روش طراحی مستقیم و نمودار طراحی برای ستون های بتن مسلح و دیوارهای برشی Direct Design Method and Design Diagrams for Reinforced Concrete Columns and Shear walls

INTRODUCTION The accepted approach for design of concrete columns under combined axial load and bending moments is using the Short Column Interaction Diagrams along principal axes of symmetry1 . Interaction diagrams for columns are generally computed by assuming a series of strain distributions, each corresponding to a particular point on the interaction diagram, and computing the corresponding values of P and M 2 . The design procedure starts by assuming a column cross section and checking its capacity using the corresponding interaction diagram. If the selected section capacity does not satisfy applied load and moments, a new section is assumed. The procedure continues until an appropriate section is found. The column section founded by conventional approach is not necessarily a fitted section. Finding a fitted section, which its capacity is exactly equal to applied load and moments requires more trial-and-error. In addition, for any set of applied axial load and moments, it is possible to find several fitted sections with different section sizes, bar arrangements, and bar areas. The main objective of this paper is to present a general procedure by which all fitted solutions for a column or shear wall are found and presented on a design diagram. This paper also proposes the direct design method for designing concrete columns. A system of equations is prepared based on the section shape and bar arrangement. By solving this system of equations, the required area of reinforcement bars is determined directly without using diagrams or tables. The resulting solution represents a fitted section since its capacity is equal to the applied load and moments. The provided procedure is not limited to any cross section shape or any particular stress-strain diagram for concrete and reinforcement. RESEARCH SIGNIFICANCE An efficient and straightforward method for designing reinforced concrete columns and shear walls is presented in this paper. This method creates a design diagram for a short column or shear wall based on the applied load and moments. The provided design diagram shows all possible fitted sections for the column. Design diagram is a practical tool by which design of column 3 would be much faster, easier, and efficient, since the designers have all practical fitted solutions in one diagram.