Progressive Collapse of Multi-Story Cold-Formed Steel Structures, CMS proposal 0541717
PI: LaBoube, University of Missouri-Rolla
The typical cold-formed steel wall system is composed of several key structural components: wall stud, track, bracing (for example, straps, channels, blocking, shear diaphragm, or x-bracing), sheathing material, and fasteners (typically self-drilling screws or welds). If openings are present in the wall, then additional components will be present: header beam, jack stud and king stud. Although there are two progressive collapse mitigation design approaches, the Direct Design or Indirect Design approach. The Direct Design approach will be the focus of this proposed study. Direct Design may be accomplished by either designing for a specific threat or by the Alternate Load Path Method. The focus of this proposed research will be to establish an alternate load path when perimeter columns (wall studs) are removed as the result of a catastrophic load event.
Intellectual Merit: The proposed study will provide an understanding of the behavior of a cold-formed steel structural assembly that consists of wall studs, floor joists, floor slabs, bracing members and their structural synergy related to load carrying performance to resist progressive collapse resulting from a catastrophic load event. To gain a fundamental understanding of the behavior of a framing assembly and to prepare for a more detailed overall study this initial study will focus on progressive collapse assessment of the industry standard in-line framing concept. This will be accomplished using computer simulation. This preliminary study will include an analysis capable of tracing the behavior of framed structures through collapse. Of particular interest is the capability to remove selectively various components (to simulate their localized failure) and determine if collapse will result.
Broader Impact: The Broader Impacts of the project are: advancing the state-of-the-art for design and retrofit to prevent progressive collapse of cold-formed steel structures. Culmination of the study will be the development of a more comprehensive research proposal to include small-scale and full-scale blast tests as well as some dynamic investigation to verify the structural performance against progressive collapse. Findings from this proposed work will be shared with graduate students in the UMR cold-formed steel design course and with practitioners through Dr. LaBoube's participation in the design standards development activities sponsored by the American Iron and Steel Institute.
