Truss

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A truss frame is originally a supporting structure in the timber , wherein the on the carrier load end (bar) force by oblique struts taken under the support ( "blasted off on the support") is. The load on the structure is divided into vertical and horizontal forces, which must be absorbed by the abutments and the foundations of the struts. If only one point is supported by the struts, one speaks of a simple truss, if several points are supported, it is a double or multiple truss. The load-bearing capacity of the beam is increased by the inclined supports almost to the same extent as could be achieved by simple vertical supports that start at the same points.

Pont du Languedoc in Gignac , a two-span double truss (or "V-shaped inclined pile rigid frame") construction.

In bridge construction, the advantage of this construction method is that the cross-section of a river is not narrowed as much as by vertical supports. Except for wooden bridges, this type of structure is used today in steel and reinforced concrete bridge construction. The largest truss bridge is the Viadotto Sfalassà on the A3 Autostrada in Calabria .

  • Simple
    A-shaped truss

  • Double truss

  • No truss, double π-shaped rigid frame

In English, truss bridges are referred to as batter-post rigid-frame bridges , which in the free reverse translation means, for example, inclined pile rigid frame bridge. batter is derived in other meanings from beat (to beat, rubble, knock down), which is a bit closer to the term used in German. Also inclined-leg instead of batter-post is verifiable.

If the supports are anchored in the middle of the same foundation and strive in a V-shape to the roadway above, the shape (and for short) is called v-leg or v-shaped rigid-frame bridge . The simple truss would precede this with an A-leg or A-shaped . Unlike v- and A- , pi- shaped (π-shaped) rigid frame constructions do not use trusses.

Hanging truss

In contrast to trusses, the load of a hanging structure depends on the structure above. A combination of both systems are suspended trenches, through which larger spans can be achieved.

  • Simple hanging truss

  • Double hanging truss

literature

  • Theodor Krauth and Franz Sales Meyer (eds.): Das Zimmermannsbuch - Die Bau- und Kunstzimmerei with special consideration of the external form , original edition from 1895, Reprint Verlag Th. Schäfer, Hanover, 1981, ISBN 3-88746-004-9
  • Franz Stade: The wood structures - textbook for self-teaching , original edition from 1904, reprint Primus Verlag, 2013, ISBN 3-8262-3053-1
  • Karl-Eugen Kurrer : History of Structural Analysis. In search of balance , Ernst and Son, Berlin 2016, p. 34f, ISBN 978-3-433-03134-6 .

See also

Individual evidence

  1. ^ Gerhard Mehlhorn (Ed.): Handbook bridges . 2nd edition, Springer-Verlag, Berlin Heidelberg 2010, ISBN 978-3-642-04422-9 , pp. 282, 283
  2. ↑ Bridge Basics. Archived from the original on July 9, 2017 ; accessed on September 28, 2017 (English).