Displacement-based model to predict lateral drift capacities of concrete-filled FRP tube columns

It has been shown over the past three decades that fiber reinforced polymer (FRP) composite tubes offer an attractive alternative to conventional confinement reinforcement to enhance strength and deformability of concrete columns. Concrete-filled FRP tube (CFFT) columns have been shown to exhibit highly ductile behavior under simulated seismic loading, making them suitable for use in earthquake-resistant construction. For the design of CFFT columns in new construction there is need for a rational procedure that enables the prediction of lateral drift capacities of these columns. This paper presents such a procedure for displacement-based design of circular and square CFFT columns. The approach incorporates influences of experimentally observed confinement parameters while also including axial load level and lateral drift capacity as design variables. The expression derived as part of the proposed design procedure has been validated using available experimental data, and it has been shown that the predicted capacities are in good agreement with the experimental results.