Utilization of partial end restraint in bridge strengthening

Abstract

The purpose of this investigation is to determine a technique for increasing the capacity of bridges to accommodate today's increase in loading. Strengthening existing steel stringers in composite, steel-beam, concrete-deck bridges by providing partial end restraint is shown to be feasible. The research program included a review of existing literature, testing of a full-scale bridge beam and a 1/3-scale bridge model, and finite-element analyses of the restraint brackets, the test beam, and the model bridge. Analytical and experimental results of this investigation are presented, as well as results from an analytical investigation of the bridge model when subjected to various degrees of end restraint. Six different degrees of end restraint were examined. The achieved percent reductions ranged from 12% to 26% for midspan strains, 20% to 30% for midspan deflections, and 10% to 32% for beam end rotations. The correlation between the analytical and experimental results verified the basic design assumptions; thus, the analytical models can be used for determining the location and the degree of end restraint required to strengthen an existing bridge. Key words: bridges, girder, composite structures, tests, models, strengthening, rehabilitation, restraint.