Resultant moment of beam fixed at one end

[SubZer0]

TL;DR Summary

Clarification of terminology

Hi all,

I just wanted to get some clarification on 'resultant moment' when calculated in 2D for a beam which is fixed at one end (point A), and has a load applied at the opposite end (point B). My interpretation of 'resultant moment' would be calculated as sum(M) = Ma + FL, where Ma is the reaction moment at the fixed end of the beam, F is the external force applied and L is the perpendicular distance between the applied load and point A. So in my understanding, the resultant moment about point A would simply be -FL, or the opposite of the sum of moments about point A.

Is this is a correct assumption?

Thanks!

 

[SubZer0]

Actually, thinking more about this, the resultant moment would simply be the sum of the moments about point A, and would not include the reaction moment at the fixed end. So above, the resultant moment would simply be sum(M)=FL.

 

[PhanthomJay]

Summary: Clarification of terminology

Hi all,

I just wanted to get some clarification on 'resultant moment' when calculated in 2D for a beam which is fixed at one end (point A), and has a load applied at the opposite end (point B). My interpretation of 'resultant moment' would be calculated as sum(M) = Ma + FL, where Ma is the reaction moment at the fixed end of the beam, F is the external force applied and L is the perpendicular distance between the applied load and point A. So in my understanding, the resultant moment about point A would simply be -FL, or the opposite of the sum of moments about point A.

Is this is a correct assumption?

Thanks!

It depends on what you mean by resultant moment. The resultant moment of the applied force about A is +FL. The resultant fixed end moment is -FL. The resultant moment on the beam as a whole is 0, for equilibrium. The term resultant is usually used when there is a distributed load and you want to find its resultant acting as a point load. Otherwise it may be best to stay away from that term and consider moments and forces separately in the x and y directions.