Page 95 - Handbook of Civil Engineering Calculations, Second Edition

1.78 STRUCTURAL STEEL ENGINEERING AND DESIGN

From the Specification, the allowable stresses are as follows: Tensile stress in connect-
ed member, 22,000 lb/sq.in. (151,690.0 kPa); shearing stress in rivet, 15,000 lb/sq.in.
(103,425.0 kPa); bearing stress on projected area of rivet, 48,500 lb/sq.in. (334,408.0
kPa); stress on throat of fillet weld, 13,600 lb/sq.in. (93,772.0 kPa).
Let n denote the number of sixteenths included in the size of a fillet weld. For exam-
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ple, for a /8-in. (9.53-mm) weld, n 6. Then weld size n/16. And throat area per linear
inch of weld 0.707n/16 0.0442n sq.in.. Also, capacity of weld 13,600(0.0442n)
600n lb/lin in (108.0n N/mm).
As shown in Fig. 54, a rivet is said to be in single shear if the opposing forces tend to
shear the shank along one plane and in double shear if they tend to shear it along two
planes. The symbols R ss , R ds , and R b are used here to designate the shearing capacity of a
rivet in single shear, the shearing capacity of a rivet in double shear, and the bearing ca-
pacity of a rivet, respectively, expressed in pounds (newtons).

CAPACITY OF A RIVET

Determine the values of R ss , R ds , and R b for a /4-in. (19.05-mm) and /8-in. (22.23-mm)
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rivet.
Calculation Procedure:
1. Compute the cross-sectional area of the rivet
2
2
For the /4-in. (19.05-mm) rivet, area A 0.785(0.75) 0.4418 sq.in. (2.8505 cm ).
3
2
2
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Likewise, for the /8-in. (22.23-mm) rivet, A 0.785(0.875) 0.6013 sq.in. (3.8796 cm ).
2. Compute the single and double shearing capacity of the rivet
Let t denote the thickness, in inches (millimeters) of the connected member, as shown in
Fig. 54. Multiply the stressed area by the allowable stress to determine the shearing ca-
pacity of the rivet. Thus, for the 34-in. (19.05-mm) rivet, R ss , 0.4418(15,000) 6630
lb (29,490.2 N); R ds 2(0.4418)(15,000) 13,250 lb (58,936.0 N). Note that the factor
of 2 is used for a rivet in double shear.
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Likewise, for the /8-in. (22.23-mm) rivet, R ss , 0.6013(15,000) 9020 lb (40,121.0
N); R ds 2(0.6013)(15,000) 18,040 lb (80,242.0 N).
3. Compute the rivet bearing capacity
The effective bearing area of a rivet of diameter d in. (mm) dt. Thus, for the /4-in.
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(19.05-mm) rivet, R b 0.75t(48,500) 36,380t lb (161,709t N). For the /8-in. (22.23-
mm) rivet, R b 0.875t(48,500) 42,440t lb (188,733t N). By substituting the value of t
in either relation, the numerical value of the bearing capacity could be obtained.

FIGURE 54