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Author Topic:   A test of your common sense
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


(1)
Message 36 of 137 (665814)
06-18-2012 9:10 AM


Just to jump in here.
I'm a structural/stress engineer and deal with this kind of problem regularly.
For clarity (and correct me if I'm wrong here Taz)
The triangle at point A represents a "Simple Support" [edit: a simple support allows rotation but not translation] and the circle at point B represent a support that allows a horizontal translation and prevents vertical translation [edit: and allows rotation].
The material of the beam is irrelevant to answer the question. It will not slip through the supports as it is attached to them.
As the magnitude of the load is not specified, the question is fine as there will be "A" load at which the beam "fails"
as a hint, hold your pen at the edge of the table with your thumb holding the top of the pen down and the rest of the pen hanging over the edge (in kind of a "walk the plank" style).
Push down on the free end on the pen.
Now, assuming that you had enough downforce to resist, (i.e. simulate the fixity) the end of the pen at the table wouldn't move.
Where is this pen likely to break?
where will it experience the highest stress?
Edited by Heathen, : No reason given.
Edited by Heathen, : No reason given.

Replies to this message:
 Message 71 by RAZD, posted 06-19-2012 9:05 PM Heathen has replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 38 of 137 (665820)
06-18-2012 10:45 AM
Reply to: Message 33 by jar
06-17-2012 7:28 PM


the drawing is pretty clear,
but then again I'm familiar with that type of diagram.

This message is a reply to:
 Message 33 by jar, posted 06-17-2012 7:28 PM jar has replied

Replies to this message:
 Message 40 by jar, posted 06-18-2012 11:02 AM Heathen has replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


(2)
Message 39 of 137 (665821)
06-18-2012 10:50 AM
Reply to: Message 37 by Bolder-dash
06-18-2012 10:08 AM


Au Contraire...
He has perfectly shown how people with little or no knowledge of the subject at hand still feel they can wade in and point out what they see to be deficiencies in the diagram and therefore dismiss the question as nonsense.
When in fact to someone who knows the subject matter, the diagram is clear, consise and as has been shown in this thread, makes the point that Taz wanted to make quite well.
Edited by Heathen, : No reason given.

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Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


(2)
Message 41 of 137 (665826)
06-18-2012 11:13 AM
Reply to: Message 40 by jar
06-18-2012 11:02 AM


To me, he is pointing out how people with little knowledge of a particular subject, apply their own "Common Sense" and, simply because they do not understand the subject/problem/question, declare it a nonsense.
precisely what you have done.
As a structural engineer, that triangle, in that location, in that context, can mean only one thing.

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 Message 40 by jar, posted 06-18-2012 11:02 AM jar has replied

Replies to this message:
 Message 42 by jar, posted 06-18-2012 11:19 AM Heathen has replied
 Message 45 by ringo, posted 06-18-2012 12:12 PM Heathen has not replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


(2)
Message 43 of 137 (665829)
06-18-2012 11:30 AM
Reply to: Message 42 by jar
06-18-2012 11:19 AM


As a structural engineer, that triangle, in that location, in that context, can mean only one thing.
It's clear that it's a consequesnce of MS word or whatever he created the sketch in that the beam does not rest on the point of the triangle.
the meaning is clear.
I have seen worse sketches in calculation files for major civil airliners.
A sketch is just that, a sketch. when supported by numbers or the appropriate knowledge it's meaning is clear.
You said in message 33 that
The drawing is without meaning
Pretty close to declaring it a nonsense.
It does indeed REPRESENT an every day thing that most people deal with.
Everytime you cross a bridge, sit on a bench, walk up stairs, Put your coffee on the table, (I could go on... and on), you are dealing, directly, without knowing it with similar problems/situations to the one REPRESENTED in this diagram.

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 Message 42 by jar, posted 06-18-2012 11:19 AM jar has replied

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 Message 46 by jar, posted 06-18-2012 12:15 PM Heathen has replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 73 of 137 (665939)
06-20-2012 2:29 AM
Reply to: Message 46 by jar
06-18-2012 12:15 PM


And no, I do not deal with such things when I walk across a bridge.
You deal with the bridge when you cross it, a diagram as the one above REPRESENTS a bridge (or similar)
I'm not about to get into a semantics pissing contest with you regarding the meaning of "nonsense". You're on your own there.

This message is a reply to:
 Message 46 by jar, posted 06-18-2012 12:15 PM jar has replied

Replies to this message:
 Message 80 by jar, posted 06-20-2012 8:45 AM Heathen has replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 74 of 137 (665940)
06-20-2012 2:32 AM
Reply to: Message 71 by RAZD
06-19-2012 9:05 PM


Re: the technical "language" used ...
exactly.
And in a few cases in this thread responders have not attempted to learn the technical language and/or study the subject, but give their best guess based upon their "common Sense" or simply decide the problem is meaningless.
Taz's point proved.

This message is a reply to:
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Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 75 of 137 (665941)
06-20-2012 2:38 AM


here's a little Bending moment/Shearforce diagram calculator. should give some hints
http://www.glerok.com/sbd/

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 81 of 137 (665956)
06-20-2012 8:54 AM
Reply to: Message 80 by jar
06-20-2012 8:45 AM


The drawing is not without meaning.
You are without knowledge.

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Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 83 of 137 (665961)
06-20-2012 10:40 AM
Reply to: Message 82 by Tangle
06-20-2012 10:23 AM


Eh? Jar didn't ask the original question..
I think you've got some wires crossed...

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 Message 82 by Tangle, posted 06-20-2012 10:23 AM Tangle has replied

Replies to this message:
 Message 85 by Tangle, posted 06-20-2012 11:01 AM Heathen has replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 95 of 137 (666020)
06-21-2012 2:29 AM
Reply to: Message 85 by Tangle
06-20-2012 11:01 AM


..and again...

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 Message 85 by Tangle, posted 06-20-2012 11:01 AM Tangle has not replied

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 96 of 137 (666021)
06-21-2012 2:31 AM
Reply to: Message 94 by Taz
06-20-2012 5:57 PM


So put them out of their misery Taz!

This message is a reply to:
 Message 94 by Taz, posted 06-20-2012 5:57 PM Taz has replied

Replies to this message:
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Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 121 of 137 (666118)
06-22-2012 3:52 AM


Edit.. it's been answered.. and I can't be arsed.
Edited by Heathen, : No reason given.

  
Heathen
Member (Idle past 1283 days)
Posts: 1067
From: Brizzle
Joined: 09-20-2005


Message 125 of 137 (666125)
06-22-2012 5:42 AM
Reply to: Message 104 by Taz
06-21-2012 1:35 PM


The point of the wheels is to transfer the load to the ground.
so put the wheels directly under where the plant pot transfers its load to the dolly.
that is the simplest most straight forward load path. a straight line down.
otherwise you're introducing a moment into the cross members.
Edited by Heathen, : No reason given.

This message is a reply to:
 Message 104 by Taz, posted 06-21-2012 1:35 PM Taz has replied

Replies to this message:
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