Evaluation of Economical Dynamic Exciters for Vibration Testing of Bridges

Abstract

Quantitative data describing condition and performance is essential for evaluating the structural health of bridges. Dynamic testing is a common approach for globally characterizing bridges in a quantitative sense. Dynamic testing is most commonly accomplished for full-scale bridge structures through either forced vibration testing or ambient vibration testing methods. Forced vibration testing offers many advantages, but is generally not a practical or economical approach for many bridges due to the high cost of providing controlled excitation, limits to the excitation that can be supplied, and interference with the normal operation of the bridge. The writers have been investigating the feasibility of using low-cost, small-scale dynamic exciters for forced vibration testing of short to medium span bridges. The exciters being evaluated have a unit cost that is comparable to a typical accelerometer, and could be deployed in numbers using a spatially distributed setup for forced vibration testing. This paper presents and describes the results of a laboratory evaluation program conducted for these devices. Their capabilities and operating characteristics are compared with a more conventional linear mass shaker. The preliminary results of a vibration test using these devices on an in-service highway bridge are also discussed.