Rebar, also known as ribbed steel, is a reinforced steel with ribs on its surface, typically featuring two longitudinal ribs and uniformly distributed transverse ribs along its length. The transverse ribs come in three shapes: spiral, V-shaped, and crescent-shaped. They are denoted by the millimeter number of the nominal diameter. The nominal diameter of ribbed steel is equivalent to that of a smooth round steel with the same cross-sectional area. The nominal diameter of rebar ranges from 8 to 50 millimeters, with recommended diameters being 8, 12, 16, 20, 25, 32, and 40 millimeters. Ribbed steel primarily withstands tensile stresses in concrete. Due to the ribs, it has a high bonding capacity with concrete, allowing it to better withstand external forces. It is widely used in various building structures, especially in large, heavy, light-gauge, and high-rise structures.