Bending Moment for Simply Supported, Overhanging Beam with two Overhangs

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    Bending Moment
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Discussion Overview

The discussion revolves around determining the bending moment equation for a simply supported beam with two overhangs, specifically in scenarios involving point loads and uniformly distributed loads. Participants are exploring how to formulate the bending moment in terms of the position along the beam.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks to adapt a formula for a beam with a uniformly distributed load to a scenario with point loads at the ends of the overhangs, questioning how to incorporate additional terms for bending moments.
  • Another participant requests clarification on the specific formula being referenced and asks for visual aids to better understand the scenario.
  • A participant expresses the intention to derive the moment equation for a beam with two point loads, indicating a shift from the original uniformly distributed load scenario.
  • One contributor outlines their approach to summing moments about a shaft, proposing a formulation for the moment as a function of position, while expressing uncertainty about the correctness of their method due to a lack of recent experience in the subject.
  • A later reply notes that the beam is over-supported and suggests that this situation requires a different approach, referencing external material on statically indeterminate beams.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are multiple competing views on how to approach the problem, and uncertainty remains regarding the formulation of the bending moment equation.

Contextual Notes

Participants express varying assumptions about the loading conditions and the nature of the beam, indicating potential limitations in their approaches. The discussion includes references to external resources that may provide additional context or methods.

benwb93
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Homework Statement
Bending Moment for Simply Supported, Overhanging Beam with
Two overhangs
Relevant Equations
Bending Moment
1713737517466.png

This formula works for a beam with one uniformly distributed load... How would I apply the same technique to get the bending moment equation in terms of x for the same type of scenario with a point load before R1 and after R2 at each end of the overhangs? Would I simply add a term for each the positive and negative bending moment to the already provided R1x-w(a+x)^2/2 ?
 
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Welcome, @benwb93 !

What formula (which works for a beam with one uniformly distributed load) are you referring to?
Could you post an image with better quality for us to be able to see its details?
Could you also post a handmade diagram of the situation that you describe?
 
I am looking to solve the Mx moment equation in terms of x for the same scenario in the situation posted above, but with the uniform load replaced by two point loads at each end of the overhangs. This is what I am trying to formulate:
1713752943803.png

these two point loads are overhanging the same distance from each furthest bearing, instead of using the uniformly distributed load, I want to apply this formula to this situation with 2 point loads.

Formula above originated from here: https://www.linsgroup.com/MECHANICAL_DESIGN/Beam/beam_formula.htm
 
1713755873049.png

Essentially, I want the sum of moments about this shaft

My assumptions is it would be something like:

Summing moments at 0
M=-Fp(a)+R1(b)+R2(c)-R3(d)+Fg(e)

but instead I want to formulate it as a function of x where I can write it as shown in the formulas above, M(x)=R1x-w(a+x)^2/2

If I do this and sum up the moments this is what I get:
1713760563503.png

for some reason im not positive that this is correct as I havent done much CE/strengths of materials in awhile
try to ignore the smudges from my scanner and the random change into meters in the final solution

there would be another orthogonal set of planes with another moment reaction obviously but is this formulation correct as it stands so far?
 

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