A collapse-oriented structural monitoring strategy for bridges

In general terms, structural health monitoring aims to assess the existing safety of the structure whilst ascertaining its resilience in the future. The available monitoring technologies and associated techniques are many, with appropriate selection primarily informed by the type of structure and scope of monitoring. Examples include satellite interferometry coupled with specific in-situ measurements, or photogrammetry supported with noncontact vibration measures. This manuscript describes the design and the preliminary results of a bespoke partial collapse-focused structural monitoring strategy for bridges, with particular emphasis on bridges that are near or beyond design life and expected to remain operational. The approach takes its roots from the fact that structural robustness is the antonym of progressive collapse: studying the collapse mechanisms, often triggered by specific conditions, and preventing their chain-activation, implicitly means providing robustness to the whole structure. Considering that the contingent structural design itself anticipates the activation of such triggering configurations by anomalous response to external loads, the strategy proposed herein was to monitor the evolution of such critical configurations and their potential activation. The analysis considered material durability aspects by considering the evolution of the load paths during the bridge’s service life based on dynamic environmental conditions and the effects on structural members and components. In turn, this serves to identify the critical triggering conditions that lead to certain service failures or unsafe to remain operational. The approach was applied to case studies in Italy and Australia, with outcomes informing practical implications for design.