basically equal;under the action of the fire temperature field,the axial force of the joist is pulled from the pressure and then to the pulling force,and when the fire resistance of the bearing capacity is reached,the joist pull force of the joist is about one half of the initial fire.According to the failure mechanism of frame wall beam masonry structures,the fire resistance limit of wall-beam combination is obtained by the mid-span deflexion-fire time curve,while the fire resistance limit of the structure is obtained by column end lateral displacement curve.