THE HYSTERETIC BEHAVIOR OF R/C COLUMNS BASED ON THE CONTRASTING TESTS UNDER CONSTANT AND VARYING AXIAL FORCES

The variation of axial force of the frame column under earthquake excitation is discussed first. Based on the comparison of hysteresis curves acquired by the column's cyclic loading test under constant and varying axial forces, the "equivalent hysteresis" gained at every 揾alf cycle of axial force?is used to modify the hysteresis envelope. In terms of the integral step, the "equivalent cumulating hysteretic axial force" is used to adjust the deteriorated coefficient of cumulating strength and hence to modify the reloading path. With the suggestions given by the authors, it is more efficient and convenient to reflect the influence of the whole history of axial forces on the hysterestic behavior of columns under varying axial forces. The results are also helpful to the improvement of the reliability of nonlinear dynamic response analysis of reinforced concrete (R/C) member-typed structures.