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Reg. 177
SHELLS


Methods of calculating the strength of riveted joints

a) The percentage of strength of a riveted joint (J) shall be found from the following formulae (i), (ii), (iii); (i) and (ii) are applicable to any ordinary type of joint, (iii) is applicable only to that type of joint in which the number of rivets in the inner rows is double that of the outer row. The lowest value given by the application of these formulae is to be taken as the percentage of strength of the joint compared with the solid plate.
(i) 100(P - D) = Plate percentage Eqn.(2).
P

(ii) 100 x A x N x C x S1
= Rivet percentage Eqn.(3)
P x T x S

(iii) 100(P - 2D)
+ 100 x A x C x S1 = Combined plate and rivet percentage . Eqn.(4)
P P x T x S

Where

P is the pitch of rivets of outer row in inches.

D is the diameter of rivet holes in inches.

A is the sectional area of one rivet hole in square inches.

N is the number of rivets per pitch (P).

T is the thickness of plate in inches.

C = 1 for rivets in single shear as in lap joints, and 1.875 for rivets in double shear as in double butt strapped joints.

S1 is the shearing strength of rivets which shall be taken to be 23 tons per square inch for steel and 18 tons per square inch for iron.

S is the minimum tensile breaking strength of shell plates in tons per square inch, or whatever strength is allowed under Regulation 5 of chapter I,

In the first formula (i) D is the diameter of the rivet holes in the outer rows and in the third formula D is the diameter of the rivet holes in the next rows. In the last formula A is the area of one rivet hole in the outer row
b) When the sectional area of the rivet holes is not the same in all rows, and when some of the rivets are in double shear and others in single shear the rivet sections per pitch of each size in shear shall be computed separately and added together to form the total rivet section.
 
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