Experimental Investigation of Axial Compressive Behavior of Large-Scale Circular Concrete Columns Confined by Prestressed CFRP Strips: Fid-Bau Portal

Experimental Investigation of Axial Compressive Behavior of Large-Scale Circular Concrete Columns Confined by Prestressed CFRP Strips

Zhou, Changdong / A., Siha / Qiu, Yikun / Pan, Qinglong

Abstract

One important application of fiber-reinforced polymer (FRP) composites is providing confinement for concrete columns. Utilization of prestressed FRP sheets can relieve stress hysteresis through active confinement. And most investigations focus on small size concrete columns, but it is unclear whether the models that developed from small-scale cylinders are appropriate for large-scale columns due to the size effect. This paper evaluated the axial compressive behavior of large-scale circular concrete columns confined by lateral prestressed carbon fiber-reinforced polymer (CFRP) strips. A total of 10 large-scale columns were tested, and the size of the specimen was 800 mm in diameter and 2,500 mm high. These specimens included one unconfined column, seven columns actively confined by prestressed CFRP strips, and two columns passively confined by externally bonded CFRP strips. Including different strengthening methods, the influences of various prestress levels and different strip spacing were considered in this experiment. The test results indicated that, considering reinforcement effectiveness, axial load-bearing capacity and ductility of large-scale columns confined with prestressed CFRP strips were improved significantly. A polynomial stress-strain model is proposed based on the experimental results, and this model could be used to estimate the axial compressive behavior of large-scale concrete columns confined by prestressed CFRP strips.