FATIGUE OF CURVED STEEL BRIDGE ELEMENTS--DESIGN RECOMMENDATIONS FOR FATIGUE OF CURVED PLATE GIRDER AND BOX GIRDER BRIDGES

Research on the fatigue behavior of horizontally curved, steel bridge elements was conducted at Fritz Engineering Laboratory, Lehigh University, under the sponsorship of the Federal Highway Administration (FHWA) of the U.S. Department of Transportation. The multi-phase investigation spanning nearly five years was performed in five Tasks: 1) analysis and design of five large scale horizontally curved steel twin plate girder assemblies and three large scale horizontally curved steel box girders, primarily for fatigue testing, 2) special analytical studies of the influences on fatigue of stress range gradient, heat curving, "oil canning" of webs and the spacing of internal diaphragms in curved box girders, 3) fatigue tests, to 2,000,000 cycles, of each of the above eight curved test girders, 4) ultimate strength tests of three of the curved plate girder assemblies and two of the curved box girders following the fatigue tests (composite reinforced concrete slabs were added to two of the three curved plate girder assemblies and to both curved box girders) and 5) development of design recommendations suitable for inclusion in the AASHTO bridge design Specifications. This is the eighth and final report of the project and presents the results of Task 5 above. The entire project is described and the findings summarized which were presented in the previous project reports. The report concludes with suggested additions and modifications to the Tentative Design Specifications for Horizontally Curved Highway Bridges, prepared for the FHWA-DOT by CURT under Contract Number FH-11-7389, March 1975. (FHWA)