عنوان مقاله [English]
At several last decades, the researchers have suggested various methods for strengthening of reinforced concrete beam- column connections that each of them has deficiencies and advantages. Each proposed method has particular advantages such as increasing capacity, stiffness, material costs, construction process cost and professional labor, so due to new required property of deficient structure, one of those method can be applied. This \ paper \ presents \ an \ experimental \ investigation of \ strengthening effects on the external corner weak (with low \ strength concrete and \ low height \ of beam ) reinforced \ concrete (RC) beam-column connections by suggestion method of steel elements (steel prop \& curb) subject to cyclic loading. Three half scale RC beam-column connections with low strength concrete were prepared and casted, including of two un-strengthened reference connections with different height of beam (low and standard height), and another with low height of beam that was strengthened by suggested system of one direction steel prop and curb that then every sample were subjected to cyclic loading. The experimental results and observations indicated that by 25\% reduction of height of connection beam, caused to reduction in stiffness, increasing the lateral displacement of beam of connection and also reduction 25\%, 33\% and 26\% in ductility, bear capacity and energy absorption respectively. Also, it was determined that the suggested system of strengthening, by increasing strength and decreasing stiffness degradation, and raising the nergy bsorption of RC weak beam- column connection, can minimize the damages due to cyclic loading in the beam to column joint and panel zone. It can cause to development behavior of weak RC connection, as the performance of weak RC connection was upgraded to limit of behavior of connection with standard beam. Therefore, this suggested system with any different sizes and angles, corresponding to the required strength and stiffness can be easily applicable for any deficient RC beam-column connection in RC frames.