Strain Method For Reinforcement And Deformation Of Reinforced Concrete Section

Because the reinforced concrete structure has the characteristics of sturdiness,durabilit y,and good fire resistance,it has been widel y used in construction projects.In the process of using reinforced concrete structure,it is necessar y to have corresponding regulat ions to restrain this in order to maximize the performance.The performance of steel and concrete.At present,m y country’s "Specifications for Design of Concrete Structures" has been graduall y improved,but there are still some defects compared with the content of European standards.For example: the seven stress states of the section(axial tension-small eccentric tension-large eccentric tension-pure bending-large eccentric compression-small eccentric compression-axial compression)are not considered complete,and Each section force has a corresponding calculation formula,which is more complicated to calculate.If the secti on force state jumps directl y from small eccentric compression to axial compression,the continuous change of the upper and lower edge strains of the concrete is not considered,and there is a certain The limitations;The circular cross-section reinforcement given b y t he standard formula needs to solve the transcendental equation,iterativel y,the calculation is more troublesome,and there is no non-uniform reinforcement method for the members with onl y local forces,which causes the waste of steel bars;in the calculation of cracks When the width meets the requirements of the specification,onl y the maximum crack width is calculated,and then compared with the crack width given in the specification,whether it meets the requirements,the method is simpler.The main work content of this paper is as follows:(1)The stress is calculated by strain,and the inverse solution method of internal force is calculated from the stress to calculate the excessive force state of 7 cross-sections(axial tension-small eccentric tension-large eccentric tension-pure bendinglarge eccentric compression-Small eccentric compression-axial compression),considering the situation when the section force state jumps directl y from small eccentric compression to axial compression,avoiding solving transcendental equations,and having a more thorough gras p of basic knowledge.The "Code" formula lacks the content of the non-uniform reinforcement of the circular cross-section of reinforced concrete.In the derivation of the non-uniform reinforcement formula,the difference in the position o f the center of gravit y caused b y the different distribution angles of the reinforcement is taken into account,and the dimensionless bending is obtained.The nomogram of moments and correlation coefficients can be applied to concrete strength grades of C5 0 and below.If the strength of the steel bar changes,the corresponding nomogram can be obtained onl y by changing the design value of the tensile strength of the steel bar.Reduce the complexit y of calculation.(2)The bending moment-curvature curve is ob tained through anal ysis,and the relationship between bending moment-axial force-curvature under the condition of fixed section reinforcement ratio will be intuitivel y seen,and it can be obtained by simple conversion In the case of fixed axial force,the bending moment-curvaturesection reinforcement ratio can be divided into elastic stage,elastoplastic stage and plastic stage by the curve.The bending stiffness and section ductilit y of the section can be anal yzed,and the ductilit y coefficient can be cal culated.The internal force redistribution and bending moment amplitude modulation make the engineering design more reasonable,and the ductilit y coefficient can also be used to judge the seismic performance.The bending moment-curvature curve can indicate the flexural load-bearing capacit y of the component and predict the deformation capacit y of the component.(3)The method of crack width control is converted from checking the crack width to solving the maximum steel bar diameter limit,avoiding the compl exit y of directl y calculating the crack width,drawi ng a graph between the stress of the steel bar,the reinforcement ratio and the diameter of the steel bar.The lowest point of the three correlation curves is regarded as the maximum steel bar diameter un der the limit of the crack width;by changing the thickness of the concret e cover,the standard value of concrete tensile strength and the cross-sectional height and other factors that affect the steel bar diameter,the changed curve is drawn to obtain the steel bar Uniform diameter adjustment formula.When the size of the base is changed,the adjusted maximum steel bar diameter limit can be obtained through the adjustment formula.