TO IMPROVE CALCULATION OF DEFLECTION FOR CONCRETE STRUCTURAL MEMBER BY FINITE INTEGRAL METHOD

The calculation of deflection for concrete structural member that was put forward in Code for Design of Concrete Structures was an approximate method.Similar methods were also put forward in some foreign codes or standards for concrete structures.The mentality for this kind of approximation calculation consisted of two steps.Firstly,curvature was calculated with bending moment.Secondly,deflection was calculated by curvature with the help of mechanics.It was unreasonable to calculate deflection by curvature with the help of mechanics.Essentially,the calculation of deflection by curvature was a geometric problem,and integral method should be used to resolve this problem.Based on the numerical equation between the deflection and its derivative or the relation between the derivatwe and the second derivative of deflection in finite integral solution,deflection-curvature matrix was derived by matrix operation,and the curvature-deflection equation was derived with functional relation (x)=-z(x).The curvature-deflection equations for some kinds of common boundary conditions were discussed.The methods and formulae of deflection calculation for concrete structural member were put forward.Calculation showed that it was convenient to improve the approximation calculation of deflection for concrete element by finite integral method.The accuracy of calculation was greatly improved.