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Structural Engineer's Eye Candy

Structural Engineer's Eye Candy

Structural Engineer's Eye Candy

(OP)
You can visualize the load path.  Very nice old bridge.

 

RE: Structural Engineer's Eye Candy

The riveters got pretty good at it after a while!

RE: Structural Engineer's Eye Candy

JAE, where is that? It's lovely!

RE: Structural Engineer's Eye Candy

(OP)
The title says:  Circa 1908. "Arch bridge, Bellows Falls, Vermont."

This photo is from www.shorpy.com

 

RE: Structural Engineer's Eye Candy

Nice one, JAE.  The wikipedia article which Mike referenced says that it was a three-hinged arch, but I can't see a hinge at the top.

RE: Structural Engineer's Eye Candy

hokie66 - looks like Wikipedia needs a correction on that!

It says that this type of structure was used in Europe at that time.  I can't think of any European arches of that type from as early as 1908.

Any suggestions?

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
 

RE: Structural Engineer's Eye Candy

This one in 1916 in the US, then the Tyne bridge, Bayonne Bridge and Sydney Harbour Bridge in early thirties.  1908?  I don't know.

RE: Structural Engineer's Eye Candy

Guys, zoom in the the sign at the right portal; pretty hefty fine for back then!

RE: Structural Engineer's Eye Candy

hokie,

The Wikipedia article goes on to say:  "As a departure from a normal three-hinged arch, the design incorporates a compression joint in each arch instead of the third hinge. He apparently did this to provide a continuous visual curve through the arches."

BA

RE: Structural Engineer's Eye Candy

About the OP, does anyone else here feel that there seems to lack sufficient lateral stiffness of the deck?

Tacoma narrows anyone...

tg

RE: Structural Engineer's Eye Candy

(OP)
hokie66,
I liked the Maria Pia Bridge.  Very nice "feel" to it.

All of these bridges seem to give me a sense that the lateral resistance to wind (per trainguy's comment) sort of makes you wonder how the calculations would come out with today's wind provisions.

Perhaps the bridges, despite their "airy" look, had enough mass to simply counteract any Tacoma Narrows effects.

 

RE: Structural Engineer's Eye Candy

If you go on to read the Wiki article, the BF Arch Bridge did indeed suffer a near failure at the hands of lateral loading by ice in the flood of '36. Although that may have been an issue with the abutments.  

RE: Structural Engineer's Eye Candy

BA,
I did read that, but would have to see the detail to be convinced that he had a real hinge.  Perhaps he just assumed a hinge to make the analysis easier.

RE: Structural Engineer's Eye Candy

Apologies to the author of the Wikipedia article.  If you zoom in on the crown in the photo in the OP (which is amazingly high resolution) you can see there is indeed a special detail at the crown, which is shown more clearly in photograph 14 from the set here:

http://bridgehunter.com/vt/windham/bellows-falls/

The demolition of this beautiful and historic structure seems yet another example of the way in which the products of engineers are seen as less important than those of architects.

I wonder if the original design calculations and drawings are filed away somewhere.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
 

RE: Structural Engineer's Eye Candy

Thanks, Doug.  Looks like he had that hinge all thought out, but without a compressive force in the four chords at the hinge, I think that would have compromised the lateral bracing.

RE: Structural Engineer's Eye Candy

hokie,

The lateral bracing at the hinge is not connected to the bottom chord.  It is connected to the top chord and a vertical member half way between top and bottom chords, so how is the lateral bracing compromised?

BA

RE: Structural Engineer's Eye Candy

BA,
The brace you are describing is the transverse sway brace.  The lateral bracing truss, tension only diagonals, is all in the plane of the top chord, and I thought the top chord was discontinuous at the joint, but the latest view which Doug attached shows a gusset there, so the "hinge" is just a half height connection.

RE: Structural Engineer's Eye Candy

So then...  could we all say that this is a 2.5 hinge arch and call it good?

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Structural Engineer's Eye Candy

I had the privilege a few short years ago to work on a train bridge demo/implosion job for a bridge built in the 1880's.
The bridge had a badly damaged portal frame at one end. We had to run some analysis for the demo guys.
Anyway....
You might be surprised by this...there was a total of 3 drawings for the bridge and, here is the kicker, the design calculations were included on one of the drawings.
Bridge stood, in service, for 100 years.
 

RE: Structural Engineer's Eye Candy

Toad - I'm not surprised. I've worked on the rehab and replacement of quite a few bridges overe railroads. They were mostly trusses in the 100 to 200 foot range. I don't think I ever saw a set of plans with more than five sheets. Oddly enough, we were able to get the shop drawings from ConRail, butthat was back in the 70's and 80's.  I tried without success a few years back. I guess with all the changing of hands with the railroad ownership the plans were all thrown out.

In NYC  back in the late 19th/early 20th C. the railroads were responsible for constructing vehicular bridges if their trackage was to be installed on a city street.  

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