The Experimental Research On Reinforced Concrete Column By Hrbf500 Bars

Now this kind of steel bar has been taken in by《Hot ribbed bar of reinforced conrete》(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 fine- grained bars.By experiment of eight axially loaded columns with 500MPa steel bars and one with 400MPa bars, nine eccentrically loaded columns with 500MPa steel bars and one with 400MPa bars, they were observed that the development of the crack and failure mode. The experimental research proved that the failure mode of eccentrically loaded columns with 500MPa hot rolled bars of fine grain 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 compressionAccording to the basic theoretic of reinforced concrete, analysis of the mechanics of axially loaded columns and 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.The maximum crack width and the average spacing of the 500MPa fine-grained bars can be calculated by the formula of cross-section in《Code for design of concrete structures》(GB50010-2002), the maximum crack width under the long-term effects is far less than the calculated values of crack width, but the calculated values of crack width is greater than specification of restrictions. In this paper, comparative analysis of the members'crack width case the bais components and the flexural members configuration of the bias 500MPa fine-grained bars. The crack width that of bending members is biger than the bias component, components by the stress state impact the crack width. To standardize the calculation of maximum crack width in the proposed amendments to the "norms" (GB50010-2002), when calculating the maximum crack width, the force coefficient characteristics of the bias componentsαcr=1.7, the force coefficient characteristics of the flexual componentsαcr=1.9,the results of the bias components and the bending components have the same component reliability, and there is enough safety reserves.