A Better Way to Assess Bridge Health

Can you assess the overall condition of large bridges just by driving over them? Indirect health monitoring (IHM) of bridges involves driving one or more sensor-equipped vehicles over a bridge to gather data that can be used to assess its condition. These vehicles subject the bridge to forces which create vibrations in the bridge that can then be recorded by the vehicles and analyzed to examine the bridge's structural properties. 

In a paper in Advances in Bridge Engineering, Exponent's Omar Abuodeh and Laura Redmond from the Glenn Department of Civil Engineering at Clemson University investigated the advantages and challenges of employing multiple vehicles to conduct system identification — or the capacity to identify pertinent features in a physics-based system by utilizing sensor measurements — for IHM of bridges. The authors' goal is to identify configurations, including the number of vehicles, their travel speeds, and relative positions, that enhance the ability to discern a bridge's modal properties, which can be used as indicators to describe its structural capacity, from vibrations measured by passing vehicles.

Extracting bridge frequencies from this kind of vibration data is challenging due to noise from vehicle dynamics, bridge stiffness and mass, road roughness, and environmental factors. Prior studies typically used simplified models (e.g., single vehicle, limited bridge types, unrealistic parameters, or very low speeds). Abuodeh and Redmond used higher fidelity modeling to explore how to develop a protocol for employing multiple vehicles when conducting IHM in bridge structures.

Through simulated tests, their research demonstrates that using multiple vehicles can improve bridge feature detection in IHM by increasing the amplitude of the bridge's vibration within the vehicle's sensor compared to other sources of vibration. When vehicles are strategically spaced and operated under general speed ranges, the resulting vibration data offer clearer insight into the bridge's modal properties than data from single-vehicle tests alone. The findings suggest that coordinated multi-vehicle monitoring could make IHM a more practical and accurate tool for large-scale infrastructure assessment. This technique has the potential to reduce costs, streamline data collection, and support proactive maintenance of critical transportation structures.

From the publication: "Findings reveal that heavier and faster leading vehicles facilitate bridge frequency extraction."