Principal Tie:

A bottom tie member ADEFB is designed for a maximum tension of 54,348 N.

Permissible stress in axial tension

σ_at = 0.6 f_y = 0.6 ×250 = 150 MPa

This is increased by 33% to include wind effects

∴          σ_at allowed = 1.33 × 150 = 200 MPa

∴          Net area required = 57475/200 = 284 mm²

Select IS angle 45 × 45 × 6  (Area = 5.07 cm² @ 4 kg/m) Assuming 16 mm dia rivet holes

Area of rivet hole 17.5 × 6 = 105 mm²

Area of each leg = 507/2 = 253 mm²

A₁ = Effective area of connected leg = 253 - 105 = 148 mm²

A₂ = Gross area of outstanding leg = 253 mm²

Then, k =3A₁/(3A₁  + A₂) = 3 × 148/(3 × 148 + 253)= 0.637

Effective sectional area = A₁ + k A₂

= 148 + 0.637 × 253 = 309 mm2 > 284 mm²  ∴ OK.