EXPERIMENTAL STUDY ON BOND SLIP BEHAVIOR BETWEEN SHAPE STEEL AND CONCRETE IN SRC COLUMNS UNDER CYCLIC REVERSED LOADING

This paper studies bond slip behavior of steel reinforced concrete (SRC) columns under constant axial load and cyclic reversed horizontal load. With strain gauges and slip transfers embedded on flanges of the shape steels, the test generates hysteretic and skeleton curves of slip against horizontal load. The distribution of bond stress and slip along columns are also obtained. Influence of load cycle number on bond stresses and slips are analyzed, and calculating formula for bond degeneration is presented. Test results show that the hysteretic curve of slip against horizontal load is chubbiness without pinching. At the stage before ultimate horizontal load, bond stress is distributed in parabola along columns. At load-descending stage, the maximum bond stress occurs at the top of columns, and bond stress at the bottom of columns decreases to zero due to the yielding of steel flanges, leading to the occurrence of zero-bone zone along columns. In the whole stage of loading, the interior slip between shape steel and concrete is exponentially distributed along columns. With the increase of load cycle number, bond stresses along columns gradually decrease, but slips gradually increase, demonstrating bond degeneration.