Optimizing the Design of Bridge Deck Overhangs.

摘要

Bridge deck overhangs are designed to resist dead and live loads applied to the overhang as well as collision forces applied to the bridge railing. Recent changes in AASHTO design requirements, however, has led to overhangs designed with significantly more reinforcement relative to past practice. The objective of this research is to investigate the potential of using reduced amounts of reinforcement in the overhang while maintaining safety. Two scaled overhang specimens were tested with one specimen containing deck reinforcement according to the current AASHTO design specifications, and the other specimen containing half this amount of reinforcement. The study evaluated the failure mechanism of the overhang, strain distribution in the slab, and displacements along the length of the overhang specimens. Both specimens experienced anchorage failure of the top transverse bars in the slab which led to the formation of a flexural hinge over the entire deck/barrier interface. Behavior of the barrier/deck system was further evaluated using yield line analysis, and this evaluation supports the overall measured behavior which is different from that assumed by the AASHTO specifications. This research indicates that improvements of design assumptions may be possible which can lead to a reduction in reinforcement required for bridge deck overhangs.