assumptions in limit state method

following are the assumptions in limit state method

1. plane sections normal to the axis remain plane after bending.
2. maximum strain in concrete at the outermost compression fibre is taken as 0.0035 in bending.
3. the relationship between the compressive stress distribution in concrete and the stain in concrete may be assumed to be rectangular trapezoidal parabolic or of any other shape which results in the prediction of strength in substantial agreement with the results of tests.
4. the tensile strength of the concrete is ignored.
5. the stresses in the reinforcement are derived from representative stress-strain curve for the type of steel used.for design purposed, the partial safety factor is taken as 1.5 shall be applied.
6. the maximum strain in the tension reinforcement in the section at failure shall not be less than — fy/(1.15Es)+0.002
7. where fy = strength of steel , Es = modulus of elasticity of steel.