Page 110 - 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 95

see Sec. 2.2.1.2. Normally, the gusset is squared off as shown in Fig. 2.23,
which gives 16 rows of bolts in the gusset-to-truss vertical connection.
The gusset-to-top chord connection is pretty well constrained by geom-
1
etry to be about 70 in long plus about 13 / in for the cutout. Starting
2
from the configuration of Fig. 2.23, the UFM forces are calculated from
the formulas of Fig. 2.20 and the design is checked. It will be found that
Fig. 2.23 is a satisfactory design via the UFM, even though it fails via
the KISS method forces of Fig. 2.21. Although the gusset-to-top chord
connection cannot be reduced in length because of geometry, the gusset-
to-truss vertical is subject to no such constraint. Therefore, the number
of rows of bolts in the gusset-to-truss vertical is sequentially reduced
until failure occurs. The last-achieved successful design is the final
design as shown in Fig. 2.24.
The calculations for Fig. 2.24 and the intermediate designs and the
initial design of Fig. 2.23 are performed in the following manner. The
given data for all cases are:

P 920 kips
e 7 in
B
e 7 in
c
17.7

36.7

The relationship between and is
(0.9527 0.7454 0.3040) 7(0.7454 0.3191) 7/0.9527
0.4061 4.363
This relationship must be satisfied for these to be no couples on the
gusset edges. For the configuration of Fig. 2.24 with seven rows of bolts
in the gusset-to-truss vertical connection (which is considered the gusset-

to-beam connection of Fig. 2.20) 18.0 in. Then,
18 1 4.363
55.07 in
0.4061
From Fig. 2.24, the centroid of the gusset to top chord (which is the gusset-

to-column connection of Fig. 2.20) is 13.5 70/2 48.5 in. Since
, there will be a couple on this edge unless the gusset geometry is

adjusted to make 55.07. In this case, we will leave the gusset geom-
etry unchanged and work with the couple on gusset-to-top chord interface.

Rather than choosing 18.0 in, we could have chosen 48.5 and

solved for . In this case, a couple will be required on the gusset-to

truss vertical interface unless gusset geometry is changed to make .
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