EXPERIMENTAL STUDY ON SEISMIC BEHAVIOR OF REINFORCED CONCRETE PIPE COLUMNS WITH A LARGE CROSS SECTION SIZE AND THINNED WALL

Four 1/8 scale specimens are tested under the low-reversed cyclic loading to investigate the seismic behavior of reinforced concrete pipe columns with a large cross section size and thinned wall. The influenencing factors including the axial compression ratio, the thickness to diameter ratio and the reinforcement ratio are analyzed and assessed. The hysteretic curves, skeleton curves and their characteristic values, the displacement ductilities and failure modes are analyzed. The formula prescribed by Code for design of concrete structures (GB50010-2002) is employed to calculate the flexure bearing capacity of the specimens, showing that the current code tends to underestimate the flexure bearing capacity. To improve the calculation accuracy, a formula for calculating the flexure bearing capacity of reinforced concrete pipe columns with double-row longitudinal bars is suggested. Finally, a FEM analysis by using ANSYS is performed, and good agreement with the test results is observed. This study also shows the common failure mode of reinforced concrete pipe columns with a large cross section size and thinned wall is bending failure, and axial compression ratio has great influence on the ductility of the pipe columns.