Question

What is the overall length of fillet weld to be provided for lap joint to transmit a factored load of 100kN? Assume site welds and width and thickness of plate as 75mm and 8mm respectively, Fe410 steel.

(a) 500mm

(b) 382mm

(c) 201mm

(d) 468mm

The question was posed to me during an interview.

My enquiry is from Design of Welds in section Welded Connections of Design of Steel Structures

Answer 1

Correct answer is (c) 201mm

For explanation I would say: Minimum size of weld = 3mm

Maximum size of weld = 8-1.5 = 6.5mm

Assume size of weld = 5mm

Effective throat thickness = 0.7 x 5 = 3.5mm

Strength of weld = 3.5×410/(√3 x1.5) = 552.33 N/mm

Required length of weld = 100 x 10^3/552.33 = 181.05 mm

length to be provided on each side = 181/2 = 90.5mm

End return = 2×5 = 10mm

Overall length = 2 x (90.5 + 2 x 5) = 201mm.