Performance Of Axially Loaded Short Rectangular Columns Of Different Strength Concrete Wrapped With CFRP Sheets

After the analysis of the current progress in research,Performance of axially loaded short rectangular columns of different strength concrete wrapped with CFRP(Carbon Fiber Reinforced Polymer,referred to as the CFRP)sheets were studied by experiment and numerical simulation.Six confined columns and one controll column were desiged and tested.The influence of concrete strength grade on the axial compression performance of columns was studied.The damage process and mechanism of the confined concrete short columns are studied in the test.As the strength of concrete increases,the peak load of the reinforced column increases significantly.The initial slope of the load-deformation curve of columns increases,and the deformation increases under the peak load and ultimate load.When concrete strength is same,that increasing CFRP layer can improve the confinement effect,especially for the low-strength concrete,the failure modes of tested confined columns transfered from weak confinement to powerful confinement.The finite element software ABAQUS is used to simulate the rectangular column wrapped with CFRP and got good accordence with test results.It shows that CFRP has little effect on the peak load of high strength concrete columns.The circumferential CFRP strain along the column ring is well not distributed.The axial concrete stress distribution on the transverse section of the concrete column is also not uniform.The steel can improve the surrounding axial concrete stress,and the range of improvement is enhanced with the decrease of concrete strength.Based on the collected test data,this article obtained the relationship between threshold which distinguishing between weak confinement and powerful confinement and concrete strength by regression method,and found that the threshold value increases linearly with the concrete strength.Based on past research results,rectangular column can be simplified to the equivalent cylindrical by considering the parameters of cross section shape and banding spacing,and obtained that formula of equivalent lateral confined column strength is applicable for rectangular column.It is found that test results of this paper are in good agreement with relationship formula obtained by regression method.