钢筋混凝土T梁火灾高温时变效应研究

Study on Time-varying Effect of Reinforced Concrete T-beam Exposed to Fire

结合国内外建筑结构火灾试验,引入开裂准测和非线性本构关系,提出了火灾下结构有限元分析思路,利用数值模拟程序分析了火灾高温下钢筋混凝土T梁截面的温度分布,研究了火灾时间、荷载比对ISO834标准火灾升温过程下钢筋混凝土T梁桥挠度的时变效应规律及开裂状况。研究表明:截面温度分布梯度宽度随高温时间由外及里逐渐扩展;火灾下钢筋混凝土T梁挠度时程曲线随时间的延伸基本上呈直线下降;挠度随荷载比的增大呈非线性增加趋势;火灾下钢筋混凝土T梁斜裂缝较腹板直裂缝易发生。

Based on fire tests for building structures at home and abroad and combining with the crack criteria and nonlinear constitutive relationship, the thought of finite element analysis is put forward. Several parameters for the fire resistance on cross section of a reinforced concrete T-beam exposed to the ISO834 standard fire are analyzed, including the fire time and the ration of load. The study indicates that the temperature distribution gradient width on section gradually expanses from outside to inside with the fire time, the time-dependent curve of deflection for the reinforced concrete T-beam exposed to fire decreases linearly with time, the deflection increases nonlinearly with the ration of load, and the oblique crack is liable to occur compared with the straight crack.