Transcript The Direct Strength Method of Cold

Wrap-up
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summary
carrot
stick
crystal ball
• Familiar with the terms Local (Mcrl), distortional (Mcrd)
and global (Mcre) elastic buckling
• Able to perform elastic buckling calculations using the
finite strip method (CUFSM)
• Able to use the Direct Strength Method of AISI Spec.
Appendix 1 to predict nominal strength (Mn) using the
elastic buckling results
• Know where to go to learn more:
www.ce.jhu.edu/bschafer and DSM Design Guide
DSM
• Mechanics replace empiricism
• All member limit states are addressed in one method
• Any cross-section can be studied, thus realizing one of
the great potentials of cold-formed steel
• Avenues for new products without exhaustive testing
• Rediscover the technology product/market of metal
buildings instead of the commodity market
• The main AISI Specification, over the years, has
contributed to creating a level playing field for metal
building companies, but one that does not allow a great
deal of innovation – with DSM in place a new playing
field has just been opened up!
• New distortional buckling provisions are onerous and
best completed with DSM instead. Done right,
distortional buckling can have little impact on strength
• Only simple lip edge stiffeners allowed in Main
Specification now
• Remember that new DSM playing field? Someone is
going to go there, what happens to those who don’t?
• How long until European, Australian, Asian? companies
bring their sections here and demonstrate why they
improved/optimized their sections years ago
www.crystal-cure.com
• DSM can reasonably be traced to a conference presentation in
1998, in less than 10 years it has come to the AISI Specification
• In 10 more years DSM will become the preferred method for
cold-formed steel strength prediction
• This opens the door to further use of computational tools in coldformed steel design
• Research is happening from many different directions, but true
and accurate virtual models of buildings are in the works (10 to
20 years?). Metal buildings are going to be first in line because
they have (1) participated in and funded some of the research,
and (2) because their more regular nature makes them a good
place to start. How will the industry take advantage of this?