Cyclic performance of retrofitted reinforced concrete beam–column joints using steel prop

This paper investigates the cyclic experimental behavior of damaged exterior reinforced concrete beam–column joint specimens retrofitted with the proposed technique using steel elements called steel prop and curb. The technique is usable for local and global strengthening of reinforced concrete frames. Four half-scale RC joints were tested under the cyclic loading; two control specimens with the different beam heights were loaded up to their ultimate strength and this was followed by retrofitting of these damaged specimens as new specimens and tested again under the same loading system. Experimental results showed that the 25% reduction of beam height due to construction mistake caused increasing in deflection of joint beam, decreasing of ductility and also 33% and 26% decreasing in bearing capacity and energy absorption, respectively. The ultimate load was increased up to 80% and the rigidity decreased degradation of retrofitted damaged joints was significantly in the proposed retrofitting system. And also the energy absorption was enhanced and the cracks were minimized due to a new lateral loading in the beam–column joint region in this upgrading method.

► Effective to confine concrete connections and transfer force to RC structure.
► Improvement of strength, energy absorption, rigidity.
► Decreasing horizontal drift up to permissible limit stated in Design codes.
► Usable to strengthen deficient frames with reduced heights and concrete strength.