560.761 Cold-Formed Steel Structures
Overview
Cold-formed steel structures see broad use in civil engineering. The primary characteristic of
such cold-formed steel structures; whether they be rack structures, buildings, or secondary
systems in larger buildings, is that due to the use of thin sheet steel, stability must be addressed
with great care. This course will provide the tools practicing engineers use to design these
structures, including codes and specifications, software tools, and experimental methods. In
addition, the course will go far beyond the typical practicing engineering implementations and
delve into the origins of the design methods in current use, the theories which underpin modern
analytical and computational tools used in exploring cold-formed steel behavior, and provide a
thorough introduction to the research currently underway in cold-formed steel structures.
Course organization
Part 1: Primarily focused on design, some homework, followed by a take home exam
Part 2: Focus on origins of design methods, underlying mechanics and theory, current research
topics, etc. some homework and/or mini-projects, followed by a final project.
A word about background
The course is open to all comers, completion of an undergraduate steel design course is nearly
mandatory. Courses in advanced (matrix) analysis of structures, advanced steel design, structural
stability, finite elements will all be helpful – but are not required. The instructor is aware that the
student’s enrolled in the course have a wide variety of backgrounds – this may mean that some
explanations offered in class will not be targeted to all students; however, sufficient material will
be provided in the course that student’s will be able to readily complete homework, succeed on
the mid-term, and complete a useful project. Specifically, expectations for undergraduate and
graduate students in this course are different.
Other Details
Course website: www.ce.jhu.edu/cfs
Instructor: Ben Schafer, schafer@jhu.edu, 203 Latrobe Hall
Office Hours: Open door policy, or by appointment
560.761 Cold-Formed Steel Structures
Topics list
Introduction to CFS
Sections, Applications, Materials, Specifications, History, Industry,
Related Organizations, Current research
Introduction to stability of CFS members (practical introduction to CUFSM)
Pcr, Mcr, local, distortional, global buckling, half-wavelength
Practical CFS Member Design by AISI-S100-07 Main Specification – Effective Width
Column
Local buckling and effective width
Local-global interaction
Distortional buckling
Beam (same breakdown)
Practical CFS Member Design by AISI-S100-07 Appendix 1 – Direct Strength Method
Column
Beam
Practical CFS Member Design by AISI-S100-07 Main Specification, complete
General, Elements, Members, Assemblies, Connections, Fatigue, DSM, 2 nd Order
(we will be on this one for a little while, as we breakdown the spec. in its entirety)
(including identification of topics for further examination as desired)
Stability of cold-formed steel members background and analytical methods
plate stability – thin plate theory
plate assemblages
member stability – flexural-torsional buckling
Effective Width
Origins
Extensions to webs, unstiffened elements, unified method
Complications with optimized sections
Computational stability of cold-formed steel members background
semi-analytical finite strip method (CUFSM)
plate  shell elements for FE implementations
comparing semi-analytical FSM results to FE sheel results
Distortional buckling
Origins
Development of design provisions
Role of restraining systems
Recent debates
Direct Strength Method
Origins
Current Work
Complications
Future Work
International cold-formed steel specifications
Eurocode (additional checks they have, other methods they use..)
Australia (Lite Steel beam provisions, earlier DB provisions)
Others? Brazilian? Hong Kong - China? India?
CFS Rack Structures
Members
Connection systems
Frame stability
Earthquake engineering of
CFS Framing
Basic framing system: walls, floors, roofs
Lateral load bearing systems
AISI-COFS Standards
Sheathed wall systems
Metal buildings and the role of CFS
Purlins, Girts, Sheeting
Standing Seam roofs
Diaphragms
Bracing cold-formed steel so that it works
Basic understanding of bracing (flexural bracing, torsional bracing…)
Cold-formed steel systems and bracing (discrete, ‘continuous’)
Where do we go from here
Imperfections and their role in CFS member stability and strength
Global imperfections, measured, impact,
Local imperfections
Distortional imperfections
General imperfection fields
Experiments with cold-formed steel
standardized testing
tension test for sheet steels
stub column tests
rotational restraint tests
fastener tests
beam tests
wall testing
Nonlinear FE modeling of cold-formed steel to collapse
inputs (imperfections, residual stress-strain, material)
element
solution controls
reliability
needs - limitations
Optimization of cold-formed steel members
parametric optimization
general shape optimization (classifiers?)
general topologic optimization
Advanced Computational Stability of cold-formed steel members
FSM for other boundary conditions
GBT
cFSM
Residual stresses in cold-formed steel members
mechanical origins
predictive model for stress-strain
connections to cold work of forming in the Spec
recommendations
Inelastic bending of cold-formed steel members
inelastic reserve in general
inelastic local, distortional, and LTB…