CODE PREDICTIONS VERSUS SMALL SCALE BRIDGE DECK MODEL TEST MEASUREMENTS

This paper presents the test results of eight 1/6.6 bridge deck models of an 8.5 in. thick and 50 ft long prototype concrete bridge deck supported on four simply supported steel girders spaced at 7 ft or 10 ft and subjected to a static concentrated wheel-load. The effects of the lateral restraint, girder spacing and amount of reinforcement on the behavior of the deck is determined and discussed. In addition to the enhancement of the ultimate load carrying capacity of the deck, membrane compressive forces present in the deck may shift the primary failure mode from a flexural type to that of punching shear. The effect of this arching action mechanism on the bridge deck response explains the differences between the observed ultimate strength values and the shear strength predictions by the ACI 318 and the European CEB Code. The shear capacity code predictions are conservative (down to about 28% of the measured ultimate strength values). The level of restraint (deck continuity) in a non-composite bridge deck affects the arching action mechanism considerably higher than the amount of reinforcement specified by the AASHTO and Ontario design approach and the girder spacing used in existing highway concrete bridge decks (7 to 10 ft).