The Experimental Studies On Behavior Of Concrete Short Columns Wrapped With CFRP Cloth Under Axial Compression

The used building is in order to meet the demand of sustainable development, is inevitably in need of repair and reinforcement, CFRP reinforcement is now one of the very popular form reinforcement. But in practical engineering of the widespread use of the column needed strengthening is rectangular section. This paper according to engineering, in both rectangular column section, and on the basis of not damage the quadrilateral column, with sides around central wipe out in a certain degree, will cement mortar rectangular section into circular arc the section tend to use the constraints, CFRP successfully. In the different strength grade of concrete, reinforced different quantity condition, to the original rectangular corner with rectangular section by section after the treatment of chamfer of circular arc form of mechanical processing section comparative performance analysis; In the regression turning point and constraint intensity FCP stiffness ratio of the beta j, limit the FCC and constraint intensity point thanηcurve between, on the basis of the rectangular section that corner and circular arc processs unity section stress-strain relationship expression.In this paper based on the former research, through to the 21 different sectional shape outsourcing carbon fiber (CFRP) cloth, concrete short column constraints axial compression experiment on specimens of its mechanical properties and nonlinear analysis and research.In CFRP constraints rectangular section and the concrete arc column section the inhomogeneity of the lateral strength, this paper introduced rectangular cross-section shape coefficient for Ks= 0.64; The rectangular cross-section shape coefficient, and on the basis of the circle, the diameter of the circular arc according to the maximum size of the string length, rectangular section the proportion between the relationship between the cross section, it is concluded that the circular arc of the section shape coefficient for the column Ks= 0.896; According to outsourcing fiber can provide the constraint is different, and through the analysis test the boundaries of constraint intensity and stiffness ratio j0 value constraints beta 4.89 and square corner section are j0 10.12 beta.According to literature [33] model considering stress-strain curve into two stages, this paper considers the initial stage of the elastic, stress-strain entire process is divided into three stages, with more accurately reflect the actual stress, strain stress state. This article will conerete stress-strain curve, that is the first stage of the axial pressure is 0.4 times the ultimate bearing capacity of the stress-strain curve when the first stage for concrete stress element equivalent strain curve-the first stage. The second phase is divided into 0.4 times to the limit bearing capacity of the ultimate bearing capacity of elastic stage, through the experiment data regression equations obtained. The third stage is the ideal linear elastic materials CFRP successfully constraints of strengthen or straight line by line soften stage, its starting point and end point for turning point for breaking point, introducing constraints than beta j and stiffness rigidity thanη, through the experiment data regression determined the starting point and the end of the characteristic value, and that the square corner section and the processing of arc section of the stress-strain relationship curve expression, and the test results are in good agreement with the compared.The analysis results show that the simple processing of arc, cross section was better than rectangular section column column, the ultimate bearing capacity can be improved to 2.83 times. The experiment analysis can be used as the actual reinforcement project economic index analysis of the reference, suggest that in engineering practice reinforcement rectangular column, should try to avoid using rectangular corner of the cross section shape, appropriate to take the processing section form circular arc.