Prestressing of simply supported composite bridges: a cost-benefit analysis

Composite bridges can be prestressed both with internal bonded prestressing in the slabs and with external unbonded prestressing fastened on the steel beams. This technique is generally employed in continuous bridge beams in order to contrast upper slab cracking due to negative bending moments on internal supports. Con-versely, this work presents a parametric analysis aimed at understanding if (and to which extent) prestressing can be beneficial in simply supported composite bridges for reducing the profile section and, hence, the de-mand for ordinary steelwork. Therefore, the effect of both different levels of prestressing action and alterna-tive sequences of construction is taken into account. Moreover, closed-form solutions for Class 3 sections and iterative solutions for Class 4 ones are considered. Finally, a cost-benefit analysis is presented.