Question

An unequal angle ISA 80 mm x 50 mm x 8 mm is welded to 12 mm thick gusset plate at site as shown in figure. The angle to transmit a factored load of 120 kN. The length of weld
$l_{1}and$ $l_2$ required are respectively.

• A. 70 mm, 105 mm
• B. 45 mm, 65 mm
• C. 68 mm, 114 mm
• D. 60 mm, 90 mm

Answer 1

The correct option is C 68 mm, 114 mm

The force to be resisted by lower side of angle

$P_2=\frac{P\times \left(50\right)}{80}=\frac{5}{8}\times 120=75kN$

$\therefore$ Force to be resisted by upper side of angle
$P_1=120-75=45kN$

Strength of weld per mm length
$=t_t\times \frac{f_u}{\sqrt{3}{\gamma }_{mw}}$
$=(0.7\times 6)\times \frac{410}{\sqrt{3}\times 1.5}$
$=662.8N/mm$

$\therefore l_1=\frac{45\times {10}^3}{662.8}mm=67.9\approx 68mm$

$l_2=\frac{75\times {10}^3}{662.8}mm=113.2\approx 114mm$