Nonlinear Stability Analysis of Concrete-Filled Fiber-Reinforced Polymer-Tube Columns: Experimental and Theoretical Investigation

This paper presents experimental results and theoretical analysis for buckling responses of concrete-filled fiber-reinforced polymer (FRP)-tube (CFFTs) columns. The purpose of the analysis was to understand the effect of the slenderness ratio on the critical buckling load of axially loaded CFFT columns. The effect of three parameters and the paratneters' interaction on the buckling behavior were investigated; namely:G the FRP tube thickness, concrete compressive strength, and slenderness ratio. The experimental program consisted of testing 22 circular CFFT columns with a total height ranging from 305 to 1520 mm (12 to 60 in.) and an internal tube diameter of 152 mm (6 in.). The experimental results showed that the uniaxial compressive strength of CFFT columns was reduced by 13 to 23% and increased the slenderness ratio from 4 to 20 depending on the three tested parameters. The analysis in this paper aimed to correlate the slenderness ratio of the CFFT columns to various material characteristics and geometric properties of the FRP tubes and concrete. It was found that a slenderness ratio of 12 gave a safe value for the design purposes. A more precise formula for the slenderness ratio, however; was proposed to control the buckling mode of failure.