Experimental Research On Eccentrically Loaded R. C. Columns With Hrbf500 Steel Bars

The standard value of 500MPa hot rolled fine grain bar's tensile strength is 500MPa. It's a new type steel bar which has many merits, such as hi-strength and strong ductility. Now this kind of steel bar has been taken in by《Steel for the reinforcement of concrete- Part 2: Hot rolled ribbed bars》(GB1499.2-2007), but it hasn't been taken in by《Code for design of concrete structures》(GB50010—2002) because the relevant testing information is absent. The study can provide theoretic and testing bases for the application of 500MPa hot rolled bars of fine grain.By the experiment on nine eccentrically loaded columns with 500MPa hot rolled bars of fine grain and one eccentrically loaded column with HRB400 steel bars, some good conclusions have been gained in this paper.The experimental research proved that the failure mode of eccentrically loaded columns with 500MPa hot rolled bars of fine grain can be divided into two species: failure of concrete be squished; failure of reinforced steel bar be pull over its yield point, comparing to the concrete column with the same spec, failure modes, deformation and fracture characteristics are identical. When 500MPa hot rolled bars of fine grain and HRB400 steel bars are taken as longitudinal main bar in the member with compression, The 500MPa bar's strength can be used sufficiently, It's bearing capacity of flexural member can be calculated by the formula of cross—section in《Code for design of concrete structures》(GB50010-2002).In this paper, analysis of the failure modes, the load-strain of the steel bar, the load-compression strain curves of concrete and the bearing capacity of eccentrically loaded columns with 500MPa hot rolled bars of fine grain are carried out, considering the eccentricity, the ratio of reinforcement, the concretes intensity, the steel bar intensity, size effect factors and so on. The results show that 500MPa hot rolled bars of fine grain works harmonically in columns, it's strength can be used sufficiently.According to the basic theoretic of reinforced concrete, analysis of the mechanics of eccentrically loaded columns with 500MPa hot rolled bars of fine grain are carried out. the design value of 500MPa hot rolled bars of fine grain in column and the formula of calculating the ultimate strength are proposed. The results show good agreement which can be used as reference to the 500MPa steel bars be used in practical engineering and be taken in by code for design of concrete structures when further modified the code.