Realtime DFOS Based SHM of a Highway Bridge

Abstract

The bridges built during the years of rapid expansion of the European transport infrastructure in the 1960s to 1980s are currently reaching the end of their service life. Decades of increasing traffic loads as well as corrosion reduce the structural capacity. In many cases, replacement of the bridges has already been planned, but planning and construction take time. This is where Structural Health Monitoring (SHM) comes into play, enabling structures to remain in operation even when in critical condition.

The focus of the system introduced here is the reliable detection of tension wire breaks, crack detection and the early assessment of the consequences for operational safety. The measurement technology includes high-resolution distributed fiber optic strain sensors (DFOS) along all bridge girders as well as acoustic emission sensors (AE) and acceleration sensors (ACC). While the latter two systems can be regarded as standard or established, DFOS is relatively new in the field of bridge monitoring. Its unmatched suitability for crack detection has been proven in many laboratory applications and scientific studies in recent years. Individual structural installations have been implemented, but usually as discontinuous measurements taken on specific dates.

In this project, DFOS is used as a permanent system that automatically analyzes crack activity and feeds information into an alarm system in real time, as well as visually processing it in a specially developed dashboard and linking data to a digital twin.