Robustness-based assessment and monitoring of steel truss railway bridges to prevent progressive collapse

Risks of bridge collapse were and continue to be real as evidenced by classical (e.g. Québec Bridge, Canada 1919; Seongsu Bridge, South Korea 1994) and recent (e.g. Skagit River Bridge, USA 2013; Francis Scott Key Bridge, USA 2024) episodes of catastrophic collapses. The causes of each collapse are diverse (e.g. natural disasters, changing conditions, design errors, intentional attacks). Still, the conclusions are always the same: deaths, injuries and large amounts of direct and indirect economic losses. In order to avoid these catastrophes, structural robustness and monitoring strategies can be used to analyse the bridge's vulnerability and anticipate any local-initial failure that can spread to the whole structure in the form of a progressive collapse. The objective of this work was to use an integrative threat-dependent and threat-independent approach to analyse the structural robustness of a never-before-studied U-shaped open cross-section steel truss railway bridge structure. Eight failure scenarios were considered and analysed through computational modelling. The extracted results make it possible: (i) to connect structural robustness analysis outputs with the definition of a new structural health monitoring strategy of the bridge; and (ii) to implement the conclusions in the real bridge with more than 100 sensors and a non-assisted alarm system for preventing progressive collapse.