Plastic hinge relocation in concrete structures using the double-slotted-beam system

Several plastic hinge relocation techniques were proposed in the past few decades to avoid the congestion of the transverse steel at the joint, avoid strain penetration into the joint, and maintain the strong-column weak-beam behavior. The challenging aspect of these designs is the level of accuracy in predicting the center of rotation of the beam element, which is a necessary component in the seismic design of reinforced concrete frames. In this research, a newly developed concrete beam-column connection called the double slotted beam (DSB) was developed and used to relocate the plastic hinges in concrete frames, with a high level of accuracy in controlling the location of the center of rotation. Two vertical slots made at the top and bottom fibers of the beam member were introduced in the DSB system to control the location of the center of rotation. The plastic hinge was relocated by moving the vertical slots away from the face of the column. Experimental evaluation of large-scale DSB connections with and without relocated vertical slots showed the excellent performance of the system in achieving high drift capacities, non-tearing action, minimal concrete damage, and reduced bond deterioration in the joint.