Upgrading Ductility Of RC Beam-column Connection With High Performance FRP Laminates
Free (open access)
M Z Kabir, H R Ashrafi & M N Varzaneh
Upgrading ductility of RC beam-column connection with high performance FRP laminates M. Z. Kabir, H. R. Ashrafi & M. N. Varzaneh Dept. of Civil Engineering, Amirkabir University of Technology, Tehran, Iran Abstract Strengthening and retrofitting of the reinforced concrete beams, which have been designed and built in the past, is one of the most important issues in structural engineering. In this study, reversal loading represents seismic excitation. The criterion for upgrading a RC joint against such loading is increasing its strength and ductility. Using composite fabrics does such enhancement. In this direction, FEM is adopted to analyze the problem. The non-linearity of concrete material, such as tension cracks and compression crush, are included. The steel bars behavior is considered as bilinear elasto-plastic, and Tsai-Wu criterion is used to control FRP failure. 8-Node solid element, 3-D link element, and layer shell element are used for modeling of concrete, steel rebar and FRP laminate, respectively. Both of the as-is and the retrofitted comer joints are subjected to quasi-static cyclic loading, and their performance is investigated and compared with each other, in terms of peak lateral load capacity, ductility, moment-rotation diagram, crack patterns and cracks width. The stacking sequence of FRP laminates is (45,- 45),, and it is made from Glass/Epoxy materials. The results are presented in terms of load-deflection curves and hysteretic energy loops. The load-deflection curves, for both as-is and strengthened beam- column connections, are studied in details, and the influence of using the composite fabrics on continuity of joints, smearing the cracks and limiting their sizes, are considered. The behavior of retrofitted joints is significantly improved in terms of moment bearing capacity, ductility, axial load, and drift.