Page 150 - Handbook of Structural Steel Connection Design and Details

Design of Connections for Axial, Moment, and Shear Forces

Design of Connections for Axial, Moment, and Shear Forces 135

In the above weld size calculations, the worst case of gravity loads and
lateral loads is used. If it is known that one or the other only exists, only
that cases need be considered. When it is not known whether the loads
are gravity or lateral, the worst case presumed here must be used.
Note also, that is the weld size calculations, the AISC Specification
Section J2.4, which allows for increased strength of obliquely loaded fillet
welds, is not used. The compatibility requirements associated with
obliquely loaded fillets of different sizes in the same group are complex
and are not considered here.

Stresses in stiffeners (plate A). The weak axis beams are G50 steel and
are butt welded to plates A. Therefore, plates A should also be G50 steel.
Previous calculations involving this plate assumed it was A36, but
changing to G50 will not change the final results in this case because
the stiffener contact force is limited by the beam no. 1 delivered force
rather than the stiffener strength.
The stiffener stresses for the flange welds are, from Fig. 2.36 (worst case),

93
f 5 5 19.8 ksi , 1.0 3 0.6 3 50 5 30 ksi, ok
v
0.75 3 6.25
29
f 5 5 6.19 ksi , 0.9 3 50 5 45 ksi, ok
a
0.75 3 6.25
and for the web welds
29
f 5 5 3.5 ksi , 30 ksi, ok
v
0.75 3 11
107
f 5 5 13.0 ksi , 45 ksi, ok
a
0.75 3 11
2.3.2.3 Associated shear connections—beams 3 and 4. The specified
shear for these beams is R 107 kips.
Weld-to-beam web. As with the strong axis beam web connection, this
is a field-welded connection with bolts used for erection only. The design
load (required strength) is R 107 kips. The beam web shear R is
essentially constant in the area of the connection and is assumed to act
at the edge of plate A (Section a-a of Fig. 2.33b). This being the case,
there will be a small eccentricity on the C-shaped field weld. Following
AISC 13th Edition Manual Table 8-8, l 17, kl 4, k 0.24, x 0.04,
xl 0.68, al 4.25 0.68 3.57, and a 0.21. From Table 8-8 by inter-
polation, c 2.80, and the weld size required is
107
D 5 5 3.00
0.75 3 2.80 3 17
3
which indicates that a / fillet weld is required.
16

Downloaded from Digital Engineering Library @ McGraw-Hill (www.accessengineeringlibrary.com)
Copyright © 2009 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.