Beam support conditions (Boundary Conditions) in practice

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Discussion Overview

The discussion revolves around the practical reproduction of support conditions for beams, specifically fixed and simply supported boundary conditions. Participants explore the challenges and methods associated with achieving these conditions in real-world applications.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that hammering an end of the beam into a wall represents a fixed boundary condition.
  • Another participant argues that achieving complete fixity is the most difficult and possibly impossible, while simply supported conditions are easier to implement.
  • A single pin connection is proposed as a method that does not significantly restrict rotation, potentially aligning with the criteria for a simply supported beam.
  • A participant provides a link to a website that explains boundary conditions and examples of devices that achieve them.
  • There is a clarification that a pinned connection does not qualify as simply supported, as it can provide two reactions (vertical and horizontal) but no moment.
  • A participant notes that typical wide flange steel beams are treated as simply supported when connected via a shear tab without welding the flanges to the vertical element.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and practical implementations of fixed and simply supported conditions, indicating that multiple competing views remain without consensus.

Contextual Notes

There are unresolved aspects regarding the definitions of fixed and pinned connections, as well as the practical implications of achieving these conditions in construction.

koolraj09
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Hi all.
Let's say I want to reproduce the support conditions for a beam. The easiest one I could think of is fixed end. Like I hammer an end of the beam into the wall. This represents fixed boundary condition. Likewise can anyone point out how to reproduce Simply supported end condition in practice??
thanks
 
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What do you think the answer is?

Fixity is the most difficult to achieve, not the easiest, and complete fixity impossible.

Simply supported is easy, on the other hand, which is why so many designs assume this condition.
 
A single pin connection would not restrict rotation to any significant degree in 2D analysis... which probably meets your criteria for a simply supported beam.
 
Hey thanks Vadar2012!
 
Please note that the pinned connection described by jehake is not simply supported.

A simple support can only provide a single vertical reaction.

A pin can provide two reactions, vertical and horizontal, but no moment.

Yes that's a good link vadar.
 
"hammer an end of the beam to a wall" does not give me enough information to determine if it is fixed or pinned...

Typical wide flange steel beams (I-beams) used in steel construction are treated as "simply supported" if the web is connected to the vertical element (e.x. column) via a shear tab and the flanges of the beams are NOT welded to the vertical element. Go ahead and image search for "shear tab" to see what I mean.
 

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