Rivets
• Advantages
–
–
–
–
Cheap, especially in assembly time
Don’t shake loose like bolts
Lightweight
Easy assembly
• Disadvantages
– Not as strong as bolts (end must yield to form head)
– No disassembly
Rivets
• Use as many as possible without reducing
member cross section too much.
– Minimum spacing = 3 diameters.
– Closer in boilers.
• Maximum spacing = 16 times thickness of
outside plate.
1
Failure Modes
Bending of member:
Rarely important
Shear of rivet (Most important mode)
τ=
P
4P
= 2 must be < S sy = 0.4 S y
Arivet d
Rivet diameter = d
Rivet shear strength = 0.4Sy
Text Reference: Figure 15.18, page 695
Failure modes
Tensile of member:
σ=
P
must be < S y memb
(b − N r d )tm
width
Reduction =
# of rivets x diameter
Bearing (contact) stress of member:
σ=
P
must be < 0.9 S y memb
d tm
2
Group of rivets
• Rivets are used in groups.
• Offset load can shear rivets around a centroid.
dB = dD = 7/8”
dA = dC = 5/8”
Shear stress on each rivet = ?
Do Example 15.9 !
Group of rivets
=
Direct shear:
Assume uniform
force per unit area.
P
τd =
∑A
Torsional shear:
τt =
=
Tr
J
π 4

2
J = ∑  d i + ri Ai 
i
i 2
small
3