Enhanced structural health monitoring of ageing Pratt truss bridges: a combined approach of static and dynamic measurements

Abstract

The application of SHM has been broadened to the issues of preserving existing bridges, which are subjected to many years of usage and exposure to environmental factors. This paper aims to demonstrate the effectiveness of SHM in the maintenance and management of ageing structures, specifically a Pratt-truss steel bridge in Malaysia. The research combines static and dynamic methodologies to describe the ancient bridge’s serviceability. Operational modal analysis and FE analysis were first used to evaluate the structure's inherent frequencies and mode shapes, followed by a successful sensitivity-based model updating method. Next, static measurements were automated using displacement and strain data to evaluate the bridge’s condition. According to the study, the first four crucial bending and torsion modes for the ageing steel truss bridge occur between 4 and 29 Hz. Since the two approaches yield different MAC values and frequencies, employing a sensitivity analysis and model update procedure has become necessary. The frequency reference generated with EN1991-2:2003 bridge frequency constraints was then used to determine the bridge’s integrity, concluding that the bridge is safe and functional. Finally, the static analysis findings showed that the bridge is in a safe service condition regarding its deflection limit and strain limit.