Fixed End Moment - Clockwise or Anticlockwise?

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Discussion Overview

The discussion revolves around the concept of fixed end moments in beams, specifically addressing the direction of these moments (clockwise or anticlockwise) as presented in different sources. Participants are examining the implications of these definitions in the context of bending moment diagrams and structural analysis.

Discussion Character

  • Homework-related
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant notes a discrepancy between their textbook and Wikipedia regarding the direction of fixed end moments, expressing confusion over which source is correct.
  • Another participant suggests that the textbook may be discussing the equivalent moment of the beam loading, while the Wikipedia article refers to the wall's reaction moment, indicating that these moments should be equal in magnitude but opposite in direction.
  • A later reply questions whether the fixed end moment can be considered a reaction moment, reflecting on the implications of the definitions used in the sources.

Areas of Agreement / Disagreement

Participants do not reach a consensus on which source is correct regarding the direction of fixed end moments. Multiple competing views remain regarding the interpretation of the moments as either equivalent to beam loading or as reaction moments from the wall.

Contextual Notes

The discussion highlights potential limitations in understanding due to differing definitions and representations of moments in various sources. There is an unresolved ambiguity regarding the assumptions made about the moments and their representations in diagrams.

fonseh
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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

Homework Equations

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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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 ?
 
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.
 

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