UTILIZATION OF PARTIAL END RESTRAINT IN BRIDGE STRENGTHENING

The purpose of this investigation is to determine a technique for incr easing the capacity of bridges to accommodate today's increase in load ing. Strengthening existing steel stringers in composite, steel-beam, concrete-deck bridges by providing partial end restraint in shown to b e feasible. The research program included a review of existing literat ure, 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 inv estigation are presented, as well as results from an analytical invest igation of the bridge model when subjected to various degrees of end r estraint. Six different degrees of end restraint were examined. The ac hieved percent reductions ranged from 12% to 26% for midspan strains, 20% to 30% for midspan deflections, and 10% to 32% for beam end rotati ons. The correlation between the analytical and experimental results v erified the basic design assumptions; thus, the analytical models can be used for determining the location and the degree of end restraint r equired to strengthen an existing bridge.