Field Performance of Three Stress-Laminated Southern Pine Timber Bridges

Abstract

Three southern pine stress-laminated deck bridges were constructed in late 1991 in Leon County, Fla. The bridges consisted of approximately 7.32 m (24 ft) simple spans and were 10.97 m (36 ft) wide. They were constructed with #2 and better lumber treated with chromated copper arsenate and redried to moisture contents of <12%. A monitoring program for the bridges was undertaken to investigate the use of southern pine lumber treated with waterborne preservatives in stress-laminated bridges. The program began with static load testing in January 1992. The performance monitoring involved gathering data on the moisture content of the decks, force levels in stressing bars, deck deflection, and the behavior of the bridges under static load conditions. In addition, comprehensive visual inspections were conducted to assess the overall condition of the bridges. Based on almost 3 years of field evaluations, the bridges performed well with no major structural or serviceability deficiencies.