Field performance of stress-laminated timber bridges on low-volume roads

Abstract

Stress-laminated timber bridges were first introduced in the United States in the late 1980s. Since that time, the concept of stress-laminating has received a great deal of attention and hundreds of bridges have been built. Most of these bridges are located on rural low-volume roads. To evaluate the performance of stress-laminated bridges, the United States Department of Agriculture (USDA) Forest Service, Forest Products Laboratory, implemented a nationwide bridge monitoring program in 1988 that was subsequently expanded in 1992 to include a cooperative program with the Federal Highway Administration. This paper presents a summary of monitoring results and observations obtained through that program for stress-laminated bridges that have been continuously monitored for 2 years or more. Included are discussions related to bridge construction, moisture content, stressing-bar force, vertical creep, load test behavior, and condition evaluation. Based on the monitoring program results, performance of stress-laminated timber bridges is generally satisfactory, although observed performance can be improved in several areas.

Citation

Ritter, M. A.; Wacker, J. P.; Duwadi, S. R. 1995. Field performance of stress-laminated timber bridges on low-volume roads. Proceedings of the 6th International Conference on Low-Volume Roads, 1995 June 25-29, Minneapolis, MN. Washington, DC : National Academy Press, 1995.:p. 347-356.