SUSTAINABLE STRUCTURES. SEISMIC TYPE LOADING BEHAVIOR OF REPAIRED REINFORCED CONCRETE HYBRID JOINT

The behavior under lateral loading of a different type of hybrid moment frame joint composed of prefabricated reinforced concrete members assembled by non-adherent post-tensioned strands and having special ductile reinforcement in the beam-column connection zone is considered. This innovative design of hybrid joints, also called modified special hybrid joints in order not to be mistaken for the special hybrid moment frame joint, which respects the provision of ACI T1.2-03 standard, permit a simple repair procedure. The main difference between the special hybrid moment frame joint and the modified special hybrid joints consists of the special reinforcement connection detail. The former detailing allows the special reinforcement to be debonded only on two limited length zones at the interface of column-beam joint. The latter, the special reinforcement is bondless with respect to both column and beams and is fixed only at its ends. The modified special hybrid joint provides some important sustainable capacities, including one, which is in the background of this study, namely the simple and costless repair possibility of structures when damaged after a strong ground motion. The paper presents the results of a full scale repaired modified special hybrid joint tested under alternate horizontal ascending loading. The initial test was carried out up to a storey drift of 0.025, with respect to the actual structure, according to the Romanian seismic code allowable drift. The repaired specimen test was performed subjecting it to alternate horizontal ascending loading, but the second time, up to a storey drift of 0.035, with respect to the actual structure. Main results are presented and also discussion of the special reinforcement control of the joint behavior is revealed.