DESIGN AND MONITORING OF A CCA-TREATED STRESSED TIMBER BRIDGE DECK

Use of chromated copper arsenate (CCA) as a preservative in timber bridges can have some economic and environmental advantages when compared to creosote and pentachlorophenol. A related paper by the authors addressed some of the problems with using CCA and outlined some potential solutions. Described in this paper are the overall design and a unique monitoring system developed for the Merrills Bridge, a CCA-treated stressed solid bridge deck, which will be located in the town of Gray, Maine. This bridge, which is scheduled for completion in 1991, features a protected CCA-treated post-tensioned deck and uses Belleville springs at the ends of some of the post-tensioning rods. The performance of this system will be closely monitored. Static and dynamic testing will be performed prior to opening the bridge to traffic. A remote monitoring system will continuously record the response of the bridge to traffic loading and environmental conditions for a period of 5 years.