#=64.11 kips (285.2 kN); F = 13.35 kips (59.4 kN). Let M 3 denote the moment of H
with respect to line 3. Then a = Y 2 (24 - 18.25) = 2.88 in (73.2 mm); M 3 = 633.3 in-kips
(71.6 kN-m).
With reference to Fig. 66, the tensile force Fy in the rivet is usually limited by the
bending capacity of beam flange. As shown in the AISC Manual, the standard gage in the
Wl8 x 60 is 3 Vz in (88.9 mm). Assume that the point of contraflexure in the beam flange
lies midway between the center of the rivet and the face of the web. Referring to Fig. 4Z>,
we have c = V 2 (LlS - 0.416/2) = 0.771 in (19.6 mm); Mallow =fS = 27(Y6)(3)(0.695)^2 -
0.52 in-kips (0.74 kN-m). If the compressive force C is disregarded, Fy allow = 6.52/0.771 =
8 46 kips (37 6 kN)
Try 16 rivets. The moment on the rivet group is M= 633.3 - 13.35(14.5) = 440 in-kips
(49.7 kN-m). By Eq. 3, S = 2(3)(8)(9)/6 = 72 in (1829 mm). Also, Fy = 440/72 + 13.35/16
= 6.94 < 8.46 kips (37.6 kN). This is acceptable. (The value of Fy corresponding to 14 riv-
ets is excessive.)
The rivet stresses are st = 6.94/0.6013 = 11.54 kips/in^2 (79.6 MPa); ss =
64.1 !/[16(0.6013)] = 6.67 kips/in^2 (45.9 MPa). From the Specification, shallow = 28 -
1.6(6.67) = 17.33 kips/in
2
(119.5 MPa). This is acceptable. The use of 16 rivets is there-
fore satisfactory.
- Compute the stresses in the bracket at the toe of the fillet
(line 4)
Since these stresses are seldom critical, take the length of the bracket as 24 in (609.6 mm)
and disregard the eccentricity of V. Then M= 633.3 - 64.11(1.18) = 558 in-kips (63.1
kN-m);/= 558/[(V 6 )(O^ 16)(24)
2
] + 13.35/[0.416(24)] = 15.31 kips/in
2
(105.5 MPa). This
is acceptable. Also, v = 1.5(64.11)/[0.416(24)] = 9.63 kips/in^2 (66.4 MPa) This is also ac-
ceptable.
DESIGN OFA WELDED FLEXIBLE
BEAM CONNECTION
A Wl 8 x 64 beam is to be connected to the flange of its supporting column by means of a
welded framed connection, using E60 electrodes. Design a connection to transmit a reac-
tion of 40 kips (177.9 kN). The AISC table of welded connections may be applied in se-
lecting the connection, but the design must be verified by computing the stresses.
Calculation Procedure:
- Record the pertinent properties of the beam
It is necessary to investigate both the stresses in the weld and the shearing stress in the
beam induced by the connection. The framing angles must fit between the fillets of the
beam. Record the properties: T= 153 / 8 in (390.5 mm); tw = 0.403 in (10.2 mm). - Select the most economical connection from the AISC Manual
The most economical connection is: angles 3 x 3 x^5 / 16 in (76 x 76 x 7.9 mm), 12 in (305
mm) long; weld size > Vie in (4.8 mm) for connection to beam web,^1 A, in (6.4 mm) for
connection to the supporting member.
According to the AISC table, weld A has a capacity of 40.3 kips (179.3 kN), and weld
B has a capacity of 42.8 kips (190.4 kN). The minimum web thickness required is 0.25 in
(6.4 mm). The connection is shown in Fig. Ia.