Experiment Of Reinforced Concrete Columns With GFRP Bars Under Eccentric Axial Compression Load And Longitudinal Reinforcement Calculation

Fiber Reinforced Bars in harsh environments such as Marine,saline and chlorine ion showed excellent corrosion resistance.Reinforced concrete with FRP Bars has become the one of the most effective solution for steel bars corrosion,which,can fundamentally solve structure safety problem,as a result of environmental erosion.At present,there are a lot of research of the cross section of reinforcement design about FRP reinforced concrete flexural members with some guidelines,but less of FRP reinforced concrete compression members,furthermore,the minimum and maximum FRP reinforcement ratio has not yet provided a clear calculation method.Column is generally subjected to eccentric axial load.In this paper,an experiment of reinforced concrete columns with FRP bars under eccentric axial load is carried on,then,have a research of the cross section design about FRP longitudinal.And,this paper put forward to a calculation of boundary of eccentric type about FRP reinforced concrete columns,then,derive a equation about FRP longitudinal design.Finally,this paper has a detailed research of minimum and maximum reinforcement ratio of FRP longitudinal.This article mainly carried on several aspects of work:First,the experiment of 7 reinforced concrete columns with GFRP bars under eccentric axial compression load.In this experiment,failure characteristics,ultimate and deformation capacity are studied,considering the longitudinal reinforcement ratio and eccentricity.Test results indicate that,GFRP reinforced concrete columns have two main failure mode: 1)concrete crushing;2)tensile failure of GFRP bars;The longitudinal reinforcement ratio is the main factor of the failure characteristics;In the case of the first failure mode,the ultimate capacity is proportional to the reinforcement ratio of the longitudinal bar and inversely proportional to the eccentricity.The deformation ability decreases with the increase of the reinforcement ratio.Second,according to the test results and steel reinforced concrete column under eccentric axial load,GFRP reinforced concrete column can be divided into part of section compression and total section compression,when column reaches expected failure mode,namely concrete crushing.Then,according to the FRP reinforcement loading characteristics,putting forward to the calculation method of section reinforcement design.Third,the design results of reinforcement ratio will not be able to meet the demand of engineering.Similarly to the prevention of less or more reinforcement damage,it is much significant and critical to define "proper reinforcement" scope of FRP reinforced concrete member,three detailed studies has been carried: 1)putting forward to a more practical equation of FRP minimum reinforcement ratio about FRP flexural members and FRP reinforced concrete columns,on the base of the minimum reinforcement ratio of FRP reinforced concrete flexural members in code.2)According to the Deformation Factor(DF)method,the calculation of the maximum reinforcement ratio of FRP reinforced concrete flexural members is presented.3)The equation of maximum reinforcement ratio of FRP reinforced concrete column considering concrete creep,shrinkage and unloading rule under earthquake is proposed.