Investigation of Low-Cost Accelerometer Performance for Vibration Analysis of Bridges

Abstract

AbstractThe use of low-cost MEMS accelerometers for dynamic testing and vibration analysis of civil infrastructure has been steadily increasing since these devices first became commercially available. MEMS accelerometers are available with a variety of different input ranges, sensitivities, and with analog or digital outputs. These accelerometers have become ubiquitous in smartphones, and are also used in the majority of the wireless vibration monitoring systems. MEMS accelerometers with analog output capabilities are of particular interest for long-term SHM applications of civil infrastructure systems since they can be easily integrated with the data acquisition systems employed for the many other types of sensors that are often used for these applications. A low-cost MEMS accelerometer with nominal performance characteristics compatible for most bridge monitoring applications was previously evaluated by the authors to assess its performance and capabilities. The primary focus of the prior study was comparing the frequency characteristics of the MEMS accelerometer against a laboratory-grade accelerometer for specific harmonic excitations provided by a laboratory shaker. The present study is a continuation of the prior evaluation. In this study, several of the low-cost, analog output MEMS accelerometers were installed on a cantilever beam that was subject to free vibrations. The dynamic properties of the beam obtained from the MEMS accelerometer measurements are compared and evaluated against those obtained from more conventional instrument-grade accelerometers also attached to the same structure. The objective of the analysis was to evaluate the performance of the MEMS accelerometers in identifying the dynamic characteristics of the system, including natural frequencies, mode shapes, and damping ratios. Vibration measurements from an in-service highway bridge using both the low-cost MEMS accelerometers and a commercially available MEMS accelerometer were also compared and evaluated. This paper describes the testing program and the data analysis approach and compares the dynamic characterization results from the low-cost MEMS accelerometer and the more expensive instrument-grade accelerometers.KeywordsMEMS accelerometersCantilever beamHighway bridgeVibration testing