高温下装配式钢牛腿连接节点破坏机理及影响参数分析

Analysis of failure mechanism and influencing parameters of prefabricated steel bracket connection under high temperature

为了研究高温下装配式钢牛腿连接节点的破坏过程、破坏形态和破坏机理,以及不同荷载、偏心距、肋板厚度、栓钉直径和角钢厚度对节点温度分布、耐火极限及位移曲线的影响规律,通过ABAQUS软件建立了装配式钢牛腿连接节点的有限元模型,并用试验结果验证了模型的准确性。结果表明:侧板屈服的平均临界温度为516.54℃。肋板屈服的平均临界温度为583.38~691.42℃。肋板破坏的平均临界温度为610.85~728.96℃。高温下节点最终的破坏形态有三种:肋板局部屈曲;肋板局部鼓曲;栓钉屈服。节点的耐火极限随着肋板厚度的增加、荷载的减小、等肢角钢厚度的增加而增加。偏心距的改变会改变肋板高温下的破坏形态。栓钉直径增加会导致栓钉温度升高,对提高节点耐火极限有不利影响。

In order to study the failure process,failure mode,and failure mechanism of the prefabricated steel bracket connection at high temperature,and the influence of different loads,eccentricity,rib thickness,stud diameter,and angle steel thickness on the temperature distribution,fire resistance,and displacement curve of the connection,the finite element model of prefabricated steel bracket connection is established through ABAQUS,and the accuracy of the model is verified by the test results.The results show that the average critical temperature of the side plate yield is 516.54℃.The average critical temperature range of rib yield is 583.38~691.42℃.The average critical temperature range of rib failure is 610.85~728.96℃.There are three final failure modes of connections under high temperature:1)local buckling of the rib;2)local bulge of the rib;3)yield of the stud.The fire resistance of connections increases with the increase of rib thickness,the decrease of the load,and the increase of equal-leg angle steel thickness.The change of the eccentricity will change the failure mode of the ribs at high temperature.The increase in diameter of the stud will cause the temperature of the stud to increase,which harms improving the fire resistance of the connection.