Page 169 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch03.qxd 9/29/05 5:05 PM Page 3.101

CONNECTIONS

CONNECTIONS 3.101

FIGURE 3.56 Nonconcentric uniform force method. (Source: A. R. Tamboli,
Handbook of Structural Steel Connection Design and Details, McGraw-Hill, 1999,
with permission.)

and must satisfy the constraint shown in the box in Fig. 3.55. This can always be arranged when
designing a connection, but in checking a given connection designed by some other method, the
constraint may not be satisfied. The result is gusset-edge couples that must be considered in the design.
In Fig. 3.55, the angle, γ, is positive as shown. If the angle between the column and the beam is greater
than 90°, γ is negative.

Connections with Nonconcentric Workpoints. The uniform force method can be easily general-
ized to this case as shown in Fig. 3.56, where x and y locate the specified nonconcentric workpoint
(WP) from the intersection of the beam and column flanges. All of the forces on the connection inter-
faces are the same as for the concentric uniform force method, except that there is an extra moment
on the gusset plate M = Pe, which can be applied to the stiffer gusset edge. It should be noted that
this nonconcentric force distribution is consistent with the findings of Richard (1986), who found
very little effect on the force distribution in the connection when the work point is moved from con-
centric to nonconcentric locations. It should also be noted that a nonconcentric work-point location
induces a moment in the structure of M = Pe, and this may need to be considered in the design of the
frame members. In the case of Fig. 3.56, since the moment M = Pe is assumed to act on the gusset-
to-beam interface, it also must be assumed to act on the beam outside of the connection, as shown.
In the case of a connection to a column web, this will be the actual distribution (Gross, 1990), unless
the connection to the column mobilizes the flanges by means of stiffeners.

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