> From: "vicpeng" <vicpeng(--nospam--at)vtcg.com>
> Do US jurisdictions accept projects using Canada's LS design method?
> From: Peter Higgins <JillHiggins(--nospam--at)compuserve.com>
> In a word: No.
> However, the laws of physics are the same south of the border as they are
> north of it. A good design there is also a good design here. Nothing stops
> you from designing in limit states and "converting" the result to look
> like it came from LRFD (or ASD for that matter). Indeed, this is what I
> often do. All you did is take a different (and easier) path to the same
Hmmmm. True, the laws of physics are the same but the goals of the
design standards and building codes may be different. Future
incarnations of limit states standards will permit the designer to
balance the risk and economics of design based on locality. It is not
LRFD factors are different than Canadian so it would be a struggle to
prove such an equivalence. If you need to know LRFD well enough to make
a prima facie conversion, you may as well design to LRFD. In any case,
most major design/analysis software supports LRFD.
In Canada, the building codes reference the limit states steel design
standard (S16.1) which explicitly excludes the use of other design
standards (S16, ASD, LRFD). It took 20 years from the introduction of
the S16.1 to completely exclude stress design (S16) as an option.
However, S16.1 allows an alternate rational design method as acceptable
if the designer can prove that the marginal factors of safety are at
least equal to those in the standard. In other words, if the design is
controlled by service level conditions, then the strength limit states
are satisfied. However, this may not apply to all aspects of the design
of a structure or even all details on a member.
I am aware of projects in Canada that have had occupancy permits
withheld due to the inability of the EOR to provide such proof (usually
ASD designs sold into Canada, professional licences lost, etc.).
Eurocode tends to be more rigourous than US/Canadian and is checked more
strictly at the authority level.
So, although the laws of physics are the same, you may as well use the
local standards if you intend to attempt some level of conversion.
Paul Ransom, P. Eng.
Burlington, Ontario, Canada