Can fire cause the collapse of Plasco Building: A numerical investigation

Since the tragic event of the World Trade Centre (WTC), efforts to understand realistic fire behaviour in tall buildings are accelerated. It is critical to understand the fire dynamics involved in a compartment fire before performing a forensic investigation of a fire accident. In this paper, various fire scenarios are considered to simulate the behaviour of fire in a high-rise building and demonstrated the case of the Plasco Building using computationally fluid dynamics (CFD). Two fuel distribution patterns are assumed with different packing densities as clothes placed throughout the compartment in a scattered form (similar as in racks) and densely packed as stacked (stored in cartons). It is observed that the distribution of the fuel highly influences the duration of the fire, peak temperatures, and the severity of the fire. The fuel distribution also affects the spread of the fire in both horizontal and vertical directions, which helps in understanding probable fire scenario responsible for the collapse of a building. A case of subsequent heat transfer analysis in an OpenSEES FE model is conducted to represent the extent of temperature reaching the structural elements where temperature data from FDS are used as thermal boundary conditions. Large variations in the temperature of the structural members have been observed between two fuel distributions, which can be a governing factor while analysing structural behaviour in fire conditions. This paper provides insight into performing a forensic investigation of fire collapsed high-rise buildings based on visual evidence.