Subject:
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Re: My newest creation, Hell Gate Bridge NY
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Newsgroups:
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lugnet.trains
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Date:
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Fri, 8 Dec 2000 11:57:21 GMT
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Viewed:
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982 times
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I'm not a civil, thanks for refining my critique.
In lugnet.trains, Scott Arthur writes:
> In lugnet.trains, Larry Pieniazek writes:
> >
> > Well, no, I'd have to categorise it as a type of through truss.
>
> I was going to leave this, but now that you started...
>
> I agree that is not a arch, and I expect that is was modelled on a truss.
> However, I'd call it a frame as it is pin jointed (trusses, I think are
> not). However, to be a frame all the members have to be in _pure_ tension or
> compression (ie no bending moments). This is not the case with James’s
> bridge. Additionally, the frame is statically indeterminate as it is not
> "perfect". To be a perfect frame:
>
> m=2j-3
>
> m=the number of members
> j=number of joints
>
> If it were a real structure, I’d expect it to have considerable movement.
>
> Basically, the problem is, it is not constructed from triangles. Despite
> that, it is fit for its intended purpose, and it does look very good.
Oh, indeed, it looks nifty. It's just not an arch. I'm not competent to
comment on whether trusses can't be pinned, though.
While we are identifying arches, though, I thought Ben "April Fool" Beneke
did one, no? I can't find it at the mo.
There are others out there, I think.
> {1} Durka – almost schoolboy level SE
> http://www.amazon.com/exec/obidos/ASIN/0582251990/qid=976273366/sr=1-5/106-5958974-3391625
Thanks for the ref.. out of print, though. What I'd like to have is
something more like a "bridge spotter's guide" with examples of all the
different interesting types and discussion of when you'd see them in use,
rather than a tome on how to analyse them... Following some refs got me to
textbooks that cost 250 USD and up!!!
++Lar
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Message has 1 Reply:
 | | Re: My newest creation, Hell Gate Bridge NY
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| (...) If we are talking bridge spotting, I'll be crossing this (road) one today: (URL) I cross it, I'll be looking at this (rail) one: (URL) picture: (URL) are about 8 miles from my office. Scott A (...) (24 years ago, 8-Dec-00, to lugnet.trains)
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Message is in Reply To:
| | Re: My newest creation, Hell Gate Bridge NY
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| (...) I was going to leave this, but now that you started... I agree that is not a arch, and I expect that is was modelled on a truss. However, I'd call it a frame as it is pin jointed (trusses, I think are not). However, to be a frame all the (...) (24 years ago, 8-Dec-00, to lugnet.trains)
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