Experimental Evaluation of Low-Cost Accelerometers for Dynamic Characterization of Bridges

Abstract

The design of structural health monitoring systems for bridges often requires that the measurement objectives be carefully balanced with associated cost and logistical considerations. Using accelerometers to measure and track the dynamic characteristics of a bridge is a frequent objective with many potential benefits; however, instrument-grade accelerometers are often the most expensive sensors employed in a structural health monitoring system for a bridge. This often leads to compromises in terms of the number of accelerometers deployed, or a reduced emphasis for vibration measurements in the hierarchy of measurement objectives for the project. Various low-cost MEMS accelerometers are commercially available and can potentially complement or serve as alternatives to instrument-grade accelerometers for structural health monitoring of bridges. Such MEMS accelerometers are used for wireless accelerometer and sensing systems, and the accelerometer chip is integrated on a circuit board with additional electronics for power, data acquisition and communications. In the more common design of structural health monitoring system employing wired sensors of various types, a low-cost MEMS accelerometer that provides analog outputs, and that also has very minimal packaging and electronics integration requirements is most desirable. A study was initiated to experimentally evaluate the performance and capabilities of a low-cost accelerometer that met these requirements for bridge vibration measurements. The low-cost accelerometer’s performance was compared to a more conventional instrument-grade accelerometer. Measurements were recorded by both sensors from a simple physical model and from a full-scale highway bridge structure and evaluated for different vibration measurement scenarios. The capabilities, limitations and optimal application scenarios for the low-cost accelerometers in the context of bridge vibration measurements are presented and discussed.