Load Tests of a through Truss Bridge before and after the Installation of an Arch-Superposition Scheme

摘要

Because so many pinned and riveted truss bridges currently are classified as structurally deficient, a need to develop an economical, practical alternative to bridge replacement exists. Rehabilitation by an arch-superposition scheme can effectively reduce truss member stresses and increase the bridge load capacity. This was verified by load tests conducted both before and after the installation of the arch-superposition scheme to Northumberland Country bridge number 50. The results showed that truss member stresses and deflections can be reduced at least 50% by the scheme which is approximately one-seventh the cost of bridge replacement. Bridge number 50 has been upgraded from a six to a 20 ton inventory rating. The theory, economics, and construction feasibility of the arch-superposition scheme have been verified.