- Determine the required
number of rows of rivets
Adopt, tentatively, the minimum allowable
pitch, which is 2 in (50.8 mm) for %-in
(19.05-mm) rivets. Then establish a feasible
rivet pitch. From an earlier calculation pro-
cedure in this section, Rss = 6630 Ib
(29,490.0 N). Then T= 7425(2) = 663Ow; n
= 2.24. Use the next largest whole number of
rows, or three rows of rivets. Also, Lmax =
3(6630)/7425 = 2.68 in (68.072 mm). Use a
21 A-Ui (63.5-mm) pitch, as shown in Fig.
57a. - Determine the plate thickness
Establish the thickness t in (mm) of the steel
plates by equating the stress on the net sec- ( Q) Longitudinal pipe joint
tion to its allowable value. Since the holes
will be drilled, take^13 A 6 in (20.64 mm) as
their diameter. Then T= 22,000^2.5 - 0.81)
- 7425(2.5); t = 0.50 in (12.7 mm); use^1 X 2 -Hi
(12.7-mm) plates. Also, Rb = 36,380(0.5) >
6630 Ib (29,490.2 N). The rivet capacity is
therefore limited by shear, as assumed.
( b) Free-body diagram of upper half
MOMENT ON RIVETED of pipe and contents
CONNECTION
FIGURE 57The channel in Fig. 5Sa is connected to its
supporting column with^3 /4-in (19.05-mm)
rivets and resists the couple indicated. Com-
pute the shearing stress in each rivet.
Calculation Procedure:
- Compute the polar moment of inertia of the rivet group
The moment causes the channel (Fig. 58) to rotate about the centroid of the rivet group
and thereby exert a tangential thrust on each rivet. This thrust is directly proportional to
the radial distance to the center of the rivet.
Establish coordinate axes through the centroid of the rivet group. Compute the polar
moment of inertia of the group with respect to an axis through its centroid, taking the
cross-sectional area of a rivet as unity. Thus, J= 2(*^2 +y^2 ) = 8(2.5)^2 + 4(1.5)^2 + 4(4.5)^2 =
140 in^2 (903.3 cm^2 ). - Compute the radial distance to each rivet
Using the right-angle relationship, we see that T 1 = r 4 = (2.5^2 + 4.5^2 )^0 5 = 5.15 in (130.810
mm); r 2 = r 3 = (2.5^2 + 1.5^2 )^0 5 - 2.92 in (74.168 mm). - Compute the tangential thrust on each rivet
Use the relation / = MrIJ. Since M = 12,000(8) = 96,000 Ib-in (10,846.1 N-m),