Aluminum Structures Covered with PVC Tents Collapsing under a Severe Rain Event

Marquee structures are widely used for covering large spaces for temporary or permanent purposes, cultural and sporting events, exhibition spaces for trade fairs or commercial activities, or as temporary environments for civil protection in the event of emergencies and calamities - for example, as collection points after earthquakes, floods, etc. This work focused on the effect of ponding on the membrane tent of marquee structures and the risk of failure due to water accumulation. This article presents an example of a structure that recently collapsed in Italy during heavy rain. The collapsed aluminum structure had plane dimensions of 14,900×25,500 mm and height 6,000 mm and was covered with a polyvinyl chloride (PVC) membrane. During the month of August 2022, after heavy rain, depressions formed on the roof that led to the accumulation of very high quantities of water, leading to progressive collapse of the building. The lesson learned from this case is that ponding effects can lead to accumulation of water and produce second-order effects on structures. which effects can be predicted with second-order analyses under large displacements and considering fluid-to-structure interactions, which, if not taken into account, can lead to the collapse of the structure. Finally, it should be stressed that, due to climate change, the risk of roof collapse due to ponding is likely to increase in the future. In the paper, a simple calculus model based on the determination of water accumulated in the deformed shape of a roof transformed in equivalent distributed load is presented.