Experimental Study Of Eccentrically Loaded BFRP Confined Circular RC Columns

Fiber reinforced polymer (FRP for short) is divided into carbon fiber reinforced polymer (CFRP for short), basalt fiber reinforced polymer (BFRP for short), glass fiber reinforced polymer (GFRP for short) and aramid fiber reinforced polymer (AFRP for short) in the type of material. FRP has a high specific strength (strength to weight radio) and a good corrosion resistance, so that it had been wildly used to reinforced concrete structures. Compared with other FRP, BFRP is a environmentally friendly composite materials because of inorganic and natural degradation. Although the elastic modulus of BFRP is less than CFRP’s, the tensile strength of BFRP is close to CFRP’s. Moreover, the price of BFRP is only one fifth of the CFRP’s.Reinforced concrete columns, which had been built in structures, need to be reinforced because there are so many factors that affect their safety and using function. For example, the design code is unreasonable in the early, the using function of structure has been changed, the damage because of long-term using, poor performance and inadequate bearing capacity because of the aging and construction defects, etc. As we know, FRP has so many advantages, such as light weight, corrosion-resistant, permeability-resistance and short work cycle, so that FRP is wildly used to strengthen reinforced concrete columns and it has broad application prospects. At present, a small number of the research on BFRP-reinforced concrete specimens is square columns, all of which are small size. There is not research on large size or cylinders specimens, which is reinforced by BFRP.In this paper, the mechanical properties of BFRP-reinforced eccentric pressured cylinder had been studied. There are seven columns, whose length are1800mm, would be studied. Among them, six BFRP-reinforced concrete columns, whose slenderness ratio (1/d) are6, and the seventh column is a contrast specimen, which is not reinforced. The effect of the eccentricity ratio and thickness of BFRP to the bearing capacity of columns, stress-strain relationship and deflection can be learned by changing the eccentricity ratio and thickness of BFRP. The main researches are as follows:BFRP-reinforced concrete columns with large size and eccentric compression are researched to eliminate the size effect and provide a reference for engineering applications.The test process, which includes test scheme, preparation work, pouring specimens; sample maintaining, wrapping BFRP, loading equipment and etc, had been introduced. Furthermore, the failure mode and destruction causes of specimens in axial compression, compression load with small eccentricity or large eccentricity had been analyzed.The effect of eccentricity and thickness of BFRP to the bearing capacity, deflection and ductility of eccentric compression columns has been researched. Furthermore, the stress-strain relationship, load-deflection relationship and load-bending moment relationship of BFRP-reinforced concrete columns under eccentric compression are researched to provide a theoretical basis for engineering applications.