The efficiency of a riveted joint is defined as the ratio of the strength of riveted joint to the strength of the un-riveted or solid plate.

We have already discussed that

Strength of the riveted joint = Least of Pt, Ps and Pc

 Strength of the un-riveted or solid plate per pitch length,

 P = p × t × σt

 Efficiency of the riveted joint,

 η = (Least of Pt , Ps and Pc) / (p × t × σt)

 where  p = Pitch of the rivets,

t  = Thickness of the plate, and

σt = Permissible tensile stress of the plate material.