Field Performance Of Timber Bridges

The Byron bridge was constructed in the fall of 1993 in Byron, Maine. The bridge is a single-span, two-lane, stress-laminated truss structure approximately 46 ft long and 32 ft wide. The truss laminations were produced using chromated-copper-arsenate- (CCA- ) treated Southern Pine connected with metal plate connectors. This report includes information on the design, construction, and field performance of the bridge. Field performance was monitored for approximately 5 years, beginning shortly after bridge construction. Performance monitoring involved collecting and evaluating data relative to wood moisture content, force level of stressing bars, behavior under static truck loading, and overall structural condition. The field evaluations showed that the Byron bridge is performing well, with no structural or serviceability deficiencies.

The North Siwell Road bridge was constructed during December 1994 in Hinds County, Mississippi. The bridge is a single span, stress laminated T-beam structure measuring 9.1 m (30 ft) in length and 8.7 m (28.5 ft) in width. Performance of the bridge was monitored for 24 months, beginning at the time of installation. Monitoring involved gathering and evaluating data relative to the moisture content of the wood components, force level of stressing bars, and behavior of the bridge under static load conditions. Comprehensive visual inspections were also conducted to assess the overall condition of the structure. Based on field evaluations, the bridge is performing well.