EFFECT OF AXIAL LOAD ON THE SHEAR-TRANSFER MECHANISM DURING SHEAR DAMAGE PROGRESS IN R/C COLUMNS

Recent approaches to the design of reinforced concrete members have paid attention not only to shear failure as a primary cause of collapse, but also to shear damage from the viewpoint of serviceability and durability. Tests were performed on RC columns having axial load ratios of 0 to 0.3, and shear reinforcement ratios of 0.29% and 0.63% in order to study the influence of axial load and shear reinforcement upon the shear-transfer mechanism while shear damage was in progress. Resistance against shear damage increases with an increase in shear reinforcement, but the shear-transfer ability, due to the concrete contribution, decreases with an increase in shear reinforcement and axial load. A method for evaluating shear damage has been proposed based on the shear-transfer mechanism of concrete and reinforcement. FEM analyses have been also carried out to verify the transition of the shear-transfer mechanism estimated by the proposed method.