Evaluation of Truck-Induced Vibrations for a Multi-Beam Highway Bridge

Abstract

Vibrations induced by trucks crossing bridges can add uncertainty to the identification of the structure’s dynamic characteristics, and in some cases, can negatively impact the serviceability performance of the structure. Furthermore, the nature of the vibrations induced by trucks and other vehicles crossing highway bridges is not well-understood in practice and has primarily been evaluated using analytical models and limited experimental studies. This paper presents the results of an experimental study on the characteristics of the vibrations induced by trucks crossing a multi-beam highway bridge. The objective of the bridge monitoring program was to assess the prevalence of overweight truck crossings due to rapid growth of fatigue cracks that had been observed on the steel beams. The bridge monitoring system was triggered to record strain measurements along with camera images of the traffic on the bridge during each truck crossing event. The strain response of the bridge beams were recorded for several thousand truck crossings along with snapshot images of the trucks over a six week period. Several thousand truck crossing events were recorded over the entire monitoring program. The strain measurements and images recorded for over 400 different truck crossing events recorded over a 24 hour period were evaluated in the context of the resulting bridge vibrations and truck characteristics including gross vehicle weight and the spatial lane position. This analysis and results are presented and discussed in this paper.