An analytical investigation of thermal prestressing method for continuous composite girder bridges

摘要

The negative bending moment near the intermediate supports of continuous composite girder bridges induces tensile stresses in the concrete deck. Although a relatively high ratio of reinforcement is present in these regions, tensile cracks are repeatedly reported. The tensile cracks rapidly deteriorate the concrete deck, giving rise to frequent need for maintenance work. Also owing to the tensile stresses, the concrete deck sections at the negative bending moment regions are ignored in the design process and this kind of design concept is a huge drawback regarding effective use of materials. Prestressing methods are usually utilised in this kind of situation for the concrete structures, but no effective and feasible method has yet been proposed for steel-concrete composite structures. In the current study, a new type of prestressing method entitled the thermal prestressing method (TPSM) is proposed for the innovative construction of continuous composite girder bridges. Basic concepts of the TPSM are introduced and a methodology for computing the TPSM effect is presented with illustrative examples.