Investigation of Ultimate Strength of Deck Slabs in Steel-Concrete Bridges

Abstract

Many bridges are composite structures with reinforced concrete decks supported by longitudinal steel beams. The presence of the longitudinal steel beams and the unloaded area of concrete slab cause the loaded deck slabs to be restrained against lateral expansion. This creates a compressive membrane (or arching) action. This study uses experimental tests to investigate the effects of structural variables on the load capacity of the deck slabs of the composite bridges. A practical design approach is presented to assess the restraint stiffness that exists in the composite bridge deck and thereby the strength enhancement due to arching action. A series of one-third scale steel-concrete composite bridge models were built with several varying structural parameters, including concrete compressive strength, reinforcement percentage, and the size of steel supporting beams. After comparing the results of different models, the influence of these structural parameters on the amount of compressive membrane action in the deck slab was evaluated. Experimental results showed that compressive membrane action is influenced by concrete compressive strength and lateral restraint stiffness. The proposed method provided accurate, consistent but slightly conservative predictions for the strength of a wide range of deck slabs.