shrinkage of large girders with stiffeners
shrinkage of large girders with stiffeners
(OP)
Hi, I'm looking for a small formulae or some rules of thumb to predict the longitudinal shrinkage of large girders (mostly for bridges). We use only fillet weld. I know that shrinkage can be produce by the web-flange welds, the flange-stiffener welds and the web-stiffeners welds. All the formulae given in Blodgett or in Lincoln are not representative of our experiences. It always shrinks a lot less than what those formulae tells us.
For the web-stiffener welds, I have to be able to draw, on the flanges, all the places were the stiffener goes before anything is welded.
thanks
For the web-stiffener welds, I have to be able to draw, on the flanges, all the places were the stiffener goes before anything is welded.
thanks





RE: shrinkage of large girders with stiffeners
RE: shrinkage of large girders with stiffeners
If a could calculate the shrikage made by one fillet weld, I'd multiply this by 4 to have the shrinkage of one stiffeners. With that, I'll be able to draw the lines were the stiffeners goes, a little bit in front of were it would be without the shrinkage. (for example,if one weld cause .35mm of shrinkage, one stiffeners cause 1.4mm. So the first one will be in front by 0.7mm, the second one will be in front by 2.1mm and the 15th one will be in front bye 20.3mm. The all girder will be smaller by 21mm)
What can I say more... we mostly use SAW on 350AT steal, usually the preheating T° is 100°F, all the other parameters always changes, so all those parameters should be in the formulae.
I hope this help. I know I'm not to good in english but if there's some other questions, don't be shy, I'll try my best to answer it since I'll do anythng to solve my problem.
thanks
RE: shrinkage of large girders with stiffeners
http://www.forengineers.org/pvrc/wrcpvrcbulletin.htm
RE: shrinkage of large girders with stiffeners
RE: shrinkage of large girders with stiffeners
The problem with predicting distortion is that it is dependant on so many variables and it will occur in all three dimensions, causing twisting as well as shrinkage. Try to position joints near the neutral axis of the fabrication and try and balance the welding; wherever possible form items rather than weld plates together. Also try putting assemblies back to back so that the distortion in one pulls against the other.
I think the easiest solution is to embark upon your own research, do some trials on scrap and see what sort of distortion levels you get.
Regards
John www.gowelding.com