huangyhg

us shapes versus british shapes
folks,
i have run into a very weird situation and seek your input.
i am designing a fairly significant steel structure in the middle east and requires sizeable members for the trusses.
in the us, typically w14's are available in a wide range of weights. however, the british sections are very limited in their options.
how do engineers in britain deal with this problem? for a very simple example, i need a lot of w21x44 and w24x55 for floor beams. the british equivalent sections only start at w24x68 (ub610x229x101) and w21x55 (ub533x210x82)leading to considerable expense.
what is the workaround? have any of you encountered such a problem?
thanks
the british standard bs4-1:2005 lists the 'standard' range. and you are correct the bs does not have direct equivalents for all of your us sections.
however, corus (possibly others) do manufacture us section sizes in accordance with astm a6/a6m. these are supplementary to the bs. i do not know how popular they are but you state you need a lot of them so i suggest maybe you contact corus.
the equvalents are w21 x 44 = 533 x 165 x 66ub; w24 x 55 = 610 x 178 x 82ub.
ussuri,
i contacted corus usa this morning and i was told that they currently don't manufacture us equivalent metric shapes because of the economy and exchange rates.
corus stated that they might start producing but was not definitive about when.
is it worth contacting corus europe (uk or netherlands)?
in answer to your first question, the get around is to design using the sections available and modify the deaign. if the smaller ub is no good and the next size up was way too large, it provides scope for amending the structural layout to make it more efficient. increasing spans, increasing spacing etc.
ussuri,
thanks. i will try corus europe. however, i found that corus now manufactures advance sections which have a smaller w21 and w24. they are designated as ukb's
those are fairly new. a requirement dicated by the european construction products directive.
there is a fundamental difference that no-one has yet mentioned:
in the us w shapes are used as both columns and beams and the range of weights allows for this.
in the uk the ub stands for universal beam and is as such more for use of beams. there are heavier column sections designated as ucs that are more appropriate for columns. the combination of these two types will give you something closer to the range of the us sizes.
i have not found the british sections limiting in their options - unless i am missing something the difference in wt between w21x44(at 65.4 kg/m) and ub533x165x66 kg/m and w24x55 ( 81.8 kg/m) and ub 610x178x82 kg/m is insignificant.
as far as middle east jobs, we did in quite a few cases purposely change from the more comprehensive british sections to a lesser range of european ( hea, heb etc) but that was purely because price and delivery more than offset the added weight. i would say that availability and price usually ended up being more relevant than a difference in weight.
xxpegasus,
are the ub sections you are mentioning readily available? also, is that section found in bs 5950?
thanks
the reason i ask is because in one of corus's publications, i find the following footnote.
dimensions and properties to bs4-1:2005.
these dimensions are in addition to our standard range of bs4 sections.
does this mean that these sections are available inspite of them not being listed in bs4?
thanks
looking at the corus "blue book" (available by the way from their website) you are correct that these particular sections are not in bs4. this isnt a problem in itself as obviously the sections can be used as normal in accordance with bs5950. they do however seem to feature in corus list "for uk" so i cant really say whether they would be available easily for overseas - corus uk/europe should be contacted to clarify this.

__________________
借用达朗贝尔的名言：前进吧，你会得到信心!
[url="http://www.dimcax.com"]几何尺寸与公差标准[/url]