Suspension bracket
red = hinges,
blue = strap supplement parts which are slidably articulated to the suspended beam (marked with a cross)
A suspension girder (formerly also suspension girder ) in bridge construction is the part of a cantilever bridge that is hinged between two other bridge girders that protrude at one of their ends over the bridge pillar . The two supports which receive the load of the Einhängeträgers are to a boom or a cantilever beams - a cantilever - extended. It also happens that the suspension beam rests on a cantilever beam only at one end and on a pillar or an abutment at the other end .
The bridge is by inserting a Einhängeträgers to a statically determined Gerber beam bridge, which easily can be calculated as a statically indeterminate continuous beam . In addition, the suspension bracket together with the cantilevers leads to a larger span of the i. d. Middle part of the bridge. With conventional construction, an elongated central beam would be required, which would have a larger cross-section due to the higher stresses and would be heavier.
In the practice of bridge construction, a bridge girder lengthened with a cantilever girder is often referred to as a cantilever girder and the suspension girder as a tannery girder .
use
Prestressed concrete bridge with a large number of suspension girders
In the most common bridges with two piers, a suspension girder is usually arranged in the middle field , where it is supported by the cantilever girders protruding into the middle field .
There are also examples with two suspension brackets in the side panels (see the second illustration).
At the Viaur Viaduct , the two arched sections of the three-hinged arch bridge each have a cantilever towards the outside of the abutments. There is a short suspension bracket between these and the abutments.
Suspension girders were mainly used in the form of half-timbered girders in steel railway bridges at the beginning of the 20th century. The Forth Bridge and the Québec Bridge are the most famous examples from the time when there were no cheaper reinforced concrete bridges with large spans.
A reinforced concrete bridge with a multitude of suspension girders is the General Rafael Urdaneta Bridge over Lake Maracaibo in Venezuela . They are articulated on the ends of bridge girders, which are designed as wide pillar tables . This type of construction was later used in Italy, especially for long motorway viaducts .
construction
During construction, the suspension girders are usually delivered on a barge on the water ( floating in a bridge ) and lifted into their final position with winches attached to the cantilever girders . Occasionally, however, as with the Forth Bridge , they are also created with blocked joints in the cantilever arch.
Individual evidence
- ↑ Cantilever bridges. In: Otto Lueger (Hrsg.): Lexicon of the entire technology and its auxiliary sciences, vol. 1, Stuttgart, Leipzig 1904, p. 403. On Zeno.org
- ↑ Since the suspension beam has no direct support from pillars, it is also - not quite correctly - referred to as a floating beam . The English term suspended span is a little more precise.