Alternative Layout for the Prestressing of Slab Bridges

On the basis of a statically admissible moment redistribution in rectangular and skew slab bridges with free edges parallel to the bridge axis, an alternative positioning of the prestressing tendons concentrated at the outer edge regions is studied, with regard to the fulfillment of the respective strength conditions. The moment redistribution is adapted to the available bending resistances across the slab and is accomplished not only through the inherent statically indeterminate plate response, but also through the use of an additional fictitious loading achieving a self-equilibrating state-of-stress condition. It is shown that with the selection of appropriate values for some nondimensionalized design parameters that are introduced herein, a substantial economy in the use of prestressing steel can be attained as compared to the uniform arrangement of prestressing tendons across the whole slab, resulting in a clear savings in total material cost. The partial prestressing that has been implicitly adopted shows an acceptable performance at the service level.