Determining Required Weld Strength

[Brandnew]

This looks like a great forum. I have a question as to something I have not encountered in my SHORT career but would like to know.

How does one determine the weld strength required when welding a plate (or any other shape) to the bottom flange of a beam? Top flange? Is it the same strength for each flange?

Since the beam is in bending I've always wondered what force should be used to design the weld. I've figured you would design for the maximum shear strength, but as I said, I haven't had to do this before.

As you can tell I don't design welds often but I would still like to know this.

All comments appreciated.

 

[FM1]

Hi,

I think the best thing to do (which will really visulize the concept for you) is to get a hold of a bridge design manual ( old USS or AISI Highway Structures Design Manual, probably on a shelf in every office) or a bridge design book ( eg bridge engineering by Tanias) which contains design examples where cover plates are added to bottom and somtimes top flanges of steel girders, and follow the analysis and design steps. I think there are also provisions in AISC for cover plates though I am not certain.

Much luck and success

 

[redhead]

Design of Welded Structures - Blodgett, published by Lincoln Arc Welding Foundation is the "bible " on this subject.

 

[section]

The force in the weld is calculated from the well known formula S a y / I. This gives the force per unit length of weld. Divide by two if there is a weld on either side of your flange plate.

 

[DaveVikingPE]

Purchase Blodgett's book as per redhead. It's $10 and available from Lincoln Arc Welding Company -

http://www.lincoln.electric.com.

 

[Brandnew]

Thanks for the responses. I got my books on order. I ordered "Design of Welded Structures" and "Design of Weldments".

Here's a direct link to the books:

https://ssl.lincolnelectric.com/lincoln/store.asp?PID=16&cat=7

Thanks again!

 

[Imagineer]

The "Manual of Steel Construction, LRFD 2nd Ed.; Vol. II:Connections" has some pretty good examples of just this sort of thing. I'm not sure if the same examples are in the new 3rd Ed. but you get a year's free AISC membership if you purchase it before April. Imagineer