A new model for determining neutral-plane position in shaft space of a building under fire situation

In this study, a new model is proposed for predicting the location of the neutral plane inside the shaft space of a building under fire situation. The shaft space of the building is divided into two zones, i.e., fire zone and inner space, in the model. The temperature is assumed uniform in each zone. To validate the proposed model, a parametric numerical study is also carried out by using a computational fluid dynamics (CFD) code, i.e., FDS code. The comparisons between the proposed model and the CFD model are processed and the agreements between the two approaches are satisfied. It is found that the location of the neutral plane is above the mid-height of the building and the simulation results are consistent with the proposed model approximately. The ratio of the neutral plane height to ceiling height depends on the ventilation condition of the fire room greatly, which is found varying between 0.50 and 0.62.