Fish belly bearer
The fish belly beam is a beam used in construction with the outer shape of a fish belly. It can often be found in girder bridges as a modification of a truss with straight and parallel belts . Its straight upper chord is retained, while the lower chord is convexly curved. Fish-bellied girders are arranged under the roadway, because the straight top flange is predestined to accommodate the usually straight roadway.
In the literature, the lens wearer , whose two belts are convex, is sometimes referred to as a fish-belly wearer.
History, function and application
The predecessor of the fish belly carrier is the lens carrier .
Not long after it was applied, the opinion prevailed that the straight track beam was sufficient to absorb the compressive forces and that the upper arch could therefore be dispensed with. This resulted in the fish-belly girder lying under the roadway .
The shape of the underside of the fish-belly girder is preferably parabolic, which corresponds to the course of the bending moment in it at constant line load. The distribution of forces can be read directly from the shape. That is why both experts and laypeople find this shape harmonious, elegant and aesthetic, especially when a bridge is built with a large number of such girders one behind the other.
A bridge made of fish belly girders is called a fish belly bridge. Most fish-bellied bridges were built in iron or steel construction during the construction of railway lines, and more rarely in road construction. Fish-bellied bridges in prestressed concrete construction, however, are extremely rare. Fish -bellied girders were occasionally used in solid wall girders (old cast-iron bar girders or sheet metal girders ) as a form for girders of the same strength. This type of construction has become unusual today. They are mainly found on railway bridges from the 19th century and up to the 30s of the 20th century, or in industrial construction.
Well-known, still existing fish belly bridges are the bridges of the Wutachtalbahn (Biesenbach Viaduct, Wutachviadukt, Fützen valley crossing) and the bridge of the Wuppertal Railway over the Beyenburger reservoir in Wuppertal - Beyenburg . Others are the Sitter Viaduct of the Südostbahn (SOB) in the Swiss canton of St. Gallen and the Lengenfeld Viaduct in Thuringia .
Individual evidence
- ↑ a b Fischbauchträger Otto Lueger (Ed.): Lexicon of the entire technology and its auxiliary sciences , Vol. 4, Stuttgart, Leipzig 1906, p. 41.
