植筋连接混凝土梁耐火极限计算方法

Prediction Method on Fire Endurance of Post Installed Rebar Beams

为定量评估火灾情况下的耐火极限,提出了高温下植筋连接混凝土梁耐火极限预测方法.采用等效截面法,考虑混凝土和钢筋强度在高温下的弱化,对截面进行强度折减,等效为阶梯形截面,结合常温下构件力学性能的简化计算理论及火灾中单根植筋的极限承载力计算公式,提出火灾中植筋混凝土梁耐火极限的计算方法,并与试验值进行对比分析.结果表明,本文公式计算出的植筋构件耐火极限与试验结果能较好地吻合,计算值与试验值的误差都在15%左右,差值一般都在15min以内,可以用该方法进行植筋连接混凝土梁的耐火极限计算.

For quantitative evaluation of fire endurance,this paper presented a prediction method on the fire endurance of post installed rebar beams exposed to elevated temperature.It was based on equivalent section method,which regarded initial sections as ladder sections by strength reduction of concrete and reinforcement under high temperature.The simplified calculation theory about the mechanical properties of members at ambient temperature and the calculation formula of the ultimate strength of single anchored rebar in fire were used.The feasibility of the theoretical calculation was evaluated through a comparison between the results obtained by the prediction method and the experimental measurements.The results showed that the fire endurance calculated by formula agreed well with the test data with the error of 15%,equivalent to about 15 mins.It was feasible to use this method to predict the fire endurance.