FAILURE MECHANISM AND DAMAGE ANALYSIS OF SPACE CORNER JOINTS OF SRC L-SHAPED COLUMNS UNDER CYCLIC LOADING

To study the failure mechanism and damage evolution process of space corner joints of steel reinforced concrete (SRC) special-shaped columns, 9 specimens were designed to perform low cyclic loading tests. Four parameters were considered, which were the column section steel form, the axial compression ratio, the load angle and the beam form. The crack development pattern was observed, and the failure mechanism was revealed. The load-strain hysteretic curve, the shear deformation at joint core areas and the mean curvature of beam cross-sections were obtained. Based on the law of energy conservation, the damage characteristics of specimens were studied, and the influence of varying parameters on damage accumulation were analyzed. Results indicate the failure patterns of space corner joints of SRC special-shaped columns are bending and shear-diagonal compression, and are accompanied by torsion and adhesive failures. Most steel at joint core areas has yield, and with the increase of the column limb angle, the steel strain, shear angle and mean curvature of beam cross-sections decrease. The cumulative damage index amongst all specimens is between 0.69 and 0.84 at the state of failure, and that of specimens with channel steel truss is the largest at various levels of displacement. The damage of 45° loading specimens with solid web steel is more severe than that of 30°. Compared with 45° loading specimens, the cumulative damage of 0° loading specimens at various levels of displacements is increased by up to 30%. The effects of axial compression ratio on specimen damage are comparatively insignificant. Compared with specimens with steel beams, the cumulative damage of specimens with steel reinforced concrete beams has a greater degree of ease.