Study on Seismic Evaluation and Seismic Retrofit for Exposed Column Bases used in Gymnasiums

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This report presents the results of experimental study on seismic retrofit for exposed column bases by post-installed anchors. Elasto-plastic behavior of exposed column bases and the effect of seismic retrofit are discussed. The test parameter is the number of the post-installed anchors. The test specimen is composed of the steel frame with the braces and the concrete footing beam. Three specimens are tested under horizontal load. The following conclusions can be made :1. The all specimens failed due to fracture in the threaded portion of the previous anchor bolts2. Cracks on the concrete footing beam were observed for the specimens with post-installed anchors. The cracks were caused by the corn failure of the post-installed anchors.3. For the post-installed anchors, the remarkable flexural deformation was observed. This flexural deformation deprived the bond stress between the post-installed anchors and the concrete beam.4. The evaluation for the tensile strength of column bases is available for the all specimens.5. The evaluation for the shear strength of column bases overestimates the test results.