Find Reactions to Overhanging Beam

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Discussion Overview

The discussion revolves around determining the reactions for an overhanging beam in static equilibrium. Participants explore the methods for calculating forces and torques, addressing both theoretical and practical aspects of the problem.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about finding all reactions and seeks assistance.
  • Another participant suggests that calculating forces involves ensuring both net force and torque are zero in equilibrium.
  • A participant questions whether a charnier needs to be added when selecting a point for torque calculations.
  • Clarification is provided that no additional elements are needed; any point can be chosen for torque calculations.
  • Participants discuss the moment equation and the process of isolating variables, with one participant providing a specific equation involving Dy.
  • Concerns are raised about the clarity of variable definitions and the need for explanations of terms used in the calculations.
  • One participant describes the distribution of forces along the beam and seeks to identify where a single force acts.
  • There is a discussion about finding the midpoint between two points on the beam, with participants attempting to calculate the average position of forces.
  • Confusion arises regarding the calculation of the average between two values, leading to further clarification attempts.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the calculations and interpretations of the forces and moments involved. Multiple viewpoints and methods are presented, leading to ongoing confusion and clarification attempts.

Contextual Notes

Some participants express uncertainty about variable definitions and the calculations involved, indicating potential gaps in understanding the problem setup and mathematical steps.

Ozkan Suna
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The question is:

How do I find all the reactions? I haven't worked with a similar problem before, so I'm kinda confused. Hope someone will help!

Thanks from now.
 
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Finding all forces should be easy from the sketch. To calculate their values: Both net force overall and torque around a point of your choice have to be zero in equilibrium.
 
'' Point of my choice has to be zero '' Does it mean I have to add a charnier? Sorry for the confusion
 
You don't have to add anything. Pick a random point. Calculate all torques around that point from all the forces. The sum has to be zero.
 
So if I want the moment ΣMz = 0; Dy * 6a - P*10a - p*5a*2,5a = 0
and then isolate Dy and substitute it in ΣFy = 0; By + Dy = 5ap + P??
 
If you introduce new variables, you should define them somewhere. An explanation what is what would be useful as well.
Ozkan Suna said:
P*10a
Why 10a?
Ozkan Suna said:
- p*5a*2,5a
","? And assuming you mean 2.5, why 2.5?
Ozkan Suna said:
and then isolate Dy and substitute it in ΣFy = 0; By + Dy = 5ap + P??
Sure.
 
1) We have a single force at the end of the beam. So I say the force multiplied with the total lenght.

2) From the left side of the beam to the half we have distributed load. So I want to find where the single force attacks, and that is on the half on the beam, right?

Sorry for my bad English!
 
Ozkan Suna said:
2) From the left side of the beam to the half we have distributed load. So I want to find where the single force attacks, and that is on the half on the beam, right?
What is the middle between "2a to the left" and "3a to the right"?
 
Oh, so we have to split it up to 2a/2 = a and 3a/2 = 1.5a?
 
  • #10
You can split it in two pieces, but simply finding the middle works as well. The middle is not 2.5 a to the right of the support.
 
  • #11
1.5 a right?
 
  • #12
No.

Draw it on a piece of paper if that helps. Or use signs: Where is the middle between -2 and +3?
 
  • #13
a?
 
  • #14
Stop guessing please. How do you calculate the average between two values?
 
  • #15
Not guessing, it's confusion.
The average of -2 and 3 is: -2 + 3 / 2 = 1/2
 

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