# Stresses in Beam



## MaryJ (Mar 27, 2013)

Could someone let me know if I am correct on these statement. My coworker asked me and am not 100% clear on the fact anymore.

1) Max Shear stress occurs at the centroid of a beam section

2) Max compressive stree occurs at the top of a beam

3) Bending stress is maximum at the outer edge of a beam and is zero at the neutral axis.

4) Horizontal Shear stress is zero at the outer edge of a beam.


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## MA_PE (Mar 27, 2013)

Assuming your questions are for a homogeneous rectangular beam on simple supports with a vertical load on the top.

1) The maximum shear load will be at the support, the maximum shear stress is at the neutral axis, no necessarily the centroid.

2) The maximum compressive stress due to bending would occur on the opposite face from the tension side. For a vertically loaded beam, the maximum compressive stress would be at the top. If the beam were subject to pure compression at it ends with no bending, then the compressive stress would be uniform through out the crossection.

3) The maximum tension stressdue to bending would be at the outer edge on the tension face. Bending stress is zero at the neutral axis.

4) Yes, shear stress is zero at the outer edge of the beam.


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## KevinNg (Mar 27, 2013)

Good job MA_PE.

I have no better answer than MA_PE and agreed with MA_PE.


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## Ble_PE (Mar 28, 2013)

To go along with what MA said, here are some diagrams which you should be able to find in any mechanics of materials book:


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## MaryJ (Mar 28, 2013)

Thanks to all for helping!


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## kevo_55 (Mar 28, 2013)

Fancy drawings Ble!

Now, what book did you get them from? :Chris:


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## Ble_PE (Mar 28, 2013)

From the great book of google... h34r:


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## kevo_55 (Mar 28, 2013)

I like that answer!


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## MA_PE (Mar 28, 2013)

rect beam? damn near killed it.


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## Judowolf PE (Mar 28, 2013)

I know I'm a lowly EE, but I use a free/almost free software series for calculating stress/strain...mdsolids. Anyone else use this?


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## Judowolf PE (Mar 28, 2013)

The drawings reminded me of it, I haven't used it in a while though!


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## pbrme (Apr 23, 2013)

Judowolf PE said:


> I know I'm a lowly EE, but I use a free/almost free software series for calculating stress/strain...mdsolids. Anyone else use this?


I used that in college. Helped for generating quick shear-moment diagrams. I've done enough of them now I just hand sketch.


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