Seismic Rehabilitation of Deficient Exterior Concrete Frame Joints

TLDR

The study compared the performance of rehabilitated beam‑column joints to existing pre‑seismic code joints to evaluate rehabilitation techniques. Six beam‑column subassemblies with nonductile detailing were quasi‑statically loaded; three with inadequate anchorage were reinforced with CFRP sheets, and three lacking steel ties were strengthened with GFRP jackets and steel rods or plates. Rehabilitation techniques eliminated brittle joint shear and steel bar bond‑slip failures, resulting in ductile beam hinging.

Abstract

The performance of rehabilitated reinforced concrete beam-column joints was compared with the response of existing joints designed to preseismic codes to assess proposed rehabilitation techniques. Six beam-column subassemblies with nonductile reinforcement detailing were tested. The joints were subjected to quasi-static load that simulates seismic forces. The first three specimens had inadequate anchorage length of the bottom beam bars. Two of them were strengthened by using carbon-fiber-reinforced polymer sheets attached to the bottom beam face and then tested. The other three specimens had no steel ties installed in the joint zone, in addition to inadequate anchorage length of the beam bars. Two of the beam-column joints were strengthened by glass-fiber-reinforced polymer jackets of the joint zone and steel rods or plates. The rehabilitation techniques were found effective in eliminating the brittle joint shear and steel bar bond-slip failure modes, and ductile beam hinging instead occurred.