Doubler plate for Tubular connection 1

[peter44]

The doubler plates are used quite often for secondary attachments weld to main structure and the temporary connection. But i have the following questions about it:
1.why use doubler plate? Is it used to make the cutting of the attachemnts more easy? If so, can we cut the temporary 3mm awary from the parent material to avoid damage the chord(not use doubler plate)?
2.If a doubler plate is used, it can resist more axil compression, but can it resist tension or bending?
3.If doubler plate can resist tension of bending, how to calculate weld size and check the thickness of the doubler plate?

The above puzzle me a lot, hope someone can help.

 

[BigInch]

1. Reduces stress concentrations by adding more area.
2. It can resist compression, shear and tension.
3. Same as any welded connection.

This ASCE paper might do you some good,

http://scitation.aip.org/getabs/ser...00128000011001399000001&idtype=cvips&gifs=yes

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[peter44]

Biginch, thank you for your answer.
Do you mean that a doubler plate is not necessary if the punching shear is enough even the brace is a temporary brace?

 

[BigInch]

There are a number of ways doubler plates can be used as a joint reinforcement, so it would be good to see a diagram of the connection. Can you post a sketch somewhere?

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[BigInch]

Do you have flat or a curved plate? Any more hints?

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[peter44]

Biginch, The problem is for a pipe to pipe connection, so it's a curved plate.
Most articles say that the doubler plate will increase the ultimate strengh of joint whether the brace is compression or tention brace(they do fem analysis and experiment).
I think the doubler itself and the weldment between the doubler and the chord should be checked, but i don't know how to check, and if there are some formulars to check?
I have not found articles on this problem, hope someone can help.

 

[BigInch]

Peter, Its been a long time since I've actually designed a connection, so why not see if you can get some advice from the structural engineers? There is a forum specifically for structural.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[swearingen]

There is a commonly used way to get around doublers at a pipe connection to save money. Use thicker pipe at the connection and then neck the pipe to thinner wall a few feet away from the connection. This effectively gives you a doubler at much less cost and complexity. It also allows you to use standard formulas to calculate stresses at the connection because you're using standard pipe.