Cripple Creek Bridge, Highway 101, Ontario, Canada

Due to deterioration, the entire superstructure of this steel-timber composite bridge was to be rehabilitated. The 3 single spans of 7-18-7 m consist of standard wide flange steel beams at 1.2 m spacing. The existing transverse nail-laminated timber deck was replaced with a longitudinally laminated, transversely prestressed timber deck. The bridge was repaired in two stages to maintain one traffic lane at all times. Transversely prestressed timber decks are stiffer and more durable than nail-laminated timber decks. Prestressing inhibits relative movements between the timber laminates and greatly improves wheel load distribution.

The transverse prestressing system consists of galvanized Ø26 mm DYWIDAG Bars (THREADBAR ^® ) placed at 300 mm spacing. Tensioning was repeated 1 week and 5 weeks after the initial stressing operation, to compensate for the large creep losses in the timber deck system. DYWIDAG Bars (THREADBAR ^® ) easily allow the repeated retensioning both at the time of construction, and in the future if necessary. Connecting of the tendons between the 1st and 2nd stage construction was accomplished by using standard couplers.