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火灾下建筑结构的力学分析分为2个层次:1受火作用的结构基本构件的力学分析,如受火梁、柱、楼板分析;2受火构件力学状态的变化对整体结构影响的力学分析,如火灾下建筑结构的连续性倒塌分析。为考察整体结构在火灾下的力学反应,Mostafaei提出了混合火灾试验方法,即对原结构部分构件进行耐火试验,剩余子结构则采用数值分析。通过构件火灾试验与子结构数值模型间的数据交互反馈,模拟整体结构火灾下的力学反应,进而避免直接进行大型结构整体火灾试验。理论上,如果受火构件与无该构件的子结构模型,在任意火灾时刻时的内力、位移均相等,则该结果与整体结构实际火灾下的反应相同。但实际上,由于无法保持任意时刻受火构件与子结构模型的荷载、位移一致,混合火灾试验简化为每间隔时间Δt或温度ΔT对这些参量进行一次同步。给出了构件试验和子结构数值模型间的数据交换路径,并以基本构件的数值试验代替真实火灾试验,通过混合火灾数值试验与子结构模型的交互分析结果,验证了混合火灾试验方法的准确性。
The mechanical analysis of the building structure under fire is divided into two levels: 1 Mechanical analysis of the basic components of the structure subjected to fire, such as by the beam, column, floor analysis; 2 Mechanical analysis of the impact of changes in the mechanical state of fire components on the overall structure , Such as the collapse of the building structure under fire collapse analysis. In order to investigate the mechanical response of the whole structure under fire, Mostafaei proposed a hybrid fire test method, that is, the fire resistance test was carried out on some components of the original structure and the remaining substructure was analyzed by numerical analysis. Through the interactive feedback of data between component fire test and sub-structure numerical model, the mechanical reaction under the whole structure fire is simulated and the direct fire test of large-scale structure is avoided. Theoretically, if the substructure models of the fire-damaged component and the non-component-free model have the same internal forces and displacements at any fire moment, the result is the same as the actual fire response of the whole structure. In practice, however, the hybrid fire test is simplified to synchronize these parameters once every interval Δt or temperature ΔT because the loads and displacements of the fire and sub-structure models can not be kept consistent at any time. The data exchange path between component test and substructure numerical model is given and the real fire test is replaced by the numerical test of the basic component. The accuracy of the hybrid fire test method is verified by the interaction analysis between the numerical experiment and substructure model of fire .