Question

A steel flat plate of a rectangular section of size 70 mm x 8 mm is connected to a gusset plate by three bolts each having a shear capacity of 30 kN. If allowable tensile stress in flat is 160 MPa, the maximum tension that can be applied to flat plate is_______.

• A. $75kN$
• B. $110kN$
• C. $90kN$
• D. $85kN$

Answer 1

The correct option is A $75kN$

Net area calculation $\text{Along}1-2-3-4-6$,
$A_1=(70-3\times 10+2\times \frac{{30}^2}{4\times 20})\times 8$
$=500m{m}^2$

$\text{Along}1-2-3-5$,
$A_2=(70-2\times 10+\frac{{30}^2}{4\times 20})\times 8$
$=490m{m}^2$

$\text{Along}7-3-5$,
$A_3=(70-10)\times 8$
$=480m{m}^2$

$\therefore$ Effective net area,
$A_n=480m{m}^2$

Strength of flat in net area rupture
$=A_n\times 160N/m{m}^2$
$=480\times 160\times {10}^{-3}kN$
$=76.8kN$

Strength of bolts
$=30\times 3=90kN$
$\therefore$ Maximum load that can be applied
$=Min(76.8,90)$
$=76.8kN$