SEISMIC BEHAVIOUR OF EXTERIOR BEAM-COLUMN JOINTS WITH SQUARE SPIRAL CONFINEMENT

This paper presents the seismic behavior of exterior beam-column joints with square spiral confinement in the joint region along with different reinforcement detailing for anchorage of beam bars, confinement in joint and additional reinforcement in beam and column. The behaviour of specimen with square spiral confinement (SS) in the joint region without any additional reinforcement in beam or column is compared with SS1, SS2, SS3, SS4 and SS5. SS1 indicates specimen with beam longitudinal bars having inclined anchorage and SS2 is the specimen with additional inclined bars from column to beam. The specimen with additional beam bars and primary beam bars provided with round hook type anchorage is SS3. SS4 was provided with welded wire mesh in joint region alone whereas SS5 had welded wire mesh in beam and column region. The performance of the specimens are compared in terms of lateral load-displacement hysteresis loop, load ratio, percent of initial stiffness versus displacement curves, total energy dissipation, beam rotation at distances of D and 2D, strain in beam main bars and crack pattern. Among all the specimens, SS2 was the most effective considering all the parameters taken for comparison. It is concluded that inclined bars from column to beam over a specific beam length in SS2 can successfully move the plastic hinge away from the column face.