Page 89 - Handbook of Structural Steel Connection Design and Details

Design of Connections for Axial, Moment, and Shear Forces

74 Chapter Two

It should be remembered that these are just estimates of the distor-
tional forces. The actual distortional forces will be dependent also upon
the strength of the connection. But it can be seen that these estimated
distortional forces are not insignificant. Compare, for instance, H to H .
D C
H is 218 kips tension when H is 110 kips compression. The net axial
C D
design force would then be 218 110 108 kips rather than 218 kips.
The strength of the connection can be determined by considering the
strength of each interface, including the effects of the distortional forces.
The following interface forces can be determined from Figs. 2.3 and 2.12.
For the gusset-to-beam interface:
T (tangential force) H H
B B D
N (normal force) V V
B B D
For the gusset-to-column interface:
T V V
C C D
N H H
C C D
For the beam-to-column interface:

T |V V | R
BC B D
N |H H | A
BC C D
The only departure from a simple equilibrium solution to the bracing
connection design problem was in the assumption that frame action
would allow the beam-to-column connection to be designed for an axial
force equal to the maximum of H and A, or max (218, 150) 218 kips.
c
Thus, the design shown in Fig. 2.8 has its beam-to-column connection
designed for N 218 kips and T 170 kips. Hence
BC BC
N BC 5 |218 2 H | 1 150 5 218
D
means that H 150 kips and
D
12.25
V 3 150 5 122.5 kips
D 15
From

T 122.5| 170 170
BC |V B
V 122.5 kips
B
Note that in order to maintain the beam to column loads of 170 kips shear
and 218 kips tension, the gusset-to-beam-shear V must increase from 0
B
to 122.5 kips. Figure 2.13 shows the transition from the original load dis-
tribution to the final distribution as given in Fig. 2.13d. Note also that N
BC

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