How to check the plate with concentrated force?

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Discussion Overview

The discussion revolves around the analysis of a plate with two edges fixed by welds and subjected to a lateral concentrated load. Participants explore the implications of the design, the adequacy of the provided drawings, and the stresses on the welds. The conversation includes technical considerations related to welding, load distribution, and structural integrity.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the adequacy of the design based on the provided drawings, suggesting that there is insufficient information for a proper analysis.
  • Another participant, with welding experience, emphasizes the importance of considering various factors such as weight, lateral stress, axial stress, and material properties when analyzing the welds.
  • Concerns are raised about the consistency of the drawings, with some participants noting discrepancies between different views of the welds.
  • A participant expresses uncertainty about how the lateral load is distributed between the two welds and mentions the complexity of thick plate theory.
  • There are discussions about the need for detailed fabrication information and adherence to welding codes, with references to AISC and ASME standards.
  • One participant shares insights from experience, noting that welds subjected to loads often fail at the edges and stresses the importance of good penetration and procedural guidelines to avoid failures.

Areas of Agreement / Disagreement

Participants generally express disagreement regarding the adequacy of the design and the clarity of the drawings. Multiple competing views remain about the interpretation of the drawings and the factors influencing weld strength and load distribution.

Contextual Notes

Limitations include missing assumptions about load distribution, the need for clearer drawings, and unresolved details regarding the welding process and standards. The discussion highlights the complexity of analyzing the structural integrity of the welds under lateral loads.

atlas_2010
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Hello all,
I have a question about the plate with two edges fixed by weld and subjected to lateral conconerated load, as the following picture shown, I am not very familiar with plate theroy, Could you give me a soluation about this weld?
Given,
L1 Weld 1 Length
L2 Weld 2 Length
t Weld throat
Ft Lateral load
L3 Force arm to weld 1
L4 Force arm to weld 2

Soluation
The weld stress

Thank you.
 

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The drawing comes up on screen too small to see properly .
 
Nidum said:
The drawing comes up on screen too small to see properly .
Hello, Nidum
Thank you for your comment.I have made a PDF file, please find the attachment and give your solution.
Thanks again.
 

Attachments

Having studied your drawing I regret that I must decline to help further .

The design does not seem to be based on sound engineering principles and in any case there is not enough information given for a proper analysis .
 
I was a welder and fabricator for years and based on the drawings you provided there is just not enough information included to really see (visualize in detail) any proper load bearing area. Just from the drawing it looks like a stand off lifting lug. You have a lot of different things to consider, weight, lateral stress, axial stress (x,y,c) material tensile strength and welding process itself. Anytime you weld a piece of metal you heat it to the melting point and each times is cools the crystalline structure of the metal itself changes (ie it hardens and becomes more brittle) You should probably take a few detailed pictures of a finished product point out all fillets and describe your process, gaps, angles penetration depth ext. It is being welded to code? if so what standard? ASME ext.
 
The drawing doesn't make sense to me -- the 3 views don't seem to be consistent with each other...
 
berkeman said:
The drawing doesn't make sense to me -- the 3 views don't seem to be consistent with each other...

It took me a while - I think the L shape is a view of the weld bead detached from the structure .
 
Nidum said:
It took me a while - I think the L shape is a view of the weld bead detached from the structure .
Ah, that helps some. But his front view and bottom(?) views don't seem to match either. It looks like there is some sort of a base in the front view, that is missing in the bottom view...
 
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This bracket must be attached to something so I would expect to see some bolt holes .

The fact that the load appears to go from thick section to thin section to nowhere was my main concern with this design .
 
  • #10
Nidum said:
Having studied your drawing I regret that I must decline to help further .

The design does not seem to be based on sound engineering principles and in any case there is not enough information given for a proper analysis .

Sorry for miss information and not clear description.
This is a interface joint, we supply the main plate, the back structures are supplied by others, so bo be safe I need to ensure the plate can hold all force, I know it is not good to subject the lateral load, but I have no other choice, so need some stiffener.
But now I need to konw how much the stress on the weld which block me a long time.And then I can decide the stiffener size.
 
  • #11
gjonesy said:
I was a welder and fabricator for years and based on the drawings you provided there is just not enough information included to really see (visualize in detail) any proper load bearing area. Just from the drawing it looks like a stand off lifting lug. You have a lot of different things to consider, weight, lateral stress, axial stress (x,y,c) material tensile strength and welding process itself. Anytime you weld a piece of metal you heat it to the melting point and each times is cools the crystalline structure of the metal itself changes (ie it hardens and becomes more brittle) You should probably take a few detailed pictures of a finished product point out all fillets and describe your process, gaps, angles penetration depth ext. It is being welded to code? if so what standard? ASME ext.
Thank you for your guidence.
And sorry for miss information and not clear description again.
This is a simple sketch,I remove a lot of thing for clear,and I am foucs on the strength, the fabrication detail will be added later.
This is based on AISC rules, probably similar with ASME, can you show me which part of ASME I can find the related requirement?
 
  • #12
berkeman said:
Ah, that helps some. But his front view and bottom(?) views don't seem to match either. It looks like there is some sort of a base in the front view, that is missing in the bottom view...

Sorry for miss information and not clear description and thank you for your attenation.

The L view is intened to show the weld seam information.This is a interface joint, we supply the main plate, the back structures are supplied by others, so bo be safe I need to ensure the plate can hold all force, so I remove the base in the bottom view.
 
  • #13
Nidum said:
This bracket must be attached to something so I would expect to see some bolt holes .

The fact that the load appears to go from thick section to thin section to nowhere was my main concern with this design .
totally agree with you.One part of the force will go to weld 1 and the other go to weld 2, but I don't know the exactly percent data. And I look up the thick plate theroy, it is very complex, I thick somewhere will show a moment disbutriction factor.
 
  • #14
atlas_2010 said:
Thank you for your guidence.
And sorry for miss information and not clear description again.
This is a simple sketch,I remove a lot of thing for clear,and I am foucs on the strength, the fabrication detail will be added later.
This is based on AISC rules, probably similar with ASME, can you show me which part of ASME I can find the related requirement?

http://www.gowelding.com/wp/asme4.htm

I will tell you from experience welds subjected to loads (if they fail) tend to break at the edges this is true for most types of welds with the exception being socket welds subjected to torque. And tig welds that are fused without filler, (they sometimes break right in the middle). Good penetration and adequate procedural guidelines should be sufficient to avoid a weld failure. My old foreman use to tell me 'if you aren't confident in your finished product don't put your stamp on it". In other words review your steps and have a foreman or Quality control specialist check it before you stamp it. It will pass that way.
 
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