Steel Structures

Read I, Z and r for the rolled section from SP 6(1) tables, and remember that limit-state steel design uses the plastic modulus Z_p (not the elastic Z) for moment capacity.

Compute both the gross-section yield strength and the net-section rupture strength (deducting bolt holes), and take the design capacity as the smaller of the two.

Find the slenderness ratio about the weak axis, pick the buckling class for the section, read the design compressive stress f_cd from the IS 800 curves, and multiply by area for the capacity P_d.

Classify the section, compute the plastic moment capacity M_d = β_b Z_p f_y/γ_m0 for a laterally supported beam (reduce it for lateral-torsional buckling if unsupported), and separately check shear and deflection.

For bolts compute the least of shear and bearing strength per bolt and divide the load to get the number required; for fillet welds use the throat thickness 0.707a and the weld design strength to find the length.