Bridge Builder Buff? Traditional Cache

This cache has been archived.

La Lunatica: As there's been no cache to find for months, I'm archiving it to keep it from continually showing up in search lists, and to prevent it from blocking other cache placements. If you wish to repair/replace the cache sometime in the future, just contact us (by email), and assuming it meets the guidelines, we'll be happy to unarchive it.

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Hidden : 8/21/2010
Difficulty:
3 out of 5
Terrain:
2.5 out of 5

Size: Size: micro (micro)

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Geocache Description:

I found this lovely peaceful spot whilst doing some research for an extreme series I'm planning. I sat here for a while just enjoying the scenery and watching the fish....it just had to have a cache. I decided to do a little research on the bridge design & Builder, just for interest, and was amazed to find out that it was a distant relative of a local cacher

Plate Girder Bridge

Plate Girder Bridge
A '''plate girder bridge''' is a bridge supported by two or more '''plate girders'''. The plate girders are typically I-beams made up from separate structural steel plates (rather than rolled as a single cross-section), which are welding|welded or, in older bridges, bolted joint|bolted or riveted together to form the vertical web and horizontal flanges of the Beam (structure)|beam. In some cases, the plate girders may be formed in a Z-shape rather than I-shape. The first tubular wrought iron plate girder bridge was built in 1846-47 by James Millholland-Buff for the Baltimore and Ohio Railroad.

Plate girder bridges are suitable for short to medium spans and may support railroads, highways or other traffic. Plate girders are usually prefabricated, and the length limit is frequently set by the mode of transportation used to move the girder from the bridge shop to the bridge site.

Generally, the depth of the girder is no less than 1/15 the span, and for a given load bearing capacity, a depth of around 1/12 the span minimizes the weight of the girder. Stresses on the flanges near the center of the span are greater than near the end of the span, so the top and bottom flange plates are frequently reinforced in the middle portion of the span. Vertical stiffeners prevent the web plate from buckling under shear stresses. These are typically uniformly spaced along the girder with additional stiffeners over the supports and wherever the bridge supports concentrated loads.

Deck-type plate girder bridge
In the deck-type bridge, a wood, steel or reinforced concrete bridge deck is supported on top of two or more plate girders, and may act composite material|compositely with them. In the case of railroad bridges, the railroad ties themselves may form the bridge deck, or the deck may support Track ballast|ballast on which the track is laid. Additional beams may span across between the main girders, for example in the form of bridge known as '''ladder-deck''' construction. Also, further elements may be attached to provide cross-bracing and prevent the girders from buckling.

U-Type Plate Girder

Half-through plate girder bridge
In the half-through bridge, the bridge deck is supported between two plate girders, often on top of the bottom flange. The overall bridge then has a 'U'-shape in cross section (geometry)|cross-section. As cross-bracing cannot normally be added, vertical stiffeners on the girders are normally used to prevent buckling (technically described as 'U-frame behaviour'). This form of bridge is most often used on railroads as the construction depth (distance between the underside of the vehicle, and the underside of the bridge) is much less. This allows obstacles to be cleared with less change in height.

Multi Span Plate Girder Bridge

Multi-span plate girder bridge
Multispan plate-girder bridges may be an economical way to span gaps longer than can be spanned by a single girder. Pier (architecture)|Piers serve as intermediate abutments between the end Abutments of bridge. Separate plate girder bridges span between each pair of abutments in order to allow for expansion joints between the spans. Concrete is commonly used for low piers, while steel trestle work may be used for high bridges.

Additional Hints (Decrypt)

Hayhpxl sbe fbzr.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)


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