Formulation of P-M Interaction Diagram by Applying Uniformly Distributed Reinforcement and Determination of RC Pylon Sections for Target Reliability

Abstract

This paper suggests a method to determine the optimum cross sections of RC pylons that satisfy the target reliability level. P-M interaction diagram is formulated based on uniformly distributed reinforced concrete to generalize the strength of RC column sections. Reliability analysis is conducted by HL-RF algorithm with gradient projection method. An optimum section that satisfies the target reliability level is determined for one of transverse and longitudinal direction or both of them. Object function is selected for reliability index requirement and the equation is solved by Newton-Raphson method with reinforcement equation or regularization function. The validity of method is demonstrated for two pylon section examples, Inchoen Bridge and Ulsan Bridge. When the reinforcement equation and regularization function are used for finding optimum sections, respectively, it is verified that the results are in agreement with each other under same reinforcement ratio condition. The fea-sibility of optimum section with general rebar is checked by placing the equivalent rebar in the cross section