Question 9: Steel reinforcing is used in concrete beams to prevent cracking. Explain where the steel reinforcing should be placed in a concrete beam?
Concrete is brittle (inelastic) and cannot be stretched. In other words, force (stress) may break it easily as it cannot be stretched. On the other hand, steel has a greater modulus of elasticity, i-e, it is more elastic. Therefore, when steel is used in concrete beams, the risk of cracking is reduced.
For this purpose, a steel frame of 3, 4 or 5 steel rods is prepared with the help of steel rings. The concrete structure is then developed by filling the frame and its outside with the concrete material. The steel frame thus comes inside the beam near the outer surfaces. It keeps the beam safe.
Steel rods are better to be near the surfaces of the beam.