Experiment Research On Axial Behavior Of Circle CFRP-steel Composite Confined Concrete Stub Columns

CFRP material has the property of high strength, light weight and well corrosion resistance, but CFRP tube filled concrete column need complex method in new buildings. Then tie CFRP outside the thin-walled steel pipe and use the steel pipe as templates of the CFRP. With this method can take the CFRP into new building in spend less. In this thesis, experimental research and theoretical analysis have been carried out for the circle CFRP-steel composite confined concrete stub columns The main research work are as follows:(1)Twenty-four circle CFRP-steel composite tube confined concrete short columns and four circular tube confined concrete columns under axial compression were tested. The main variable parameters were the aspect ratio, concrete strength and floors of CFRP. There were two: CFRP fracture damage: the break of CFRP and the shear failure of the core concrete. Taken analysis of load-deformation curve, load-CFRP circumferential strain curve and load-stress curve of the steel pipe. The results showed that with multiplied CFRP can provide the strength and the axial deformation of the core concrete, also the CFRP could change the stress development of the steel pipe, make it yield before the bearing capacity.(2) The core concrete stress- strain curves were analyzed, and obtain three forms: two line with ascending ends, two lines with horizontal and parabolic. Clear physical meaning curve feature point. Proposed a limit value of the strength of the constraint method. It defined the strong or weak of the constraint concept. When the coefficient is greater than the limit value,it was strong constraint, either it was weak constrain. Summed up the typical FRP confined concrete confined concrete column uniaxial stress-strain model. Design models and analytical models can be used to establish a composite tube confined concrete stress- strain model.(3) The use of finite element software ABAQUS simulation round CFRP- steel composite pipe constraint concrete stub columns were simulated in good agreement with the experimental results. Analysis of the applicability of capacity calculation method based on damage model oblique section and bearing capacity calculation method based on the total cross section crushed destruction.