InTrans / Aug 14, 2018

Field performance of timber bridges: 10. Sanborn Brook stress-laminated deck bridge

The Sanborn Brook bridge was constructed in August 1991,
10 miles northeast of Concord, New Hampshire, as part of
the demonstration timber bridge program of the USDA Forest
Service. The bridge is a simple-span, double-lane, stress laminated deck superstructure constructed from Southern
Pine lumber and is approximately 25 ft long and 28 ft wide
with a skew of 14 degrees. The performance of the bridge was
monitored continuously for approximately 2 years, beginning
shortly after installation. Performance monitoring involved
collecting and evaluating data pertaining to the moisture
content of the wood deck, the force level of the stressing bars,
the deck vertical creep, and the behavior of the bridge under
static-load conditions. In addition, comprehensive visual
inspections were conducted to assess the overall condition of
the structure. Based on field evaluations, the bridge is performing well, with no structural or serviceability deficiencies.