Strengthening of edge reinforced concrete beam-column joints using steel elements

Detailing of beam-column joints on the edge columns of the reinforced concrete (RC) structures needs extra attention since the edge face is not naturally confined by surrounding beams. Inadequate detailing of transverse reinforcement, may cause the structure partially or completely collapse during an earthquake due to a brittle joint mechanism. Present experimental research aim to develop a strengthening method for edge beam-column joints which can convert joint mechanism into a desired ductile beam mechanism. Half scaled, one reference and 12 strengthened specimens with steel elements were prepared by paying attention for constructability in real conditions. Thus, the joint region was considered together with the surrounding columns, beams, and slab, and then tested under the loading conditions on each member that simulates an earthquake. Reference specimen was constructed with proper detailing and showed the expected favorable ductile beam mechanism. Among the tested strengthening methods, when adequate active confinement and shear resistance was provided by threaded steel rods in combination with steel shapes, desired reference specimen behavior was achieved in terms of strength, ductility, stiffness, and energy dissipation.