Cyclic load tests on six reinforced concrete (RC) exterior beamcolumn
subassemblages simulating joints of buildings constructed
before the 1970s, with nonoptimal reinforcing details to resist
earthquakes, are described. The exterior beam-column joints were
reinforced by plain bars and lacked transverse reinforcement, and
the longitudinal beam bars were poorly anchored. Two of them had
inadequate beam top reinforcement. All of the beam-column joints
were also tested after the upgrade, except one, which was upgraded
and then tested for the first time. The proposed upgrade techniques
were aimed at providing an effectual anchoring to the beam longitudinal
bars and at increasing strength and stiffness of the beamcolumn
joints. As expected, the performance of reference specimens
(without upgrade) was found to be unsatisfactory in terms of lateral
load capacity and stiffness. The improvement in the performance of
the upgraded specimens is demonstrated.
