Ultimate Load Test of Truss Bridge Floor System

An old pin-connected high-truss single-lane bridge, located in an area which will be flooded due to the construction of the Saylorville Dam, was tested to failure. Only the portion of the testing program related to the ultimate load testing of the timber deck is examined herein. Each deck panel was tested to failure using simulated axle load which was applied by hydraulic jacks. One deck panel was tested with the loads centered and the other was tested with the loads eccentrically placed with respect to the center line of the bridge deck. The behavior of the deck, at loads up to failure of one of the stringers, compared quite well with that predicted by the AASHO Specifications. The deck was rated by three different agencies. Although there was some variation in the ratings, they compare favorably and are approx 32% of the test capacity.