Distributed load with overhang and multiple supports

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Discussion Overview

The discussion revolves around analyzing a structure supported by three or more supports that carries an evenly distributed load with overhang. Participants explore methods for calculating support reactions and deflections, particularly focusing on the center support's behavior as the outside supports are adjusted.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes using superposition to analyze the structure but is encountering unexpectedly low and potentially negative reactions at the center support as the outside supports are moved outward.
  • Another participant suggests that the center support reaction may become negative with the overhang but should trend towards positive as the outside supports are moved outward, indicating that the superposition method should work if calculations are correct.
  • A participant expresses confusion about their results, suspecting that their sign convention may be incorrect and plans to provide their work for further review.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the calculations or the behavior of the center support. There are competing views on the expected reactions and the effectiveness of the superposition method.

Contextual Notes

There are limitations related to the lack of shared calculations and diagrams, which may affect the clarity of the discussion. The discussion also depends on the definitions and conventions used by the participants.

gmreit
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I have a structure that can have 3 or more supports. It will carry an evenly distributed load with overhang. I thought I would tackle 3 supports first and solve with superposition but am getting the center support reaction to be very low and will go negative as I move the outside supports more outboard. I calculated the center deflection without the center support first then set that equal to the center deflection with the center support being the only point load. Then took those results back to the original FBD to find the outside support. What am I doing wrong?
 
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Hard to say what you are doing wrong without showing your work. With the overhang on each end the center support may likely be negative acting down on the beam, but it should be getting less negative and ultimately positive when you move the outside supports outward reducing the overhang. Your superposition method with deflection analysis should work if you are calculating deflections correctly or using tables properly.
 
Thanks for the reply. I seem to be getting the opposite responce as I move the outside supports outward. I will take a picture of my work then for you to check. I wonder if my sign convention is off somewhere
 
gmreit said:
Thanks for the reply. I seem to be getting the opposite responce as I move the outside supports outward. I will take a picture of my work then for you to check. I wonder if my sign convention is off somewhere
This is a homework-like question. Please start a new thread in the homework forum, and make sure you fill out the homework template.

Thread closed.
 

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