Shearing/Bending diagrams, forces acting on beam

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Discussion Overview

The discussion revolves around the analysis of forces acting on a beam, specifically focusing on computing reactions at supports, drawing shearing force and bending moment diagrams, and determining the maximum values of shearing force and bending moment. The context is primarily homework-related, involving the application of free body diagrams and relevant equations.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about their approach to drawing shearing and bending diagrams and seeks confirmation on their correctness.
  • Another participant points out a discrepancy in the loading and shear diagrams, questioning the presence of three discontinuities in the shear diagram when only two point loads are shown.
  • A participant inquires whether a beam fixed to a wall should be treated differently than one simply resting on a pivot.
  • One participant shares an updated attempt at the bending moment diagram but still feels unsure about their approach.
  • Another participant notes that the shear diagram indicates two steps, suggesting that there should be corresponding slopes in the bending moment diagram, and clarifies that the built-in end supports a moment, affecting the moment diagram's behavior.

Areas of Agreement / Disagreement

Participants express differing views on the accuracy of the diagrams presented, with some pointing out specific errors and others seeking clarification on treatment of boundary conditions. The discussion remains unresolved regarding the correct representation of the diagrams and the underlying concepts.

Contextual Notes

Participants have not reached a consensus on the correct approach to drawing the diagrams, and there are indications of missing assumptions regarding the treatment of supports and loading conditions. The discussion also reflects uncertainty about the relationships between shear and moment diagrams.

togo
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Homework Statement


- Compute the reactions at the supports
- Draw complete shearing force and bending moment diagrams
- Determine magnitude and location of maximum absolute value of shearing force and bending moment
- Use free body diagram approach to determine internal shearing force and bending moment at any specified point in a beam
- Write equations for all segments of shearing force and bending moment diagrams

Homework Equations


M = FD


The Attempt at a Solution


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I didn't attempt to finish it since I sort of got stuck. I was looking for examples in the book for how to do this and can't seem to find. Am I even close to correct on either the shearing or bending diagram? thanks
 
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Your loading diagram shows two point loads, yet your shear diagram shows three discontinuities. Why?

Think this one through, and when you do, you should be on the way to a solution.
 
alright, so when you have a beam tacked onto a wall as in this example, is it treated the same way as though it was just sitting on a pivot on that end? thanks
 
oku3hf.jpg


an improvement I hope, still don't know how to approach the bending diagram of moments.
 
Your shear diagram shows a pair of steps, so there should be two different slopes evident on your bending moment diagram. I can't really tell if you tried to show that or not, but it is not very clear on your diagram. The left most slope should be quite a bit higher (magnitude) than the one of the right.

The built-in end does support a moment, unlike the pined end, and that is why the moment diagram does not go to zero on the left end. It comes out at the wall moment value.
 

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