Compressive Behavior of GFRP Reinforcing Bars and GFRP Reinforced Concrete Short Columns Considering Buckling of Longitudinal Bars

Abstract

Currently, GFRP bars are widely used in construction, especially in areas with a high risk of steel corrosion from chloride. GFRP bars have a prominent property of higher tensile strength than steel, but their elastic modulus is 3.3 times lower than steel. This results in reinforced concrete structures with GFRP bars having inferior behavior compared to reinforced concrete structures with steel. If used to reinforce tensile stress in concrete structures, wider cracks will occur, and when subjected to compressive forces together with concrete, they tend to buckle easily. Therefore, this study conducted tests to investigate the compressive behavior of GFRP bars and the effects when used to reinforce compressive stress in short concrete columns. The results revealed that the compressive strength of GFRP bars is 0.65-0.70 times lower than their tensile strength. Moreover, GFRP bars with a compression length greater than six times their diameter experience reduced compressive strength due to buckling. When GFRP bars are used in short concrete columns, the buckled bars push the concrete cover outward, causing it to spall off. Hence, predicting the compressive strength of short columns reinforced with GFRP bars must take buckling into account.