Evaluating Method of Deformation at Losing Point of Axial Load Carrying Capacity of RC Columns

RC buildings often suffer severe damage, including pancake-type total collapse, during strong earthquakes. The objective of this study is to find a way to prevent pancake-type collapse in old RC buildings during strong earthquakes. In 2006, the authors conducted static loading tests on RC column specimens failing in shear and proposed an equation for evaluating the lateral deflection angle at the losing point of axial load carrying capacity. In this study, first, the equation was reexamined using data for specimens with a wider range of parameters. Comparison with this new experimental data showed that the equation is effective for conservative evaluation. Second, the applicability of the equation to RC columns failing in flexure was also examined. For this, the lateral deflection angle of columns failing in flexure was obtained by adding the flexural component to the shear component proposed already. The proposed method was found to be effective. Finally, a trial evaluation of the axial deformation at the losing point of the axial load carrying capacity was performed, and the equation was found to be effective, though with some exceptions.