Cyclic testing of exterior beam-column joints with varying joint aspect ratio

To examine the effects of joint aspect ratio (beam depth to column depth ratio) on shear strength and required amount of transverse reinforcement in exterior beam-column joints, 14 joint specimens were tested under reversed cyclic loading. The main experimental parameters were the joint aspect ratio, the amount of transverse reinforcement, and the anchorage types of beam bars (hooked and headed bars). The test results indicate that, for a joint aspect ratio equal to or less than 1.0, all joints showed typical flexural behavior. Even transverse reinforcement was reduced to two-thirds of the transverse reinforcement required by ACI 352R-02; the hysteretic behavior and strengths of the joints were similar to those of the joints designed in accordance with ACI 352R-02. For a joint aspect ratio equal to or greater than 2.0, nominal strengths of joints could not be developed and joint shear failure occurred where the requirements of ACI 352R-02 were satisfied. From the analysis of measured shear strengths of the joints, it is suggested that the shear strength factor of ACI 352R-02 is reduced as the joint aspect ratio increases, if the joint aspect ratio is higher than 1.65. The test results also indicate that there was no significant difference between anchorage types of hooked or headed bars.