Question

Cracks in R.C. element in bending. Explain their role and why their width should be limited?

Answer 1

Bending cracks in RC beams can be seen on the tension side of the beam. This is because of the low tensile strength of the concrete.

Even though concrete in tension region is not considered for flexural capacity, it plays major role in durability and serviceability aspects.

Increase in crack width decreases the stiffness and increases the long term deflection in the beam by further increasing the crack propagation and decreasing the serviceability of the beam.

Further increase in crack width allows penetration of harmful chemicals into the beam which can affect the reinforcement and hence overall strength also. Thus it reduces the durability of the beam.

Therefore, crack width should be limited to avoid serviceability (deflection and cracks) and durability problems.