Parametric Study of Hole Pattern Influence on Average Bending Stiffness

The presence of holes in cold-formed steel structural members reduces the global buckling capacity. Current design provisions in the North American Specification for the design of coldformed steel members utilize a simple reduction in member stiffness caused by holes. The crosssection moment of inertia is a weighted average of the gross and net section values, but this is restricted to cases where the hole locations are symmetric about the midpoint of the member. For other hole patterns, the Commentary provides a more precise calculation using an exhaustive summation over the member length considering each hole location. In practice, it is common to have uniformly spaced holes, but not necessarily centered across the member. The purpose of this investigation is to assess the impact of offset and other hole patterns, and determine if the simple weighted average method can be extended for broader application.

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