火灾下钢筋混凝土梁桥高温场形变分析

High temperature deformation of reinforcement concrete beam bridges exposed to fire

利用数值模拟程序分析了火灾高温下钢筋混凝土矩形截面简支梁任意时刻的温度场分布,研究了保护层厚度、荷载等级对火灾下的钢筋混凝土简支梁高温场时程形变的影响规律,建立了钢筋和混凝土的内力积分模型,以等比数列推导了非线性加速迭代方程。研究表明:截面温度分布与测点至梁体表面距离相关;保护层厚度对钢筋混凝土简支梁跨中挠度影响较大;火灾场钢筋混凝土简支梁跨中挠度时程曲线随荷载等级的增加呈非线性增长趋势,挠度时程曲线增大的程度随保护层厚度增加而减小;增加混凝土保护层厚度,可有效提高火灾场钢筋混凝土梁桥的耐火极限,控制其变形。

The temperature field distributions of rectangle section for RC simply supported beams exposed to the ISO834 standard fire are studied by numerical simulation program, and the influence laws of the covering layer thickness and load grades on the time-independent deformation of RC beams at high temperature are presented. Based on mechanical balance principle and influence parameters, the model of inner force integration is proposed, and the nonlinear acceleration iteration equation is deduced with geometric progression. The simulation results indicate that the covering layer thickness has a great contribution to the deflection of RC simple beams, the time-dependent curves for defleetion presents a non-linear increase tendency with the raise of load grades; and its increase degree decrease with the increase of covering layer thickness; the increment of covering layer thickness is effective to fire resistance and control of deformation for RC simple beams. 8 figs, 10 refs.