EXPERIMENTAL INVESTIGATION ON SEISMIC BEHAVIOR OF RC INTERIOR BEAM-COLUMN JOINTS WITH DIFFERENT BEAMS DEPTH

Current Design Codes for Reinforced Concrete (RC) interior beam-column joints are based on limited experimental studies on the seismic behavior of eccentric joints. To supplement existing information, an experimental study was conducted that focused on the effect of eccentricity of the deeper beams with respect to the shallow beams (an experimental study was conducted that focused on the effect of eccentricity from the vertical eccentricity between the axes of both beams). A total of eight one-third scale interior joints with different depth beams were subjected to reversed cyclic loading. The primary variables in the test specimens were the amount of joint transverse reinforcement and the cross section of the shallow beams. The overall performance of each test assembly was found to be unsatisfactory in terms of joint shear strength, stiffness, energy dissipation and shear deformation. The results indicated that the vertical eccentricity of spandrel beams in this type joints led to lower capacity in joint shear strength and severe damage of concrete in the joint core. Increasing the joint shear reinforcement was not effective to alter the failure mode form joint shear failure to beam yielding which is favorable for earthquake resistance design, whereas it was effective to reduce the crack width at the small loading stages. Based on the observed behavior, the shear stress of joint core was suggested kept as low as possible for a safe and practical design of this type joints.