Live Load Deflection Performance of Glued Laminated Timber Girder Bridges

Abstract

To demonstrate and possibly to promote the increased use of timber bridges in U.S. transportation systems, various agencies, including the United States Department of Agriculture Forest Products Laboratory and FHWA, have supported research to develop improved glued laminated timber bridges. This project is part of this research and identifies acceptable live load deflection characteristics of timber bridges. The relationship between live load deflection and the condition of the asphalt wearing surface is of particular interest. To accomplish this, eight glued laminated timber girder bridges were selected for testing. The performance of the bridges was investigated under live load tests and through bridge inspections. The structures were load tested with fully loaded tandem-axle dump trucks, and global and differential deflection data were collected. Field tests revealed that a significant amount of the asphalt wearing-surface deterioration is the result of differential deck panel deflection.