On the use of steel-free concrete bridge decks in continuous span bridges

Abstract

This note discusses the use of the steel-free concrete bridge deck technology in continuous span bridge structures. Conventional slab-on-girder design often utilizes the longitudinal steel reinforcement in the deck to resist the negative bending moments created at the internal piers of continuous bridges. The steel-free bridge deck is devoid of all internal steel reinforcement and hence requires an alternate design approach which is presented in this note. A key aspect of this approach is the recommended use of fibre-reinforced polymer reinforcement to control cracking of the deck over the intermediate supports. Limiting these crack widths is essential to the durability performance of the concrete, particularly in freeze-thaw environments. The results of an experimental program are also reviewed. The tensile stresses from the global longitudinal negative moment are shown to have little effect on the punching behaviour of the slab. It is noted that the concepts presented in this note were utilized in the construction of a three-span highway bridge which incorporated the steel-free bridge deck technology.Key words: bridges, design, continuous span, concrete decks, punching-shear, fibre-reinforced polymers.