Experimental Evaluation and Implementation of Post-Tensioning in Concrete Bridge Decks

A research program was conducted to evaluate the design recommendations for transverse post-tensioning of bridge decks developed in the FHWA/IN/JTRP/2002-26 (SPR-2409) report. The test specimen consisted of a 40x18 ft cast-in-place concrete deck on precast pretensioned girders. Thirty-two tests were carried out by applying different distributions of transverse post-tensioning force, in combination with a changing number of diaphragms, and two conditions of end-restraint at the supports. The transverse post-tensioning stress ranged from 400 to 1 200 psi and the number of diaphragms was reduced from five to zero. The main findings support the notion that the presence of diaphragms affects the distribution of transverse strains. However, their influence is not as important as analytical models showed. The influence of end-restraint supports on the distribution of transverse strains appeared to be less significant than estimated by Ramirez and Smith-Pardo (2002). Field-work is recommended to further evaluate the effect of this parameter. The use of elastic theory resulted in good agreement between calculated transverse stresses in the concrete deck obtained from the transverse steel reinforcement and those calculated from strains in the post-tensioning bars. In the range of post-tensioning estimated to maintain uncracked condition under service loads, the use of uniform transverse post-tensioning was deemed appropriate