The paper firstly expounds the design principles and fundamental assumptions of flexural and compressive reinforced concrete members in Building Code Requirements for Structural Concrete（ACI318-08）.Different from Chinese design code of concrete structures

ACI318-08 determines the reduction factor of nominal compressive and bending capacity according to the member′s stress failure mode.The degree of a member′s capacity reduction in the brittle failures is greater than that in the ductile ones.Then a calculation formula of Tsung-wu LIN linear method is proposed on the basis of the equilibrium condition

plane section assumption

and Newton′s iterative method.In computer implementation of the algorithm for the formula

limitation of iterative region according to the maximal and minimal reinforcement ratio is necessary;in addition

the location of inflection points in P-M Relative Curves should be determined in order to realize the respective iteration of the neutral axis height in the curve.Through the establishment of small increment in curve′s inflection points as well as the automatic adjustment of the neutral axis height

the possible iterative divergence problem of Tsung-wu LIN linear method in computer programming is solved.The results show that numerical solutions from the computer program are of high precision.