Modeling Cold-formed Steel Framed Wall-lines with Steel Sheet Sheathed Shear Walls

The objective of this work is to present a validated modeling protocol for simulating the seismic behavior of cold-formed steel (CFS) framed wall-lines. Wall-lines in this work are defined as having one or more gravity segments placed in line with one or more steel sheet sheathed shear walls. Validation is performed against recently completed dynamic and quasi-static (cyclic) tests on CFS-framed wall-lines. The tested wall-lines include shear walls (placed symmetrically, or at one end of the wall-line), gravity walls, framed openings, varied chord stud anchorage conditions, and varied finish details. The wall-line test specimens exhibit significant overstrength when compared with standards such as American Iron and Steel Institute (AISI) S400–20, which only consider lateral strength from isolated shear walls. To investigate the seismic performance of CFS-framed buildings, a robust modeling strategy capable of reproducing the behavior of actual CFS-framed wall-lines is needed. To this end, a mixed modeling protocol, combining phenomenological-based models for wall sheathing and mechanics-based structural analysis models for wall framing and anchorage, is implemented in OpenSeesPy and validated against the selected wall-line tests. The developed model is utilized to elicit the expected distribution of internal forces and base shear in CFS-framed wall-lines under lateral demands. The developed modeling protocol verifies that the overstrength ratio of wall-line configurations with both structural and non-structural detailing can be as high as two. The validated modeling protocol is intended for studies contributing to seismic performance-based design, validating seismic response modification coefficients, conducting Tier 3 retrofit analysis per American Society of Civil Engineers (ASCE) 41, and improving seismic force resisting systems in CFS-framed buildings.

Thin-Walled Structures, 214, 113408