Deformation Limits of Reinforced Concrete Columns and Their Experimental Verification

Abstract:

Parameters affecting the failure modes of reinforced concrete (RC) columns were investigated using low frequency cyclic loading experimental data from 469 reinforced concrete (RC) columns. A method using shear span ratio and moment shear ratio as parameters was proposed to classify the failure modes of RC columns. With reference to the current codes for seismic design, the performance states of RC columns were divided into seven levels. And the method for determining the deformation limits of these levels were put forward. The proposed method was based on three key performance points (point of yielding, point of losing 20% load capacity, point of losing bearing capacity) of the forcedisplacement backbone curves. Regression analyses of deformation limits of RC column, considering multiple combination of parameters, were performed using the collected test data of 469 RC columns, and deformation limits of RC columns of different failure modes were put forward using the most statistically significant regression formula. The proposed deformation limits were then evaluated using fragility analysis method. Finally, quasistatic tests on 11 RC columns were conducted and used to verify the proposed deformation limits. The results show that the accuracy, the discreteness and the failure probability of the deformation limits are all within reasonable range.