Rivets in Several Rows:

If the number of rivets required is large and the width of the plate is not sufficient to accommodate them in one row, more than one row of rivets has to be given. The following example shows the calculation.

Example

Find the safe strength of the double covered butt joint shown in Figure, where power driven shop rivets of 20 mm nominal diameter are used. All plates are 18 mm thick, and f_y = 150 MPa.

Figure

Solution

Gross diameter of rivets = 20 + 1.5 = 21.5 mm

A maximum permissible stresses for power-driven shop rivets have been taken from Table 2.

Shearing strength of 6 rivets in double shear

= [2 × 100 × π /4× (21.5)2] × 6 = 435, 660 N

Strength of six rivets in bearing

= (18 × 21.5 × 300) × 6 = 696,600 N

Tearing strength of main plate along plane (1)-(1)

= (300 - 21.5) × 18 × 150 = 751, 950 N

Tearing strength of main plate along plane (2)-(2)

= (300 - 2 × 21.5) × 18 × 150 = 693, 900 N

But tearing along (2)-(2) can take place only when rivet at (1)-(1) also fails in shear, the value of which is

[2 × 100 (π/4) × (21.5)² ]  × 1 = 72610 N

∴ Tearing strength along (2)-(2) = 693,900 + 72,610 = 766, 510 N

Similarly, tearing along (3)-(3) along with shear failures of 3 rivets at (1)-(1) and (2)-(2)

= (300 - 3 × 21.5) × 18 × 150 + 2 × 100 × π/4 × (21.5)2 × 3

= 853, 680 N

Taking the least value of above, a safe strength of the joint is 435, 660 N

≅ 435 kN.