OPTIMIZATION OF RCC COLUMN SUBJECTED TO AXIAL LOAD AND UNIAXIAL MOMENT by Ansh Khurana
Abstract
In the modern development of structures, economy plays a vital role in the industry. So, for the maximum profit for builders and clients, an economical structure that is safe, serviceable and durable, is needed. Now, the cost of the structure can be minimized without deflating the material can only be done by finding a case for each of the structural members/components gives the minimum cost keeping the strength and other parameters satisfied. Columns are important vertical structural elements constructed integrally with framing beams and slabs to carry axial forces and bending moments. For optimization, number of techniques are being used by the researchers. Every technique has its own advantages and disadvantages. In the present work one of the latest developed techniques, namely ‘Ray optimization’ has been used for optimization of RC columns. This technique is based on phenomena of refraction of light. Since the technique is based on a physical phenomenon, it is easy to understand and use. Convergence of the process though depends on certain factors like the size of search space, refractive index, number of local minima etc. In this research, RC columns subjected to axial loading and uniaxial moment have been optimized. The column design depends on many factors as indicated in the interaction diagrams like eccentricity of loading, size of the column cross section, percentage of steel, position of neutral axis, grade of steel, and grade of concrete. Thus, a MATLAB program has been developed for column design with analytical formulae that doesn’t involve use of graphs. Also, a program of Ray optimization algorithm has been written in MATLAB editor and saved as functions. After writing both the programs, they have been associated with each other to work as an optimization tool for column design. Two variables namely depth of neutral axis and percentage of steel in column are considered as independent variables of the optimization problem. Variables like grade of concrete, grade of steel, length and loading are taken as inputs. The algorithm has been tested on certain standard mathematical functions to confirm its veracity and the results obtained thereby were found in concurrence with the standard results. Number of columns for different loadings were designed to validate the effectiveness of ray optimization technique. To check the robustness of the algorithm the optimization process was run multiple times. From the study it could be observed that the most optimum sections are with the cross-sectional dimensions having minimum width and minimum percentage of steel i.e. 0.8%. The study was also carried out to see the effect of different parameters like grade of steel, grade of concrete, number of design agents, variation in refractive index values etc on the optimum results. The observations of which came out to be that with the increase of grade of concrete or steel reduces the column section and thus gives more economical designs. With increasing the no. of agents, the optimum results can be obtained in less no. of iterations and for refractive index 0.5-0.8, the results are most optimum.
