Strength of reinforced concrete bridge decks under compressive membrane action

Compressive membrane action often exists in the deck of reinforced concrete beam-and-slab bridges, enhancing the deck strength above that determined using a normal flexural and punching shear strength theory. Approximate methods to account for compressive membrane action have been developed by previous researchers. These methods require knowledge of the restraint stiffness that exists for the slab, and this is not known with much certainty. Hence, compressive membrane action is usually not taken into account when determining the strength of reinforced concrete slabs. This paper presents a design method for assessing the restraint stiffness that exists for the slab of typical beam-and-slab bridge decks and the strength enhancement due to compressive membrane action. This gives a more accurate prediction of the strength of the slab. The method has been developed through the laboratory testing of concrete specimens and the use of nonlinear finite element modeling.