Evaluation of Plasco Building fire-induced progressive collapse

This paper presents a comprehensive structural assessment of the fire-induced progressive collapse of Plasco Building, in January 2017. The assessment employs a three-phase approach: a) field investigation to collect data about the building and the event, b) structural evaluation against service loads, c) progressive collapse analysis. A collapse scenario is proposed, which is simulated using finite element modelling and numerical analysis. The results showed the adequacy of the building for service loads, while its significant vulnerability against progressive collapse. The vulnerability was mainly due to the lack of adequate continuity, ductility, and redundancy to resist the spread of damage. The weakest link in the structural system was the beam to column connections, which reached their critical temperatures first and failed to resist the local failure loads. Furthermore, exposure of unshielded structural components to the fire had led to a more severe condition, which eventually by the occurrence of failures over consecutive stories, buckling of the columns, and significant change in the geometric shape of the structure, the total collapse of the building occurred. The results of this investigation are considered as valuable tools for recognizing the deficiencies of the structural provisions in Iran against such events.