Shear strength of a cut I-beam

In summary, the beam must be able to support the design loads and any additional loads that may be placed on it. It is also important that the beam remain in compression and not buckle. If the beam does buckle, it may cause the structure to fail.
  • #1
vernierdesign
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Hello, I'm in the process of building a 2 story townhome project and had a question on a beam. The structural engineer is calling for a cut I-beam on top foundation which spans over the garage (10') and the load will be placed on just the top flange (see attached). The structure will cantilever 6' over this beam and I'm curious on the shear strength of the beam with this type of alteration.
 
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  • #2
There is no attached ...
In a span, buckling of the top flange must be controlled.
In a cantilever, buckling of the lower flange must be controlled.
 
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  • #3
If you want to cross check the engineer, you need to calculate the following:

1) The design loads on the beam. Your building code specifies design loads and safety factors, which could be snow, wind, earthquake, equipment, people, etc.
2) Buckling of whichever flange is in compression.
3) Yielding of flanges.
4) Web crippling.
5) Bearing stress at support points.
6) Shear in web.
7) Deflection, and its effect on the structure.
8) Strength of connections.

A good resource is the AISC Steel Construction Manual. Note that this manual assumes a background consisting of several engineering courses, so our ability to help you is quite limited. Especially in the context of an internet forum.
 
  • #4
Thank you for your response... I know there's many variables to this question but I'm trying to just focus on the bearing stress of the top flange.

The pic that I attempted to download shows that the lower flange and web is cut back 8" on both sides of the beam so the beam would fit between the foundation over the garage entrance. Then top flange will extend 8" over to top of the foundation. The top flange will be welded to a beam plate that's embedded in the concrete on the top of the foundation. There will be no support under the web/lower flange. So, the the weight of the structure will essentially resting on the top flange. The engineer is calling out for a w10x19 beam.

Any thoughts on this would be greatly appreciated.
 
  • #5
vernierdesign said:
The pic that I attempted to download
Try the "Attach files" link below the Edit window to upload a JPG or PDF file with the image.

You may also be able to drag and drop the image into the Edit window as another way to attach it to a Reply.
 

Related to Shear strength of a cut I-beam

1. What is shear strength?

Shear strength is the ability of a material to resist forces that are applied parallel to its surface, causing it to slide or shear.

2. How is shear strength measured?

Shear strength is typically measured in pounds per square inch (psi) or newtons per square millimeter (N/mm²).

3. What factors affect the shear strength of a cut I-beam?

The shear strength of a cut I-beam is affected by the material properties of the beam, such as its yield strength and ductility, as well as the size and shape of the cut and the orientation of the cut relative to the direction of the applied force.

4. How is the shear strength of a cut I-beam calculated?

The shear strength of a cut I-beam can be calculated using the formula: Shear strength = 0.6 x Yield strength x Area of the remaining section. This formula takes into account the reduction in area due to the cut.

5. Can the shear strength of a cut I-beam be increased?

Yes, the shear strength of a cut I-beam can be increased by reinforcing the cut section with additional material, such as a steel plate or angle iron. This can help distribute the applied force and prevent the beam from shearing at the cut.

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