| The object of this research was to develop practical and economical alternative details to the fully-welded connection, which was severely damaged during the 1994 Northridge earthquake. This goal was accomplished in four phases: design of several basic connection details, a comprehensive finite element analysis of these details, an experimental study on nine full-size specimens, and prediction of strength and stiffness of the connection components based on the known characteristics of the tested specimens. In the first phase, two basic connection details were specified to place the girder plastic hinge away from the face of the column. The second phase investigated the inelastic behavior of these connection alternatives with focus on the connection with the reduced bottom flange component. A 3-D nonlinear finite element model was developed for each detail and a monotonic load was applied. The parameters used in the analytical study included: the depth of the girder and column, hinging column vs. hinging beam behavior, the panel zone distortions, the girder flange thickness, moment to-shear ratio, column axial load, the girder over-strength due to the concrete slab, the amount of the flange force developed by the bottom flange component, and the configuration of this component. In the third phase, nine full-size T-shaped specimens for alternative connections were fabricated and tested to destruction with the quasi-static method. A predetermined cyclic displacement was imposed at the girder tip of these specimens.;These alternative connections eliminated the backing bar, used high quality shop weld, and reduced the high stress and strain demand on the weld. Therefore, the failure of the bottom flange weld did not occur. However, for connections using the bottom girder flange component only, the inelastic mode of failure occurred at the top girder flange weld. Using the reduced flange plate at both the top girder flange and the bottom girder flange was the most effective method to develop large inelastic rotations of the joint with stable hysteretic behavior. |
