rc beam–column connections retrofitted by steel prop: experimental and analytical studies

This paper studies the efficiency of a proposed retrofit technique to boost the seismic behavior of beam–column connections in existing deficient reinforced concrete (rc) moment frame systems with the consideration of constraint conditions such as the height of beams, using analytical, experimental, and numerical methods. the proposed retrofit method, called the “single steel prop and curbs”, consists of a diagonal steel prop element and two steel curbs that to the beam and column are laterally mounted. the internal force diagrams of the retrofitted exterior beam–column connections by analytical formulations are investigated and design strategies for promoting the efficiency of the single steel prop to achieve the expected efficiency proposed. to assay the validity and reliability of the proposed analytical procedure, experimental and numerical assessments were also conducted independently. therefore, four deficient rc beam–column connections by single steel prop were retrofitted using three different cross-sectional areas and revival sheets and then accompanied by a control specimen subjected to cyclic loading. next, numerical models were calibrated in abaqus software. finally, by derivation of the props’ average axial force from experimental and numerical results, the beam shear coefficient, β, is calculated based on the analytical relations. these results confirmed good conformity between the experimental and numerical outputs as well as reliability of the analytical formulations. also, the output results indicated that the retrofitted specimens had 53–78% bearing capacity and 146–217% dissipated energy more than the control specimen.