Fused Bridge Structures for Higher Impact Resistance

Accidental overloading such as vehicle impact causes significantly larger loading to structures than normal service load, which requires a larger safety margin in design and consequent higher construction costs. Safety margin and construction costs are two conflicting goals for structural design. By providing a fuse in a structure that is triggered at a certain level of overloading, further increase of loading can be prohibited and failure of the structure is changed to a safer mode. Control of overloading reduces the partial safety factor for loading. Enforcement of a safer failure mode further reduces the demand for safety reserve. Therefore, such a fused structure requires a significantly smaller safety margin, leading to more economical construction without compromising safety. The use of a fuse will also facilitate safer use of advanced construction materials such as fiber-reinforced polymer (FRP) composites. In this case, a fuse can transfer the sudden and dangerous failure mode associated with brittle FRP debonding or rupture to a safe and ductile failure mode at the fuse location. This paper introduces a new type of fused structure as well as an associated design philosophy and approach that is suitable for structures with high impact resistance.