Integrated Interaction Diagrams for Sections Subjected to Axial Force and Bending Moment According to the American Concrete Institute and the Saudi Building Code

Abstract

The Saudi Building Code for the design of concrete structures (SBC304) is identical to the American Concrete Institute metric code (ACI318M-19); therefore, any design aids developed for one of them could be used for the other. When designing a reinforced concrete section that is subjected to an axial force accompanied by a bending moment, an interaction diagram is needed. Most textbooks provide interaction diagrams based on imperial units and only a few provide these interaction diagrams based on metric units. Moreover, the new proposed interaction diagrams have advantages compared with the available diagrams in the textbooks. They do not only consider axial compression forces but also tension forces. The portion above the maximum allowable axial compression force is not displayed in these diagrams to prevent users from using this part of the diagrams since according to the code requirements, which is not permissible. In addition, these diagrams allow one to use ratios of compression to tension reinforcement different than 1.0, which is the only ratio available in the textbooks. A wide range of ratios for the lever arm of extreme reinforcement to the section depth is presented in the diagrams with a 0.05 step. Also, numerous values of concrete strength (f ^\_c ) ranges are covered. Finally, along with the nominal interaction diagram plots, ultimate (design) interaction diagrams are created as well, which provide easier usage. To verify the accuracy of these interaction diagrams, several examples from many textbooks were resolved using these diagrams and the results were shown to be compatible.