professor ben schafer's thin-walled structures research group - johns hopkins university

 

Direct Strength Prediction of
Cold-Formed Steel Beam-Columns

 

Note: The research reported on this page is part of the American Iron and Steel Institute sponsored project: Direct Strength Prediction of Cold-Formed Steel Beam Columns. The project also received supplementary support and funding from the Metal Building Manufacturers Association. Project updates are available at www.ce.jhu.edu/bschafer/sheathedwalls. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the American Iron and Steel Institute, nor the Metal Building Manufacturers Association.This work initiated in 2011 and is anticipated to be complete in 2013.

 

Research Abstract

This proposal provides a comprehensive program of conceptual, computational, and experimental work to modernize beam-column design of cold-formed steel members and bring this new design method immediately into the AISI Specification. The positive impacts of the proposed research are significant and worthy. For industry, the method provides a means to optimize sections for the actual loading they are expected to encounter resulting in lighter more efficient sections, tailored for their expected use. For engineers, the proposed method provides a better understanding of the relevant behavior, more transparent use of fundamental mechanics, and improved reliability. Together, these advantages allow cold-formed steel to be designed, specified, and built in a greater number of applications, with greater confidence. Beam-column design in AISI-S100 ignores the actual state of applied stress resulting from applied axial loads and bending demands and instead employs a linear interaction equation of the resultant forces and moments. Ignoring the actual applied stress distribution can result in overly conservative predictions, sometimes to a remarkably large degree. The development of the Direct Strength Method for cold-formed steel design has opened the potential for a new generation of highly optimized cold-formed steel members designed based on fundamental mechanics and checked for all relevant limit states. The adoption of Appendix 1 in AISI-S100 was a major step forward for this new approach, but currently the method only handles isolated beams and columns and provides no means for designing beam-columns. At the heart of the Direct Strength Method is the consideration of the cross-section stability under the relevant applied stress state. Extension of the Direct Strength Method to beam-columns is natural and stands to provide a significant benefit to cold-formed steel design.

 

Project Administration

Proposal and year 1 addendum (pdf)

Year 1 progress report (pdf) (all referenced reports)

Year 2 and 3 work plan and informal funding request (pdf)

Year 2 progress report (pdf)

 

Project Updates

February 2012 update for AISI (ppt) and extended update for MBMA (ppt)

July 2012 update for AISI and MBMA (pdf)

February 2013 update for AISI and MBMA (pdf)

July 2013 update for AISI and MBMA (pdf)

 

 

Project Reports

Cold-formed steel beam-column applications..., TWG-RR01-12, July 2012 (pdf)

Towards optimization of CFS beam-column industry section, TWG-RR02-12, July 2012 (pdf)

Identifying targeted CFS beam-columns for testing, TWG-RR03-12, July 2012 (pdf)

Development of DSM Direct Design Formulas for Beam-Columns, letter report, July 2012, (pdf)

Year 2 Report - Direct Strength Prediction of CFS Beam-Coulmns, Sept. 2013 (pdf)

 

last updated 07/29/12

 

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