Abstract Manager

Existing integrity evaluation approaches for bridges mostly depend on visual inspections and assumption-based theoretical models. In more recent years, structural health monitoring systems (SHM) have been permanently installed on a few landmark bridges in North America. Due to several shortcomings including frequent maintenance, wired systems, difficulties in installation, and low levels or non-existent data analysis, these systems have been unsuccessful in providing a practical insight into a structure’s integrity. As a result, they have not been adopted on a large scale. Therefore, there is a need to develop a novel SHM system that is easy to install, wireless and based on in-depth data analysis to provide actionable insights about bridge integrity to asset owners.

This paper presents a state-of-the-art approach developed by Sensequake to provide an advanced structural health monitoring solution using ambient vibration testing to evaluate the integrity of bridges. This novel method is data-driven and evaluates the condition of all major bridge components including foundations, piers, abutments, bearings, deck, and potential scour from sensors deployed only at the deck. In this paper, the performance of this method is shown on three continuous three-span bridges in Northwestern Ontario including the Mackenzie Twin Bridges and the Pic River Bridge owned and operated by the MTO. The ambient vibration data are collected for only a few hours using Sensequake’s highly sensitive and synchronized Larzé sensors across six channels thanks to a combination of triaxial velocimeters and triaxial accelerometers. Through in-depth processing of the measured data, multiple dynamic properties (natural frequencies, high-quality animated 3D mode shapes, and damping ratios) including higher modes are precisely identified, serving as the stiffness baseline of a bridge.

Sensequake’s damage detection approach is based on comparing a bridge’s stiffness baselines (dynamic properties) with similar bridges within Sensequake’s database of healthy and unhealthy bridges and by periodically comparing them with the bridge itself over the bridge’s lifetime. This unique approach precisely examines any change in the mode shapes and resonance frequencies to detect, locate, and quantify structural damage that may compromise a bridge's integrity. By comparing the extracted dynamic properties with the expected ones from a healthy bridge, the observed anomalies in the mode shapes can be correlated to physical damage and identifying the damaged structural component. Sensequake’s technology is capable of significantly enhancing the performance of structural health monitoring systems and contributing to a rapid and more reliable assessment of bridges.