Two-way Shear Strength Test And FEM Analysis On Reinforced Concrete Frame Columns Retrofitted With CFS

The bilateral shear behaviors and the bilateral seismic properties of reinforcedconcrete frame columns strengthened with CFRP sheets under the oblique andhorizontal cyclic loading haven't been studied by researchers. The research on themhas an important significance because the concrete members strengthened with CFRPsheets are subjected to the actions in the two axial directions under the earthquake inthe seismic areas. On the base of damage test of 4 RC frame columns retrofitted with CFS under theoblique and horizontal cyclic loadings, this paper studied crack development, thedeformation, the hysteretic behavior, the failure mode and the damage mechanism, etc.with the method of the nonlinear finite element on the base of analysis of the existingrelevant research on the concrete structures strengthened with CFRP sheets, which isfinished through a series of damage tests of concrete members strengthened withCFRP sheets under the obliquely and horizontally cyclic loadings. The aim of thepaper is to provide a base to study, design in the future. The experimental results indicate that the CFS works like links. By bonding theCFS exteriorly, the failure mode of the members changes from the shear failure to theflexural failure. The shape of Load-Deflection hysteresis loops is reverse S shape. Themembers' energy-consuming capacity is more and more small with the loading angelchanges from 0°to 90°. Compared with members without CFS, retrofitted withCFS can enlarge the crack strength and the ultimate strength, also it can improve themember's seismic properties. On the basis of anslysis and research of many shear models, a new model namedtwo-way truss-arch model is presented which can explain two-way shear of RCFcolumns retrofitted with CFS. The calculation results make good agreement withexperimental results, which shows the model is properly. The regression ofexperimental results shows that the correlationship curve of two-waycompression-bending of RCF columns is an elliptoid curve, the curve characteristicindex of which is 3. On the base of the plastic theory with a mixed modeling of the structure, RCFcolumns strengthened with CFS under oblique and horizontal cyclic loadings isanalysised by three-dimensional nonlinear finite element method. With the programsdeveloped from ANSYS by using APDL, the complete failure procedure of reinforcedconcrete members strengthened with CFS is obtained. The comparison between thenumerical results and experimental results stated that the analysis approach is validand economic.