Experimental Study Of Rc Exterior Beam Column Connections Retrofitted By Steel Plate And HAUNCH Under Earthquake

As the rapid development of the national construction industry,existing reinforced concrete old buildings have been designed against mainly gravity load,and are vulnerable to shear failure in beam-column connections under earthquake loads.Today,several research has been performed on the seismic behavior of RC beam-column joints,which play a key role in building,especially in frame structure.Over several decades,numerous domestic and abroad experimental and analytical studies have been performed and found that the columns and beams could also present significant rotational deformation,which induces a significant shear deformation and force in the beam-column joints,leading to shear failure.Especially,exterior beam-column connections might show brittle structural behavior due to the discontinuity of the beams,weak confinement of concrete inside the connections,and fragile shear resisting mechanism dependent on concrete tensile strength.According to the previous literature and analyzing the retrofit method of the beam column joints.This study developed several retrofit methods for RC beam-column connections with non-seismic details.Five half-scale RC exterior beam-column connections were fabricated and tested under cyclic loading simulation earthquake loading.The first connection was designed to be failed in shear and tested as the control specimen and steel jacketing with various shapes and sizes.Two different retrofit strategies were applied to a control specimen which considered the architectural characteristic in real buildings:steel jacketing and haunches retrofit solution.Through the analysis of all specimens by low cyclic loading test result data analysis,research on the performances and characteristics of the test specimens were investigated in various terms:damage and failure,load-drift relationship,dissipated energy,damping ratio,effective stiffness,and ductility.Experimental results showed that the retrofit methods of RC exterior beam-column connections compare to J-1 specimen,in the positive loading direction,the peak loads increased up to 26%.10%.12%.64%;Meanwhile,in the negative loading direction,the peak loads increased up to 11%、5%、8%、53%.In addition,the deformation capacity;and also reduced the shear deformation in the panel zone significantly compared to control specimen.In the steel jacketing retrofitted specimens,in the negative loading direction,the ductility coefficient increased up to 8.3%、11.1%、6.7%。The J-S2 structural behavior would be more ductile than J-1 specimen,in accordance with Chinese code for seismic design of building GB50011-2010.In general,except for J-H,the energy dissipation capacity of most specimens strengthened with steel jackets showed almost the same trend as that of J-1,but the dissipated energy of the retrofitted specimen J-H continued to increase up to 45%.At the elastic-plastic state,the damping ratios were around 0.035-0.087,to comply with related Chinese codes and standards.Steel plate would be confinement in the joint core concrete,it can increases strength and changed the failure mode of the specimen.Meanwhile,the development of inclined cracks in the joint core is delayed,so as to improve the ductility and energy dissipation capacity of the joint to avoid the joint occurring shear failure.It was feasible that ANSYS software could be used to speculate the actual carrying capacity of engineering for external beam-column joints with non-seismic details.However,which are available for retrofit reconstruction project design and construction method.The results of ANSYS analysis were consistent with the results of theoretical calculations,which were all less than the results of actual test data.