Simply Supported Beam Design:
1. Calculate the loads to be carried by the beam.
2. Calculate the maximum bending moment (M) with regard to the nature of loading condition and span.
3. Calculate the section modulus (Z) of the required section of the beam by the formula:
Z = M/f
where f is the safe allowable stress in steel in bending.
4. From the table “properties of beams” select a suitable section having its section modulus slightly greater than the calculated one. In making the selection of the section, deeper section should be preferred.
5. Calculate maximum shear force in the beam.
6. Check the section for safe shear stress by the formula:
s = (S/Ib) × Aȳ
s = intensity of shear stress.
S = maximum shear force in the beam.
Aȳ = The moment of the area of the part of the section situated beyond its neutral axis.
In case of a rolled steel joists, this formula may be reduced to
s = S/d×t
where d is the overall depth of the joist and t is the thickness of the web.
7. Check the selected section for its safety from consideration of allowable deflection.