Old Iron Bridge 3

Posted by Julie M. Dant on Mon, 10/15/07 21:34
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Comments by Jan Bjorklund on Mon, 10/15/07 21:39

Another angle that captures the derelict nature of the bridge perfectly for me. One wonders why the bridge has not simply been torn down or at least have access restricted?


Comments by Julie M. Dant on Mon, 10/15/07 21:42

Another..


Comments by Julie M. Dant on Mon, 10/15/07 21:53

One last one...Some Salt and Pepper filter. Sorry, but I REALLY liked this old bridge. The foundation was sturdy, but I could shake the old iron railings the over beams..You don't have to yell at me for being reckless...my husband already did! ;0) or ;0(


Comments by Pietro Cecchi on Tue, 10/16/07 05:44

Follows a little documetation about old structures...:)

METAL FATIGUE
Remarks by Sir Benjamin Baker (reported in 1910)
(English civil engineer and the chief designer of the railway bridge over the Firth of Forth)


[p.191] "Many engineers ignore the fact that a bar of iron may be broken in two ways—by a single application of a heavy stress, or by the repeated application of a comparatively light stress. An athlete's muscles have often been likened to a bar of iron, but if 'fatigue' be in question, the simile is very wide of the truth. Intermittent action, the alternative pull and thrust of the rower, or of the laborer turning a winch, is what the muscle likes and the bar abhors. A long time ago Braithwaite correctly attributed the failure of girders, carrying a large brewery vat, to the vessel being sometimes full and sometimes empty, the repeated deflection, although imperceptibly slow and free from vibration, deteriorating the metal, until in the course of years it broke. These girders were of cast iron, but it was equally well known that wrought iron was similarly affected, for Nasmyth afterward called attention to the fact that the alternate strain in axles rendered them weak and brittle, and suggested annealing as a remedy, having found that an axle which would snap with one blow when worn, would bear eighteen blows when new or just after annealing. We know that the toughest wire can [p.192] be broken if bent backward and forward at a sharp angle; perhaps only to locomotive and marine engineers does it appear that the same result will follow in time even when the bending is so slight as to be unseen by the eye. A locomotive crank-axle bends but 1/34 inch, and a straight driving axle but 1/64, under the heaviest bending stresses to which they are exposed, and yet their life is limited. Experience proves that a very moderate stress alternating from tension to compression, if repeated about a hundred million times, will cause fracture as surely as bending to a sharp angle repeated a few hundred times."

From: Inventors at Work: With Chapters on Discovery, by George Iles, publ. Doubleday (1910) pages 191-192.

INTERESTING, ISN'T?



Comments by Caillault on Tue, 10/16/07 13:13

What Julie : no more black and white ? ? ?
(Very good, though !)


Comments by Linda Frey on Tue, 10/16/07 17:41

Good you got pictures. It doesn't look as though it will last much longer.


Comments by Maria Salvador on Wed, 10/17/07 14:47

:-)Agree with Linda!


Comments by Lilith on Sat, 11/03/07 17:09

I really love old subjects like this. You've used a great angle and depth.