火灾影响下RC梁的时变可靠性分析

Time-dependent Reliability Analysis of RC Beam Under Fire

通过分析火灾发生时RC梁截面内温度场的分布,得出了火灾后RC梁的抗力折减系数,建立了火灾后RC梁的抗力计算模型,同时引入了火灾前抗力和荷载效应随时间而变化的动态可靠性,对长期使用后又遭受火灾作用的RC梁可靠性进行了分析,分析过程中考虑了火灾前后两个过程可靠性的相关性。算例分析表明,使用时间和高温作用及两个过程的相关性对梁的可靠性都有一定的影响,在有条件的情况下应给予考虑。

Through analyzing on temperature field of RC beam under fire, the reduced coefficient of resistance of RC beam after fire is got, and corresponding calculated model is formed, meanwhile, time-dependent reliability is induced, in which the changes of resistance and load effect before fire with time are considered. The reliability of the RC beam that is under long-term service and subjected to fire is analyzed. During the process of analysis, correlation of reliability of the two procedures between before fire and after fire is also considered. Calculated example results indicate that service time and high temperature and the correlation all have some influences on reliability, all which should be considered under some conditions.