# Machine Learning Models for Ecofriendly Optimum Design of Reinforced Concrete Columns
## 1 Introduction  
Air pollution, population growth, and urban development become increasingly important with industrialization. Global warming and climate change are the most important factors affecting all human beings. The warming of the earth's atmosphere due to the release of greenhouse gases (GHGs) (CO\({}_{2}\), CH\({}_{4}\), NOx) is one of the main causes of climate change. Carbon dioxide (CO\({}_{2}\)) increases the greenhouse effect much faster than other GHGs due to its longevity. Due to inefficient CO\({}_{2}\) absorption, an imbalance in the carbon cycle is further increased [1]. Therefore, carbon dioxide emissions need to be controlled. The past eight years (2015-2022) were the warmest on record globally, fueled by ever-rising greenhouse gas concentrations and accumulated heat [2]. Extreme heatwaves, drought, and devastating flooding have affected millions of people [3]. The past nine years have been the warmest since modern recordkeeping began in 1880 [4]. People have built structures for various purposes throughout history. Concrete has been preferred as an important structural material for many years because it can be shaped easily, is resistant to physical and chemical external effects, is economical, and is practical to use and produce [5]. In addition to providing safety with engineering design, it is an advantage to have minimum cost or the least damage to the environment [6]. Reinforced concrete (RC) is a material obtained as a result of placing reinforcements in concrete. Concrete and reinforcement are used together to eliminate each other's weaknesses, provided that adherence is ensured. In this building material, reinforcement is effective in counteracting tensile effects and makes a very important contribution to the ductile behavior of the material. Concrete that is effective in supporting compressive stresses, prevents the reinforcement from buckling by wrapping it around and increases the resistance of the material against the external environment and fire resistance [7]. Table 1 shows the strengths of concrete grades between C16 and C50. However, according to TBDY 2018 [8], concrete with lower strength than C25 grade cannot be used in new buildings that will be built in Turkey. Concrete consumes more water than any other material. The concrete industry is a major consumer of freshwater [10; 11]. Concrete is formed by homogeneously mixing cement, aggregate (sand + gravel), water, and, when necessary, chemical and mineral additives in appropriate proportions [7]. The major carbon emission from the concrete industry is from the production of its main binder, which is Portland cement [10]. As shown in Table 2, China is the leading cement producer in the world. Cement production in China was approximately 2.35 billion tons in 2016. After China, India follows. Approximately 8% of the carbon dioxide emitted to the world originates from cement [12]. The cement industry, if considered a country, would be the third-largest emitter in the world after China and the US [13]. In a structure, a column carries axial loading as compression. The most ideal columns to be used in the design are circular and rectangular columns because when earthquake force acts on them, their behavior can be predicted by engineers. Rectangular columns are commonly used in the construction of buildings and heavy structures. It is easier to construct and cast this type of column. Square and rectangular columns gain less strength and ductility than circular columns because the lateral confinement for pressure distribution in the circular section is uniform, but the stress distribution of square and rectangular columns varies from maximum to minimum at the corner [15]. Figure 1 shows a general description of an RC rectangular column where the section width and height, and the lateral and longitudinal reinforcements can be seen. The section width (\(b\)), the section height (\(h\)), and the total length of the column (\(L\)) describe the geometry of the column.