Axial compressive behaviour of circular CFFT: Experimental database and design-oriented model

Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted

significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to

corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and

the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection

criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been

compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual

confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive

strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design

oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT

columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute

Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD)

as compared to other available strength and strain enhancement ratios of circular CFFT column models. The

predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength

and strain enhancement ratios investigation results in the compiled database.