Strength Analysis of Precast Bridge Decks with Full-Depth Precast Overhang Panels

Abstract

The use of full-depth precast overhang panels provides an alternative to modern bridge deck construction by eliminating the need to form a full-depth cast-in-place (CIP) overhang. Additional benefits from these precast panels include improving worker safety conditions during construction and accelerating construction. To validate the capacity of a full-depth precast bridge deck system compared with a conventionally constructed concrete bridge deck, the Texas Department of Transportation sponsored an experimental investigation. For both, the failure loads exceeded the maximum factored 2007 AASHTO load and resistance factor design for decks and deck overhangs. Observations suggest that there is an interaction between flexure and shear to estimate the capacity of full-depth concrete bridge deck overhangs or slabs constructed with stay-in-place (SIP) panels and a CIP topping. This paper shows how a modified yield line theory, which accounts for the development length of the mild steel reinforcing to reach yield strength, is used to analyze precast bridge decks with full-depth precast overhang panels. For the full-depth overhangs, the internal work equation is further modified to allow for the panel-to-panel seam that exists within the system. At the interior portions of the bridge deck, a compound shear–flexure mechanism is proposed. This is an additive model of a flexural yield line failure in the lower SIP precast panels and punching shear in the upper CIP portion of the deck. Therefore, a strength method of analysis is used to design the exterior portion (overhang) that incorporates the concurrent effects of flexure and shear in panelized precast deck systems.