Question

Two steel plate each 300 mm wide and 10 mm thick are connected by single bolt. If the plates are in tension and diameter of bolt hole is 20 mm, the net section area of the plate will be
1. 2686 mm²
2. 2780 mm​2
3. 2800 mm​2
4. 3000 mm​2

Answer 1

Correct Answer - Option 3 : 2800 mm​2

Concept:

Tensile strength of plates is given by

\({T_{nd}} = 0.9{A_n}\frac{{{f_u}}}{{{γ _{m1}}}}\) where,

f_u = ultimate stress of a plate

A_n = Net sectional area of plate

γ_m1 = partial safety factor for material strength governed by ultimate strength = 1.25

Net sectional area of plate is given by

\({A_n} = \left[ {B - n{d_h} + \sum\limits_{i = 1}^m {\frac{{{p^2}_i}}{{4{g_i}}}} } \right]t\)

where, p = pitch of the bolt and g = gauge of the bolt

Calculation:

Given,

Plates are in tension

Steel plates Width, B = 300 mm and thickness, t = 10 mm

Bolt hole diameter, d_h = 20 mm

Here since single bolt, p = 0 and g = 0

Net section area of plate, A_n = (B - nd_h) × t 

A_n = (300 - 1 × 20) × 10 = 2800 mm²