Precast Concrete Deck Panel Performance on Long Span, High Traffic Volume Bridges

摘要

The NHDOT prohibited the use of partial depth precast deck panels on its long span, high traffic volume bridges until it could investigate if the precast slabs and the concrete overpour were acting in a composite manner. The NHDOT also wanted to ensure that there was adequate transfer of traffic loads between the panels without causing reflective cracking. The purpose of this project was to investigate these two issues. The NHDOT reconstructed the deck of the I-393 bridge over the Merrimack River in Concord using precast concrete slabs and a concrete overpour in 2002-2003. Cores were taken from this bridge deck to evaluate the composite behavior of the slabs and overpour and cracking was evaluated. Cores were taken before the introduction of traffic and then after the deck had been exposed to traffic for several months. Cracking was evaluated before and after traffic. The cores taken were subjected to tensile and shear strength testing across the panel/overpour interface and were found to perform satisfactorily. The tests provided conclusive evidence that there was excellent bond between the deck slabs and the overpour and that the strength of the bond was actually improving slightly over time. An inspection of the deck before and after traffic loading revealed that the panels were adequately transferring traffic loading without causing reflective cracking. Based on these results the NHDOT will permit the use of this type of deck construction on long span, high traffic volume bridges.