Engineering Is this moment a bending or a torsion?

AI Thread Summary
The discussion revolves around the classification of a moment acting on a beam as either bending or torsion. Participants clarify that while the moment appears to induce rotation in the Z direction, it can still be considered torsion due to the shearing loads on the welds, which depend on their distance from the center of the moment. The welds are noted to resist pure shear loads, and the effectiveness of the welds is linked to the weld metal strength and the welder's skill. The conversation emphasizes the complexity of analyzing forces in structural engineering. Ultimately, the moment can technically be classified as torsion based on the shearing load dynamics.
Amaelle
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Homework Statement
look at the image
Relevant Equations
torsion vs bending
Greetings!
1650474068323.png


As you could see the moment try to make beam to rotate in the support plane with the wall which mean for me this moment is on the Z direction but the longitudinal axis is the X direction and I know that for a moment to be torsion it needs to be in a longitudinal direction, but the solution says it´s a torsion! any help would be highly appreciated thanks!
 
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It seems that the 100x12 plate is trying to rotate about an axis that is perpendicular to the 100x12 face.
That makes both welds resist pure shear loads.
 
Amazing! clear now, but it´s not torsion right?
 
Amaelle said:
Amazing! clear now, but it´s not torsion right?
Technically, it can be considered torsion, because the magnitude and direction of the shearing load for each section of the welds (along L) depend on the radius or distance between it and the center of the moment M.
 
Lnewqban said:
That makes both welds resist pure shear loads.
I agree.
It is a couple.
The shear is in the contact zones of the welds which have an area of contact with the plate. But the mid-plane of the flat surface weld has an area of only 1/√2 = 70%.
So the strength will come down to the strength of the weld metal, and the skill of the weldor.
 
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Lnewqban said:
Technically, it can be considered torsion, because the magnitude and direction of the shearing load for each section of the welds (along L) depend on the radius or distance between it and the center of the moment M.
I was thinking the same thing after you pointed out to the shear forces! thanks a million!
 

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