In Situ Materials and Structural Assessment of Stress-Laminated Deck Bridge Treated with Chromate Copper Arsenate

A bridge consisting of three 6.7-m spans with a stress-laminated deck was constructed in 1991 in the Spirit Creek State Forest near Augusta, Georgia. The bridge was constructed by the Georgia Forestry Commission, with guidance from the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory (FPL). Water-borne chromated copper arsenate lumber was used for the deck, instead of the oil-borne preservatives recommended by AASHTO. The bridge was initially monitored by FPL and remained in service from 1994 to 2001 with no maintenance, at which time the bridge was inspected and load tested and the posttensioning bars were restressed. In 2005 the bridge was again inspected and load tested, and the bars were retensioned. The results of the inspection and load tests are presented. The overall condition of the bridge is reported, along with details on the moisture condition, overall deck deflection, and timber strains under load. Details on the loss of posttensioning forces in the bars, and an investigation of the causes of this loss, are presented.