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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