Study of Shape Coefficient in BFD Model

BFD model for predicating smoke temperature of large space building can accurately predict the temperature field distribution of the whole process of fire, but the shape coefficient of important parameters in the model is not comprehensive. In this paper, several important factors affecting BFD model had been discussed and the value of shape coefficient (w1/w2) in different fire scenarios had been given. Temperature field distribution under various condition had been gained through simulating more than 20 kinds of fire scenarios by FDS, then the appropriate value of w1/w2 had been determined by fitting of origin. Finding that the fire growth factor has a decisive effect on w1/w2, and same w1/w2 can be used in BFD model in different position below the ceiling under the same fire scenario. Meanwhile that building height and area have little impact on w1/w2 under H>6m or S>1500m2 had been validated again. Therefore, BFD model application has been greatly simplified and the temperature of BFD model using above w1/w2 are in accordance with the results of FDS simulating for large space building. Based on the results obtained, the possibility of applying BFD model into engineering field becomes very high.