Research On Crack Width Of Concrete Beam Reinforced With 600MPa Steel Bars

Whether the 600 MPa high strength reinforced concrete beam crack width meets the requirements of the codes was widely concerned.In this paper,the experimental study and theoretical analysis of the crack of 600 MPa high strength reinforced concrete beam were carried out,which provides data support for the popularization and application of 600 MPa high strength reinforcement.There were fourteen 600 MPa and 400 MPa reinforced concrete beams designed and tested for bending performance while considering the parameters such as reinforcement ratio,concrete strength and reinforcement strength.The crack propagation process,crack morphology,average crack spacing and the distribution law of crack width were analyzed.The results showed that the crack propagation process of 600 MPa reinforced concrete curved beam was similar to the ordinary reinforced concrete beam.Concrete strength has no significant effect on the average crack spacing.With the increase of the reinforcement ratio,the average crack spacing and the crack width were reduced.The strength of the steel bar has no obvious effect on the average crack spacing.With the increase of the reinforcement strength,the crack width added.The average spacing and crack width of fractures can be reduced by adding steel fiber to 600 MPa high strength reinforced concrete beam.Under the same conditions,the short term maximum crack width calculated according to GB 50010-2010 formula was greater than by Frosch formula(ACI 318-14 used)and the EN 1992-1-1:2004 formula calculated,and the calculated result was sensitive when the steel stress changed.The code GB50010-2010 provision of the crack width of the allowable value was more stringent than the European and American codes.Based on the comprehensive calculation model of the code GB50010-2010 crack formula,considering the combined effect of concrete cover and reinforced concrete bonding slip,according to the relevant experiments and this test data,the average spacing of cracks were modified by this bending beam test data.The calculated value of the modified formula was in good conformity with the experimental value.The short term maximum crack width was adjusted by the average crack spacing correction formula.The influence coefficient of steel fiber on the crack width of steel fiber reinforced concretebeams was obtained by fitting the experimental data.