Study On The Mechanical Behavior Of The GFRP Confined High Strength Concrete Columns Under Eccentric Load

The building structures need to be strengthened because of the deterioration as time goes by, the change of the load and the damage by the earthquake. FRP-confined concrete is superior to the traditional strengthening technique as FRP materials have the advantage of lightweight, high strength and duration, so FRP-confined concrete is a hot research area. The research of FRP reinforced concrete columns are focus on the strain stress relationship of FRP-confined concrete, the mechanical behavior of FRP-confined concrete columns under axial load, the mechanical behavior of FRP-confined concrete columns under eccentric load and the seismic behavior of FRP-confined concrete columns. Because many columns are under eccentric load, the research of FRP-confined concrete columns under eccentric load is significant. Base on the research achievement some countries issue FRP-confined concrete standards to guide strengthening engineering.This paper introduce the provisions of FRP-confined concrete columns of guide for FRP strengthening concrete structures published by ACI committee440,concrete society and Chinese design code for strengthening concrete structure, then the provisions are compared. In order to compare the strengthening method and computing method and investigate the mechanical behavior of FRP-confined concrete columns under eccentric load,10concrete specimens are tested, among them2specimens are reference specimens,8specimens are GFRP-confined columns. The variable parameters of test include eccentricity, quantity of GFRP wrapping and method of wrapping, the experimental phenomenon and failure mode of the test were analyzed, the effect of the reinforcing columns was compared, the specimens were calculated using the formula in the different standards.The result indicates that the effect of the columns with different strengthening method is different. Bonding hoop GFRP to the columns enhances the load bearing capacity and ductility of the columns, especially the small eccentric columns. Bonding axial GFRP enhances the load bearing capacity of the large eccentric columns. Bonding the hoop GFRP over the axial GFRP is the most efficient method, it can improves both the load bearing capacity and ductility of the columns. The calculated results show that the calculating method can meet the requirement of the civil engineering, it is recommended that the suitable wrapping method and the calculating method is used according to the different engineering practice.