Plate formed section instead of rolled section

[senthil83]

Dear all,

we are using UB 203x133x30 section size for our supporting beam of s355jo material,
due to non-availability section, our shop is asking for the deviation to make the
ub section size using plates of s355jo material for the same thickness and size as specified for UB section.

can we use plate formed section instead of rolled section? we are using is:800 code for designing the beam

is this affect the strength of the beam member we are using. How to calculate the reduced strength?

Thanks
senthil

 

[frv]

Look up plate girder. They used to be designed quite frequently in the US some years ago. less common today. There are some checks that need to be performed above and beyond what you would typically check for a rolled section. Additionally, you need to size the flange to web welds.

 

[ishvaaag]

You will have to follow the standing specs for built-up members in your region, quite likely Indian Standard 800:2007

http://www.nitsri.net/civil/course-material/IS 800-2007.pdf

It seems major effect in design is through classification of the section as more or less slender and maybe assignation of typified residual stress (I have not direct knowledge of IS), what depends on if rolled or built-up.

 

[racookpe1978]

How many linear feet need be maufactored this way? Can you use an alternative beam that is available?

Building up from a plate sections is possible, but takes man-power/foot much more dollars.

If you do build it up, make sure your jigs and fixtures are very rigid against movement: alignment of the webs and flanges is essential - in most cases easier to screw up than the welds even - if you are to get the same strength. That is, even a intermittent fillet weld will likely be strong enough, but an uneven or twisted flange is deadly.