A Study on Economical Design of Reinforced Concrete Tie Columns

Abstract

Designing a reinforced concrete column to resist an axial load and bending moment is an iterative procedure which involves tedious calculations. The design is influenced by many variables, such as load eccentricity, column cross-section size, steel percentage, neutral axis location, steel grade, and concrete grade, requiring the use of interaction diagrams. In the present research, an attempt was made to determine the optimum design under direct load, uniaxial and biaxial moments of reinforced concrete columns that meets all ACI-318 code specifications and therefore results in minimum cost. The purpose of the paper is to achieve the optimum design of the columns of reinforced concrete. Column optimisation results in cost savings. The objective function is to minimize the total cost of the column. It is consists of the cost of concrete, reinforcement, formwork and links per unit length of column. Concrete and steel strength, cross-sectional dimensions, and steel bar diameters used as longitudinal reinforcement and tie were treated as design variables in the formulation of the optimal design problem. The optimal design was performed using the program MATLAB (The Mathworks, Inc.). The problem of optimization was conceived as a problem of nonlinear, restricted minimization. Many problems have been formulated and the best solutions have been obtained. It was noticed that the most economical design is provided by the solutions. The use of optimal quantities of reinforcement advances the goal of enhancing the sustainability of the construction of reinforced concrete.