Optimization of consumed steel, opening height and location in RC beams by genetic algorithms

Abstract

In the construction of modern buildings, many pipes and ducts are necessary to accommodate essential services like water supply, sewage, etc. These pipes and ducts are usually placed underneath the concrete beams. However, for aesthetic reasons, they are covered by a suspended ceiling. Thus, to avoid increasing the height of the ceiling and dead load floor, it is more productive to pass the pipes and ducts through the beams of the ceiling. For this purpose, beams should be designed with openings. In this paper, beams with three spans and two types of uniform and non-uniform cross sections are modeled in SAP. Then beams are subjected to gravity and lateral loads and then analyzed. The results of SAP (flexural moment and shear force) are substituted in MATLAB code. Most appropriate opening positions are identified at different parts of the spans in the code and it is observed that the weight of the consumed steel in uniform beam is more than the others in greater gravity load and a large hole. Finally, steel weight is optimized once for a specified cross-section of the beam with different heights of the hole and once again for a specified height of the hole with different cross-sections of the beam by Genetic algorithm (GA). The results show that the amount of steel weight in optimal state is less than its normal value. Therefore, by decreasing the height of the hole, the width, and height of cross-section, it will be reduced to the least amount.

Keywords

• non-uniform beam
• opening
• steel weight
• optimization
• genetic algorithm