Permissible tension in plate:

Design the size and length of weld required to develop the full strength of the smaller plate display in Figure. Thickness of the plates is 16 mm.

Solution

Permissible tension in plate = 0.6 f_y = 0.6 × 250 = 150 N/mm²

Strength of smaller plate = 80 × 16 × 150 = 192000 N

Maximum size of fillet weld = 16 - 1.5 = 14.5 mm

Throat thickness of fillet weld = 0.7 × 14.5 = 10.15 mm

Strength of weld per mm = 10.15 × 110 = 1116.5 N

∴          Total length of fillet weld = 192000/1116.5 = 172 mm

∴          Length of weld run on each side = 172/2 = 86 mm (say 90 mm)

Length of return welds = 2 × 14.5 = 29 mm (say 30 mm).