Effects of Modeling Decisions on the Lateral Performance of Cold-Formed Steel Framed Walls

The main objective of this study is to propose a modeling protocol to investigate the impact of structural and non-structural detailing on the lateral performance of wall lines made of cold-formed steel (CFS) framed steel sheet shear walls. A common structural detail that impacts the lateral performance is a heavy ledger track, used to connect the floor system to the wall. This ledger track detail is often present in real buildings, but not often present in shear wall experimental testing programs. A common non-structural detail impacting the wall-line’s lateral performance is the type of finish system (e.g., gypsum board), if any. In conventional CFS wall-line design, all non-structural and many structural details are ignored, thus underestimating the strength and ductility. Additionally, wall-lines with various patterns of shear wall and gravity wall segments (not designated for lateral resistance) exist in practical building construction. A numerical study employing OpenSeesPy is validated and exercised on wall-line models with or without ledger tracks as well as with or without finishes in this study. The numerical model is also applied to an unsymmetric wall-line with different configurations to study the effects. Modeling results predict the degree by which both strength and ductility of wall-lines increase due to the presence of a ledger track and/or finish system. A sensitivity analysis is conducted to discuss the effects of various additional wall-line details including track bending stiffness, bottom track shear anchor bolt spacing, and gravity loading. The developed OpenSeesPy model can capture the impact of detailing and reveal the effects of certain wall-line configurations, thus this numerical modeling framework can be further incorporated into building-level numerical studies.

Proceedings of the Cold-Formed Steel Research Consortium Colloquium.