Research On Behavior Of CFRP Confined High-strength Concrete Filled Steel Tube Stub Columns Under Axial Compression

CFRP high-strength concrete filled steel tubular column, derived from concrete filled steel tubular column, is a kind of composite structure combined by three materials by using the CFRP past on the peripheral of the concrete filled round steel tubular column. High-strength concrete-filled steel tube technology is an economic and effective measure to solve "fat column‖ problem in reinforced concrete high-rise buildings and to increase the spanning capacity of bridge structure. However, using of high-strength concrete will result increased brittleness in CFST columns, while th e application of high-strength thin-walled steel tube will make local stability issues. Based on the above engineering background, the state of CFST and CFRP confined CFST research was compared, and the concept of CFRP confined high strength concrete filled steel tube columns were proposed in this paper. Finally, the analytical method and research objective of CFRP confined CFST columns were referenced.There are experiment and theoretical analysis on the mechanics of the CFRP high-strength concrete-filled steel tube column, master its design method to provide reference for engineering practice.This paper carried out the following several aspects:(1) 6 CFRP confined normal strength concrete filled round steel tube columns and 6 CFRP confined high-strength concrete filled round steel tube columns were tested to axial pressure by the experimental parameters included diameter-thickness ratio, concrete strength and CFRP layers. The results showed that both of the CFRP confined normal strength concrete filled round steel tube columns and CFRP confined high-strength concrete filled round steel tube columns failed due to shear failure of core concrete while the diameter-thickness ratio is large. The CFRP confinement index has different effects on them.(2) Through multiple regressions of experimental data, we get the confinement index of the short column, and deduce the calculation formula for the bearing capacity of CFRP high-strength concrete-filled steel tube column on axial pressure; Base on a reasonable assumption of stress state of the CFRP tube, steel tube and core concrete on ultimate. Deduce the bearing capacity of CFRP high-strength concrete-filled steel tube column on axial pressure through solid mechanics method.(3) In order to make up for the drawback of insufficient of the test specimens, a finite elements analysis model of CFRP confined concrete-filled steel tube short column was developed through the PE software ABAQUS. The predicted results are in good agreement with experimental results, and can b e applied to the future mechanics performance analysis.(4) Through VE principle and method, analyzing economic of CFRP confined concrete-filled steel tube short column.