Strengthening of bridge decks by adding new concrete layers

Deterioration or need to increase the load bearing capacity of bridge decks requiresthe strengthening of the decks by the addition of new elements. Placing reinforcedconcrete layers to strengthen or repair and strengthen concrete bridge decks on the compressionor the tension side of the element is a normal construction practice. However, there aremany unresolved issues regarding the capacity and the interface behaviour between the existingdeck and the new layer of the strengthened elements especially under seismic actions. Thenew deck created is a reinforced concrete composite member. In the present study an analyticalmodel has been developed for the estimation of the ultimate strength of such a compositedeck. The shear stress at the interface of the function results from experimental data and dependson the connecting means. The influence of cyclic loading on the behaviour of the interfacebetween the new concrete layer and the existing deck is considered. The model iscomplemented by a computer program in order to facilitate the relative calculations. Finally,an analytical procedure for the structural design and detailing of strengthened or repairedand strengthened bridge decks by the addition of new concrete is proposed. Moreover the inducedshear stresses and forces at the interface can be assessed to design the necessary connectionmeans, in order that there will be no failure of the contact interface, before theretrofitted deck reaches its flexural capacity.