InTrans / Aug 14, 2018

Field Performance of Timber Bridges: 4. Graves Crossing Stress-Laminated Deck Bridge

The Graves Crossing bridge was constructed October 1991 in
Antrim County, Michigan, as part of the demonstration timber bridge program sponsored by the USDA Forest Service. The bridge is a two-span continuous, stresslaminated deck superstructure and it is 36-ft long and 26-ft wide. The bridge is one of the first stress-laminated deck bridges to be built of sawn lumber treated with chromated copper arsenate (CCA) preservative. The performance of the bridge was continuously monitored for 2 years, beginning at the time of installation. This performance monitoring involved gathering and evaluating data relative to the stiffness of the lumber laminations, the moisture content of the wood deck, the force level in the stressing bars, and the behavior of the bridge under static truck loading. In addition, comprehensive visual inspections were conducted to assess the overall condition of the structure. Based on 2 years of field observations, the bridge is performing well with no structural or serviceability deficiencies.