Experimental Research On Large-Scale Square Concrete Columns Confined With Wrapped CFRP Under Axial Compressive

Fiber reinforced polymer(FRP) composites has become increasing used for the repairing and retrofitting of concrete structure. The widely used of FRP composites is due to excellent material properties, easiness of construction and excellent corrosion resistance. However, fundamental research, particularly on FRP confined large scale square columns, is limited. This is also the blind area of present study. Which restrict the development and application of FRP confined concrete columns.This paper based on a series of tests on seven groups of CFRP confined large-scale square concrete columns with different corner radius, the basic mechanical properties were obtained, such as the failure modes, compressive strengths, stress-strain relationships and the ultimate strain distribution of CFRP jacket. Compare with the experimental results of the smaller-scale specimens that have been published. the test results demonstrate that the confined strength increases according to the corner radius increasing except for the specimens with sharp corner. All of the specimens failed due to CFRP rupture and the fracture location occurred in the chamfer zone. So the phenomenon of the stress concentration is obvious. The confinement ratio, MCR, can response the effect of the specimens’ size well. The ultimate strains measured on the CFRP jackets are about 35% less than the ultimate strain tested by the coupon specimens, which is more serious than the smaller-scale specimens. The discrepancies between the predicted results of the existing strength models about CFRP confined square column and the experimental results of this work are obvious. It suggests that the size effect on the FRP confined square columns can not be ignored. This size effect need to be researched further. Collect the test results that have been published and summarize the current typical strength model of FRP confined square concrete columns. Evaluate the strength model through sum of error squares. On the basis of existing research, improve the strength model of FRP confined rectangular concrete columns and get a better results.Also this paper studied the material constitutive, element type ect, the ultimate compressive strength of FRP confined square concrete columns was done under different parameters by ansys program. Compared the test results with the calculation results of finite element analysis. This discrepancies are not obvious between them. It shows that selecting reasonable finite element model can better predict the mechanical performance, at the same time, using ANSYS to analysis the effect of the plies, the type of FRP. It is significant meaningful to reduce the amount of test and obtain more meaningful data by using ANSYS.