Nowadays, deliberate or unwanted fire incidents have created much attention to the behavior of structures against these types of events. Since the properties of structural members are influenced by the increase in the temperature of the members, it is more difficult to predict the general and local behavior of the structures during the fire. In this research, a method has been proposed to calculate the critical temperature in two-dimensional structures at its collapse with desirable accuracy. In this process, the upper-bound theory of plastic analysis is used. The plastic analysis is performed by applying the initial fire scenario to the structure, and its collapse load factor with the corresponding collapse mode is determined. This operation continues until the critical temperature coefficient is acquired, and it occurs when its corresponding collapse load factor equals 1. In addition, the application of the genetic algorithm in the plastic analysis of structures has made this method more applicable to larger frames. Therefore, using this method, without using complex structural analysis and software, the critical temperature of the structures during its collapse, along with their collapse mechanism, both before and during a fire, can be calculated. The investigations on two case studies also confirm the decent accuracy of this approach.

如今，蓄意或不希望发生的火灾事件已引起人们对这种类型的事件对结构行为的关注。由于结构构件的性能受构件温度升高的影响，因此更难预测火灾期间结构的一般和局部行为。在这项研究中，已经提出了一种以理想的精度来计算二维结构在坍塌时的临界温度的方法。在此过程中，使用了塑性分析的上限理论。通过将初始火灾场景应用于结构来进行塑性分析，并确定其塌陷载荷因子和相应的塌陷模式。此操作将一直持续到获得临界温度系数为止，当相应的倒塌荷载因子等于1时，就会发生这种情况。此外，遗传算法在结构塑性分析中的应用使该方法更适用于较大的框架。因此，使用这种方法，无需使用复杂的结构分析和软件，就可以计算结构在坍塌期间的临界温度，以及火灾之前和之中的坍塌机理。对两个案例研究的调查也证实了这种方法的正确性。可以计算建筑物在坍塌之前的临界温度，以及在火灾发生之前和之中的坍塌机理。对两个案例研究的调查也证实了这种方法的正确性。可以计算建筑物在坍塌之前的临界温度，以及在火灾发生之前和之中的坍塌机理。对两个案例研究的调查也证实了这种方法的正确性。