Lateral Strain-To-Axial Strain Model for Laterally Prestressed Concrete-Filled FRP Tubes

Concrete-filled FRP tube (CFFT) columns have recently gained significant research attention, with a number of experimental studies identifying significant benefits of using highstrength concrete (HSC) to produce high-performance CFFT columns. A recent experimental investigation revealed that prestressing the fibers in the fiber reinforced polymer (FRP) confining shell leads to significant improvements in the axial compressive behavior of HSC-CFFTs. This paper reports the findings from an analytical investigation into the lateral strain-to-axial strain relationship for prestressed HSC-CFFTs. This understanding of the lateral strain-to-axial strain relationship is of particular importance for prestressed CFFTs due to the influence of the additional lateral prestrain. Initially a database that consists of 23 aramid FRP- (AFRP) confined HSC cylindrical specimens with lateral prestress of up to 7.3 MPa is presented. Based on close examination of the experimentally recorded data, an expression to predict the lateral strain-to-axial strain relationship for prestressed HSC-CFFTs is proposed. The comparison of the proposed model predictions with the experimental test results for specimens prepared with prestressed FRP tubes shows good agreement.