30 November 1998
Compression Members). This guidance, applied to columns built-up with cold-formed steel studs or
individual structural tubing members, is summarized in Appendix C (Paragraph C13). Columns shall be
designed such that their design strength, P (Equation C-35) exceeds the total axial applied load, Pvumax.
c. Column Bending Load and Composite Behavior. The column anchor design provisions
developed later in this guidance will create a moment connection. The primary purpose of the anchor
design is to resist shear and uplift forces. However, this anchor design will also allow the columns to act
as a moment frame, providing limited structural redundancy and widening of the hysteretic load deflection
envelopes of the shear panel. This will allow the panels to absorb more energy under cyclic seismic
loading conditions. The columns built-up from studs must be designed to act as a composite cross
section in order to provide this moment capacity. This will require welding between the studs that will
provide the shear transfer needed to develop the maximum moment in the columns. When one diagonal
strap is in tension, the full gravity load on the shear panel may be carried in a single column, with the
other column having no axial load. The maximum moment in a column will occur when it has no axial
load. Therefore the welds shall be designed for the full moment capacity of the columns. This design
requirement will allow the shear panel columns to continue providing bending resistance beyond the
lateral yield deflection of the columns. These welds shall resist the maximum shear between the studs,
which will be between the studs closest to the column neutral axis. This shear, q is defined as follows:
Vc = the maximum column shear due to column moment only.
Q = the moment of the column cross-sectional area on one side of the critical weld about the
critical weld plane.
Ic = the moment of inertia of the column due to bending in the plane of the shear panel.
The maximum column shear, Vc due to the maximum column moment Mc only is determined as
H = the panel height
Fcy = the yield strength of the column. This strength is not increased for column material
overstrength because weld failure is controlled by the column material strength, so that any
material overstrength would result in a proportionately greater weld strength.
c = the distance to the column neutral axis to the extreme fiber in the plane of the shear panel.
The moment of the column cross-sectional area on one side of the critical weld about the critical weld
plane, Q is defined as follows:
Q = ∫ ydA = Ay
A = the area of column cross-section on one side of the critical weld plane closest to the column
y = the distance from the neutral axis of the column cross-sectional area on one side of the
critical weld plane to the critical weld failure plane.