This paper briefly reviews the results of nchrp project 12-28(4), methods of strengthening existing highway bridges. The initial task in this investigation was a thorough review of international literature to determine strengthening procedures currently being used andto investigate innovative ideas now being considered. The types of structures that show the most need for cost-effective strengthening were identified. A procedure for determining equivalent uniform annual costs was developed to assist the engineer in determining whetherto strengthen or replace a given bridge. The culmination of the study was the development of a strengthening manual for practicing engineers. The eight sections of that manual, which contain different strengthening procedures, are briefly summarized in this paper. This paper appears in transportation research record no. 1180, bridge design and testing.
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