Fixed End Moment - Clockwise or Anticlockwise?

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In summary: So , fixed end moment is the reaction moment?In summary, the book and the Wikipedia article have conflicting information about the direction of the fixed end moment on the left and right spans of the beam. This is because the book is discussing the equivalent moment of the beam loading, while the Wikipedia article is referring to the wall's reaction moment. Both cases assign clockwise moment as positive, but this leads to different answers when drawing the bending moment diagram. It appears that the fixed end moment is the reaction moment, which is equal in magnitude and opposite in direction to the equivalent moment of the beam loading.
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Homework Statement



In the book (photo 1 ) , it's stated at the left span, the fixed end moment is clockwise , while on the right span , the fixed end moment is anticlockwise . But , accroding to wiki (photo2) , it's stated that at the left span of the beam , the fixed end moment is anticlockwise , while on the right span , it's clockwise ...

In both cases , clockwise moment is assigned as positive . Which case is correct ? I'm confused . ht//en.wikipedia.org/wiki/Fixed_end_moment

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The Attempt at a Solution



IMO , only one of it an be correct . This is because as the In both cases , clockwise moment is assigned as positive . When we drawing the bending moment diagram , it will lead to different answer . [/B]
 

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  • #2
It looks like the book is talking about the equivalent moment of the beam loading (note the circular arrow is on the beam side). The Wikipedia article appears to be referring to the wall's reaction moment to the beam loading. Note that you should expect these two moments to be equal magnitude and opposite direction, since the beam has not been caused to spin.
Similarly, when you are standing on the ground, often we talk about your weight as a force pushing down on the ground. But there is also the equal force of the ground pushing up on you, keeping you from falling into the ground.
 
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scottdave said:
The Wikipedia article appears to be referring to the wall's reaction moment to the beam loading. Note that you should expect these two moments to be equal magnitude and opposite direction, since the beam has not been caused to spin.
So , fixed end moment is the reaction moment ?
 
  • #4
fonseh said:
So , fixed end moment is the reaction moment ?

That is what it looks to me, in the Wikipedia article is referring to, the way they drew the arrows.
 

1. What is a fixed end moment?

A fixed end moment is a type of bending moment that occurs at the end of a structural member that is fixed or rigidly attached to another member. It is caused by an external force or load acting on the member and can result in bending or twisting of the member.

2. What is the difference between clockwise and anticlockwise fixed end moments?

The direction of a fixed end moment refers to the direction in which the structural member is being twisted or bent. A clockwise fixed end moment causes the member to twist or bend in a clockwise direction, while an anticlockwise fixed end moment causes the member to twist or bend in an anticlockwise direction.

3. How do you determine the direction of a fixed end moment?

The direction of a fixed end moment can be determined by looking at the external forces acting on the structural member. If the forces are acting in a clockwise direction, the fixed end moment will also be clockwise. If the forces are acting in an anticlockwise direction, the fixed end moment will be anticlockwise.

4. Why is it important to know the direction of a fixed end moment?

The direction of a fixed end moment is important because it can affect the stability and strength of a structure. Knowing the direction of the fixed end moment allows engineers to properly design and reinforce the structure to withstand the external forces and prevent failure.

5. Can a fixed end moment change direction?

No, a fixed end moment cannot change direction. It is determined by the external forces acting on the structural member and will remain in the same direction unless the forces change. However, the magnitude of the fixed end moment can change depending on the magnitude and direction of the external forces.

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