Robustness of Ageing Steel Bridges

Abstract Bridges play a fundamental role in global transportation networks, serving as cost‐effective solutions for connecting two points separated by rivers, valleys, or cliffs. Among the various bridge types, steel truss bridges were commonly used in the early 1900s. This type of bridge was a preferred choice due to its ability to cover long spans with a lightweight structure and its rapid construction process. However, increasing commercial activity, climate change, and natural material deterioration have significantly impacted these bridges over the past decades. As a result, steel truss bridges, now up to 100 years old, are subjected to higher loads, extreme climate events, and deterioration processes such as corrosion and fatigue, making them an ageing infrastructure facing modern challenges. Consequently, steel truss bridges stand out as vulnerable elements within transportation networks. Replacement or retrofitting is often not affordable, necessitating the proposal of alternative solutions to address these issues. This study aimed to understand the structural response of steel truss bridges under unexpected events, such as overloads or member loss, and how these failure scenarios are managed by activating alternative load paths (ALPs). Additionally, a monitoring strategy was proposed to track variations in the bridge's structural behaviour and prevent damage propagation. The analysis was conducted through an experimental campaign on a scaled version of a real bridge. Multiple damage scenarios were evaluated to understand ALP activation and the progressive collapse potential.