Analysis of the Plasco tower in fire using an integrated simulation approach

The Plasco tower, a 16-story building constructedin 1962, was the tallest building in Iran until its collapse in 2017. This iconic high-rise building, known for being one of the largest garment distribution and production centres in Tehran, collapsed due to a fire accident. The fire started on the 10th floor and travelled both vertically and horizontally within the building. The aim of this research work is two-fold, i.e., firstly, to develop plausible theories explaining the collapse mechanism of the partial collapse of the northwest corner of the Plasco tower, a key event during the fire and secondly, to demonstrate the open-source integrated approach used for the investigation, which researchers at Research Centre for Fire Safety Engineering have developed [1], PolyU, Hong Kong. The integrated approach implemented in this work demonstrated the capabilities of FDS and OpenSEES in performing a complete automated sequential analysis of fire, heat transfer and thermo-mechanical analysis at a desirable level of fire load resolution. The study reveals that the partial collapse of the 11th to 13th floors was caused by prolonged fire exposure, thermal restraint, and variations in column movements, resulting in high thermal gradients that led to severe rotation and eventual failure of the beam-column connections. The complex interplay of these factors highlights the vulnerability of fire-affected structures, emphasising the need for designs that can withstand such extreme conditions. This study shows that despite the failure in the corner zone, elevated temperatures in the peripheral northwest columns did not compromise global stability.