Research On The Behavior Of Rectangular Concrete Short Columns Confined With BFRP Sheets

With the excellent performance of light, strong, anticorrosion and fatigue resistance as well as easy construction, FRP has been widely used in concrete reinforce area. However, the current research on aspect forms of FRP confined concrete column is mostly based on the circular column, and little on the square or rectangle column. And FRP type is mainly CFRP, GFRP and AFRP, less experimental study for BFRP confined concrete columns.Through 18 groups BFRP confined square and rectangular concrete column's axial compression test, the properties of BFRP confined concrete column has been worked and the stress-strain curve comes out. It works on the confined effect of confined volume, confined form, aspect ratio on the confined performance. The test shows that both of the full package and strip package has improved the bearing capacity of unconfined concrete, and it's about 6.1%~49.5%. What's more, the effect of the full package of BFRP is more outstanding than strip package. The improving range of confined by one ply of BFRP is lower than the two ply, which is also higher than the strip of BFRP. As the number of plies of the BFRP increases, the confined effect enhances. And the confined effect of strip is not as good as the full. When the aspect ratio is 1.0, the fcc/fc0 by one ply of BFRP and two ply of BFRP is 1.16 and 1.52. And when the ratio is 2.0, the fcc/fc0 is 1.08. The confined effect is the best when the aspect ratio is 1.0, while there is less effect with the ratio of 2.0. As the aspect ratio increases, the confined effect of BFRP decreases. The strength of one ply of BFRP and strip of BFRP also decreases as the aspect ratio increases, but the range is not so big. And the two ply of BFRP has the obvious decreasing tendency. With the increasing of aspect ratio, the square and rectangle columns of BFRP confined have certain size effect. According to the test result, the stress-strain relation considered the aspect ratio has beencorrection by regression analysis. For the FRP confined rectangle concrete column, the stress-strain curve will have two kinds by confined form. One of the stress-strain curves is monotone increasing double linear curve and another is single peak point of the parabolic curve. The initial phase, both curves are approximated to the unconfined concrete column. When achieve peak point, the first curve into slope relatively low approximate line, and keep rising until the end, which shows a strong plastic strengthening characteristic; the another curve drabs down until the end, which shows the weak plastic strengthening characteristics.Based on the ANSYS, the BFRP confined square and rectangular concrete column has numerically simulated, in depth study of BFRP confined concrete column mechanical properties. Research shows that, selecting the appropriate Finite Element Model, can be used to simulate the mechanical properties of BFRP confined concrete.