Seismic Behavior of High-Strength Concrete-Filled FRP Tube Columns

This paper reports on an experimental program that investigated the seismic behavior of high-strength concrete (HSC)-filled fiber-reinforced-polymer (FRP) tubes (HSCFFTs), designed to perform as building columns. Five square and one circular concrete-filled FRP tube (CFFT) columns were tested under constant axial compression and reversed-cyclic lateral loading. The main parameters of the experimental study were the axial load level, column cross-sectional shape, concrete strength, amount and type of FRP confinement, and FRP tube corner radius. Examination of the test data resulted in a number of significant conclusions with regard to the influence of the investigated column parameters on the performance of CFFT columns. Of primary importance, the results indicate that square HSCFFT columns are capable of developing very high inelastic deformation capacities under simulated seismic loading. The results also indicate that increasing the FRP tube corner radius up to a certain threshold leads to a significant increase in column lateral drift capacities. By contrast, increasing the corner radius beyond that threshold value provides no additional improvement in the hysteretic behavior of square CFFT columns. The influence of the cross-sectional shape is found to be significant, with the circular CFFT exhibiting a larger lateral drift capacity compared with the companion square CFFTs. A set of comparable columns from previous studies has also been included in the discussion to clarify the influence of each parameter on the column behavior. The results of the experimental program are presented together with a discussion on the influence of the main parameters on the seismic behavior of CFFT columns. (C) 2013 American Society of Civil Engineers.