Approaches for Increasing the Load Carrying Capacity of Historic Bridges

The historic value of a bridge is generally determined by societal factors. However, the particular character and the rarity of the type of structure, as well as its integration in the environment, may also constitute sufficient reasons to preserve a bridge. Most historic bridges have insufficient load- carrying capacity, either because of deterioration or because the design loads of the past are considerably lighter than today. The options for refurbishment of 4 particular cases of 100-year old bridges are being considered. Two of them are steel truss road bridges across railway installations, a third case concerns a formerly movable railway bridge and the last one a typical 3-span railway bridge supported by cast iron columns. For each case the historic value of the bridge is being assessed and the refurbishment procedure is being explained. From these examples, a set of possible guidelines for designing refurbishment and increase of load-carrying capacity of historic bridges is derived.