Concrete components can be reinforced and unreinforced. If the reinforcement is required, it may consist of members or mats. The reinforcement is generally used to make the component more resistant, since concrete can only absorb very limited tensile forces.
The main purpose of the longitudinal reinforcement (also called main reinforcement) is the absorption of bending tensile stresses in the longitudinal direction of the main support direction of the structural component. The cross-section of the reinforcement steel ensures that the tensile forces due to bending are absorbed with or without the longitudinal force and possibly torsion.
The longitudinal reinforcement is placed on the top and bottom sides of the plates or downstand beams. For columns, the symmetrical or radial arrangement is the rule.