Page 153 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch03.qxd 9/29/05 5:05 PM Page 3.85

CONNECTIONS

CONNECTIONS 3.85

The uniform force method produces a load path that is consistent with the gusset plate boundaries
and eliminates moments at the connection interfaces. See Thornton (1991, 1995b). For instance, if the
gusset-to-column connection is to a column web, no horizontal force is directed perpendicular to the
column web because, unless it is stiffened, the web will not be able to sustain this force. This is clear-
ly shown in the physical test results of Gross (1990), where it was reported that bracing connections
to column webs were unable to mobilize the column weak-axis stiffness because of web flexibility.
The uniform force method is strongly tied to the geometry of the structure, as can be seen in Fig. 3.48.
The relationship of the angle of the brace, the depth of the beam, the depth of the column, and the
choice of α or β determines the force distribution at all member interfaces. To calculate the forces at

V P
θ
H

V P
b
H
W.P. H c
e b
V c
R
R c H b
Column control point
V b
R b
Beam control point W.P.
e c α Gusset control point
(a) (b)

R c
V c
H c V θ P
e c α
b R H
V b H b b
W.P. V b e W.P. V
H c b b H
H c
R
R
R–V
e c
(c)
FIGURE 3.48 The uniform force method. (a) Geometry including control points. (b) Forces acting on the gusset. (c) Forces
acting on the beam and column.

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