Question

One plate of size 100 mm x 12 mm is lap joined to another plate of size 200 mm x 12 mm by fillet weld of size 10 mm. Lap length is 100 mm .Fillet weld is provided on all the three sides of the smaller plate. Determine the maximum axial tension the joint could carry. Assume the plates are of mild steel of grade 250 N/$m{m}^2$.

• A. 294
• B. 155
• C. 180
• D. 196

Answer 1

The correct option is C 180

Given that:
Size of weld, S = 10 mm
Lap length, l = 100 mm
$f_y=250N/m{m}^2$

Dimension of plate 1 = 100 mm x 12 mm
Dimension of plate 2 = 200 mm x 12 mm


Strength of connection:

Total length of weld,
L = 100 + 100 + 100 = 300 mm

$\therefore$ Effective length of weld,

$l_{eff}=L-2S=300-2\times 10=280mm$

$Assumingangleofweld={90}^o$

$\therefore$ Throat thickness (t) = 0.7 x 10 = 7 mm

$\therefore \text{Strength of weld}=t\times L_{eff}\times {\sigma }_s$

where,
${\sigma }_s=0.4f_y$

$\therefore \text{Strength of weld =}7\times 280\times 0.4\times 250=196kN$

Since rupture of smaller plate will take place at lesser strength

$Tensilestrength=0.6f_y\times b\times w$

where,

$0.6f_y=permissibletensilestress$
b = breadth of plate
w = thickness of plate

$\therefore$ Tensile strength = 0.6 x 250 x 100 x 12 = 180 kN

Since it is less than strength of welded connection therefore maximum axial tension joint will carry is 180 kN.