Membrane-Based Forms for Innovative FRP Bridge Systems through Structural Optimization

Abstract

The use of fiber-reinforced polymer (FRP) composites for new construction is still limited primarily due to high costs and designs based on shapes best suitable to conventional materials. The layered and fiber dominated structure of FRP composites is most efficient when used under in-plane stress demands. Structural forms that most efficiently use tensile stress carrying capacity are membranes or thin shells. An analytical investigation is presented where an innovative optimization algorithm for the integrated shape and laminate optimization of free-form FRP shells was developed and used to generate two new bridge systems that efficiently use FRP composites in membrane-based forms. One concept makes use of a FRP membrane working compositely with a concrete slab to resist flexure while the second uses the FRP membrane in a dual suspension system supporting a deck through diaphragms. The resulting designs and a discussion on their performance under optimal and nonoptimal loading are presented. While practical issues are still to be resolved, the presented approach and concepts can promote and provide insight to efficient structural forms for FRP composites.