Cyclic shear behavior and shear strength of steel tubed-reinforced- concrete short columns

摘要

The steel jacketing approach is effective and economic for retrofitting reinforced concrete short column. Steel jacketed concrete columns are referred as steel tubed-reinforced-concrete columns when applying in new building structures. To investigate the cyclic shear behavior and shear strength of tubed-reinforced-concrete short columns with a large diameter-to-thickness/width-to-thickness ratio (D/t), four specimens were designed and tested under a constant axial compression combined with quasi-static cyclic lateral loading. Three main system parameters were considered in the test: (1) type of column cross section (circular and square), (2) D/t (106-150), and (3) axial load ratio (0.4 and 0.6). All the columns showed shear-failure mode during the tests, and the sheared plates of steel tubes yielded when the peak load had reached. The circular columns showed good ductility, while the square ones were just in opposite. Based on the analysis results, a simplified shear strength model for both circular and square columns is proposed, in which the relationship between cyclic shear strength and lateral drift ratio of the columns and the shear-resisting mechanisms for both shear and hoop stresses of the tube are considered.