Evaluation of Improved Shear Key Designs for Multi-Beam Box Girder Bridges

摘要

Laboratory tests were conducted to investigate the problem of shear key failurein multi-beam prestressed box girder bridges and to propose a new shear key design. Failure of shear keys will typically not only compromise the load-sharing mechanisms between adjacent girders, but also may lead to the failure of the deck waterproofing system, with attendant corrosion problems. The tests consisted of monitoring relative displacements occurring across intergirder joints, produced by a simulated concentrated wheel load. In order to economically conduct a reasonable number of tests, a 2-D 'slice' of a multi-beam bridge cross section served as the basic test specimen. Finite element analyses of a three dimension bridge model showed that tensile stresses from transverse negative moments in the top flange of the bridge, generated as a result of the continuity provided by the current shear key design, may be responsible for many shear key failures.