Comparative Analysis of the Fire Performance of a Steel Arch Bridge

Bridges are strategic infrastructures and must be designed to withstand operating and exceptional load conditions. However, the current structural standards of bridges do not explicitly consider fire actions. In fact, unlike most structures and infrastructures (buildings and tunnels), there is no specific regulatory obligation that requires the designer to verify a bridge according to fire resistance criteria. However, the fire risk is not negligible, as highlighted by the scientific literature. This aspect can lead to a high vulnerability to the fire of bridges and in the event of a fire, a significant impact on the functionality of the infrastructural network can therefore be expected. The present work fits into this context by analyzing the fire vulnerability of an arched steel overpass with an orthotropic slab deck. Different plausible fire scenarios, such as heavy good trucks, were considered below the bridge and were modelled according to nominal curves and natural fire curves, such as computational fluid dynamics (CFD). A series of thermomechanical analyses were then developed to identify the failure modes and times of collapse, as well as the deformation behaviour that can cause the loss of functionality.