Shear Strength Design and Tests of Circular Reinforced Concrete Columns Confined with a FRP-Wrapped Spiral Corrugated Tube

This study is conducted to investigate the shear strength of FRP-Wrapped Spiral Corrugated Tube (FWSCT) confined circular concrete columns. In order to study the shear strength of the Spiral Corrugated Tube and the FRP jacket, two shear strength models (UCSD shear model and residual shear model) are adopted in this analytical procedure. In this experimental program, two FRP-Wrapped Spiral Corrugated Tube (FWSCT) Circular Concrete Columns with different amount of FRP confinement were tested under cyclic lateral loading with a constant axial load level. The main variable was the confinement ratio of the FRP jacket, which can be controlled by wrapping different number of FRP sheets around the Spiral Corrugated Tube. Two columns, FWSCT-1 and FWSCT-3 were designed based on a reference column, FWSCT-0 (Wu 2015), which confined by only a spiral corrugated tube with 0.4 mm thick and 1940 mm tube length. FWSCT-1 and FWSCT-3 were wrapped by additional one-layer and three-layer of Glass Fiber-Reinforced Polymer (GFRP) jackets around a spiral corrugated tube, respectively. Test results showed that the brittle shear failure in specimen FWSCT-0 is improved by wrapping one-layer of the GFRP jacket as seen in the test of specimen FWSCT-1. Specimen FWSCT-1 failed at 4% story drift, resulting in flexural-shear failure of column, while specimen FWSCT-3 failed at 7% story drift, resulting in flexural failure of longitudinal bars.