Reason for Cracking in Reinforced Concrete Members

Cracking in reinforced concrete members is attributable to various causes, particularly:

  • flexural tensile stress due to bending under applied loads;
  • diagonal tension due to shear and torsion;
  • direct tensile stress under applied loads (for example, hoop tension in a circular water tank);
  • lateral tensile strains accompanying high compressive stress/strain due to the Poisson effect (as in a compression test) or due to heavy concentrated loads as in a split cylinder test;
  • restraint against volume changes due to shrinkage and temperature, as well as due to creep and chemical effects; and
  • additional curvatures due to continuity effects, settlement of supports, etc.

Factors Influencing Crack-widths

  • tensile stress in the steel bars;
  • the thickness of the concrete cover;
  • diameter and spacing of bars;
  • depth of member and location of neutral axis; and
  • bond strength and tensile strength of concrete.

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