Analysis & Design of Weld Groups



Excel Template for the Analysis & Design of Weld Groups Subjected to Simultaneous Shear, Bending, Torsion & Axial Loading. Weld configuration can be any shape of multi-linear weld lengths in a plane. If present, unsymmetrical bending is taken into account in the analysis.
Dr Shaiq Khan is a Chartered Structural Engineer working freelance in the building trade. In his day to day work, he develops and uses computer software for the design and maintenance of buildings. This enables him to enhance the quality of work for his clients. It also shares and enhances technical expertise with fellow professionals in this country and abroad. More details at his website.

Calculation Reference
Weld Strength Analysis

The analysis and design of weld groups subjected to simultaneous shear, bending, torsion, and axial loading can be quite complex. Here is a step-by-step guide to approach the problem:

  1. Determine the loading conditions: Identify the external loads (shear, bending, torsion, and axial) acting on the weld group. These loads can be obtained from the structural analysis of the entire structure.

  2. Calculate the resultant force and moment: Combine the individual external loads to find the resultant force (R) and moment (M) acting on the weld group. The resultant force and moment will be used to calculate the equivalent stress on each weld.

  3. Establish the weld group geometry: Determine the weld group's geometry, including the number of welds, weld length, weld size, and weld spacing. This information will be used to calculate the weld group's capacity.

  4. Calculate the equivalent stress on each weld: For each weld in the group, calculate the equivalent stress caused by the combined external loads. This can be done using the following equation:

σ_eq = sqrt(σ_axial^2 + 3*(τ_shear^2))

where σ_eq is the equivalent stress, σ_axial is the axial stress, and τ_shear is the shear stress on the weld. Note that this equation assumes linear elastic behavior and is based on the von Mises yield criterion.

  1. Check the weld capacity: Compare the equivalent stress (σ_eq) on each weld with the allowable stress for the weld material. The weld group is considered safe if the equivalent stress is less than or equal to the allowable stress for all welds.

  2. Iterate the design, if necessary: If the weld group does not meet the capacity requirements, adjust the weld size, weld length, or weld spacing to increase the capacity. Repeat steps 4 and 5 to check the new design.

  3. Verify weld group geometry: Ensure that the weld group's geometry meets the applicable code requirements for minimum spacing, edge distances, and weld length-to-width ratios.

  4. Detailing and fabrication: Once the weld group design is finalized, provide the necessary detailing and fabrication information, including weld type, weld size, weld length, weld spacing, and weld material.

Always consult the relevant design codes and standards for specific requirements, limitations, and procedures when designing weld groups subjected to simultaneous shear, bending, torsion, and axial loading.

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25 Jan 2010
Last Modified
28 Apr 2023
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507.00 Kb
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File Author:
Shaiq Khan

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Comments: 9
technouk 14 years ago
Just to close off; the recent submission of an updated file by the Shaiq Khan has resolved the issue. The spreadsheet is now fully functional and does just what I need. Thanks!
shahrokh 14 years ago
technouk 14 years ago
Shaiq emailed an updateThe updated calculation has an option to find stress resultant using SRSS OR EuroCode (Von Mises) formula.
technouk 14 years ago
Phil this is a useful resource it may be what you are looking for:Biaxial Stress Assessment.xls
technouk 14 years ago
Thanks for the reply John. The cell I need to change is actually provided as an option for the user (as a drop-down box), but (perhaps inadvertently) has been locked so that the drop-down selection cannot be changed.Perhaps I'll try the
technouk 14 years ago
Excel protection is so easy to break it is barley worth setting. A google search will show 1000's of pages outlining how to break them. See Gimpsey and Associates solution - passwords hacked in the blink of an eye.
technouk 14 years ago
technouk spreadsheets are generally password locked which keeps them safe from modification but difficult to modify for your own needs. There are a couple of other repository items which I think you will find both useful and easy to modify:1) WELDGRP.xls - One of Alex Tomanovich's great spreadsheets. They are protected but not with a password. Just download and unprotect worksheet. There are elastic and ultimate strength methods. A metric version can also found here WELDGRP Metric.xls.2) LineSec.xls - This is good for any section made up of lines, welds lines included. I find it useful because the weld line does not have to be the same thickness each line can have its own thickness property. Analysis is elastic. This calculation is mine and all the working is shown with XLC equations so it should be easy to modify.3) ThinWallProp1.xls is a great calculation from Yakov Polyakov. This will give the ultimate strength of a weld line. From memory I think all lines have the same thickness.One or other of these methods has got me out of all the weld static strength problems I have encountered.
technouk 14 years ago
This spreadsheet looks to be an excellent resource. I can't seem to change the Equivalent Stress Calculation Method from SRSS to Von Mises (cell is protected and sheet has password protection).Any ideas anyone?Phil
yosso 15 years ago
British standards, but an excellent resource.