轴向与截面非均匀温度场对某固支钢梁最大挠度的影响

Effect of non-uniform longitudinal and transverse temperature distributions on maximum deflection of a fixed supported steel beam

目前钢构件火灾响应特性的数值模拟分析一般假设温度场轴向均匀分布,但大空间真实火灾环境下,火源位置的变化往往会导致温度场轴向和截面的非均匀。采用ANSYS有限元分析软件,对某12m长固支钢梁在三面受火情况下的最大挠度进行分析,首先假设温度场轴向非均匀分布,在此基础上进一步假设截面方向也存在非均匀分布,并与轴向均匀温度场下钢梁的最大挠度进行比较。在该文研究条件下可得如下结果:钢梁在轴向非均匀温度场下最大挠度较小,耐火时间增长;对于温度场轴向非均匀分布,截面同时非均匀分布时钢梁最大挠度较大;当温度场轴向非均匀、截面均匀时,火源位置从端部到中间,钢梁最大挠度逐渐减小,在距端部1/4处最大挠度有突增。

Currently,uniform temperature distributions are widely assumed in numerical simulations when analyzing the fire response characteristics of steel structure,but in real large space fires,non-uniform longitudinal and transverse temperature distributions are usually present.In this paper,the maximum deflection of a 12m fixed supported steel beam with three aspects surrounding fires is analyzed by finite element analysis software ANSYS.It is first assumed that the longitudinal and transverse temperature distributions are both non-uniform.Such case is compared to that with uniform longitudinal temperature distributions.Under the conditions in this paper,it is concluded that the maximum deflection is smaller with non-uniform longitudinal temperature distributions,i.e.the fire resistant time is longer;for non-uniform longitudinal temperature distributions,the deflection of steel beam is higher with non-uniform transverse temperature distributions;for non-uniform longitudinal and uniform transverse temperature distributions,the maximum deflection decreases with the fire location ranging from the end to the middle,but it has an abrupt increase at 1/4 location from the end.