Of the following four sections, which section has the maximum Pla

SOLUTION

Plastic sectional modulus, \({{\rm{Z}}_{\rm{p}}} = \frac{{\rm{A}}}{2}\left( {\overline {{{\rm{y}}_1}} + \overline {{{\rm{y}}_2}} } \right)\)

Where,

A = cross-sectional area,

y̅₁ and y̅₂ = centroid of areas measured from plastic neutral axis.

It is clear from above that, Z_D ∝ A

Now IS code (SP 6-1), the higher the weight of member higher will be its cross-section area.

∴ ISHB250 has maximum area among the all given options so, it has maximum plastic modulus.

Important point:

ISMB250 - Indian Standard Medium Weight Beam having overall depth 250 mm.

ISHB250 - Indian Standard Heavy Weight Beam having overall depth 250 mm.

ISWB250 - Indian Standard Wide flanged Beam having overall depth 250 mm.

ISLB 250- Indian Standard Light Weight Beam having overall depth 250 mm.