Lens wearer
The lens carrier is a carrier used in construction and has the outer shape of the side view of a double convex lens . It can often be found in girder bridges as a modification of a truss with straight and parallel belts . With him, both belts are convexly curved. Lens carriers are attached below or above the roadway. The latter is attached to the carrier with additional support elements because of the curvature of the straps.
In the literature, the fish-belly carrier , in which only the lower chord is convex, is sometimes referred to as a lens carrier.
history
A drawing by Leonardo da Vinci in his Codex Atlanticus is probably the oldest representation of a lens wearer. A century later, Fausto Veranzio showed a lenticular arched bridge in his Machinae Novae . Two centuries later, Claude-Henri Navier dealt theoretically with the properties of the lens wearer in 1826. The lens holder was probably developed for practical use by the leading architect of the Kingdom of Hanover Georg Ludwig Friedrich Laves at the beginning of the 19th century.
Lens wearer
Laves created a "fake" arch bridge by adding a lower arch to the upper arch and connecting the two at their ends: «While the lower chain [the lower arch] prevents the upper arch from giving way, the upper arch resists the contraction of the arch Chain [of the lower arch] , whereby both forces are neutralized and an existing whole is achieved, which neither pulls nor pushes, but acts or pushes perpendicularly on the points of the base. " The lenticular beam , also known as the Laves beam , made it possible to build longer than previously tensioned beam bridges (only vertical bearing forces). He patented this invention in 1835. He applied it to the Stadtgrabenbrücke in Hanover and to three bridges in Derneburg . It is a lattice girder with curved or polygonally shaped belts, usually arranged symmetrically to a horizontal axis, with the greatest height in the middle of the girder. The walings unite above the supports.
Pauli bearer
(replaced by fish belly girders in 1908/09)
The further development of the lens carrier was carried out by Friedrich August von Pauli , who used it on the first Großhesseloher Bridge in Munich, which was built between 1851 and 1857 . In the named after him, outwardly hardly from Lavesträger with parabolic belts (s. A. Parable carrier ) distinguishable Pauli carriers have upper and lower chords at all points the same voltage, they can therefore be carried out at all points with the same cross section. Heinrich Gottfried Gerber made the most important theoretical contribution to the calculation of Pauli's construction system in an article in 1865. From 1860 to 1862, Gerber built the largest Pauli girder bridge, the Mainz Rhine Bridge . From 1870 the system lost more and more importance, even if Gustav Lindenthal built the large Smithfield Street Bridge in Pittsburgh , PA according to this system from 1881 to 1883 .
The Großhesseloher Bridge may have influenced Isambard Kingdom Brunel in the construction of the Royal Albert Bridge , who was known to Laves since his visit to England.
literature
- Helmut Knocke : Laves-Balken In: Klaus Mlynek, Waldemar R. Röhrbein (eds.) U. a .: City Lexicon Hanover . From the beginning to the present. Schlütersche, Hannover 2009, ISBN 978-3-89993-662-9 , p. 389.
- Karl-Eugen Kurrer : German Steel Construction Day in Hanover , in: Stahlbau , 84th year (2015), no. 2, pp. 143–151.
Individual evidence
- ↑ Since the ends of the arches are not pointed, but rather in a circle like an ellipse , this shape is also known as an ellipse carrier.
- ↑ a b Otto Lueger (Ed.): Linsträger , Lexicon of the entire technology and its auxiliary sciences . Vol. 6, Stuttgart, Leipzig 1908, p. 171. On Zeno.org
- ↑ Dirk Bühler: The Großhesselohe railway bridge in ScienceBlogs of the Deutsches Museum with a representation of the development of the lens carrier
- ↑ Laves, quoted from: in VSVI-Information, magazine of the associations of road construction and traffic engineers in Lower Saxony and Bremen, issue No. 3, December 2009, page 14 ( Memento from December 29, 2009 in the Internet Archive )
- ^ Günther Kokkelink: Laves, Georg Ludwig Friedrich . In: New German Biography .
- ↑ On his trips to England he may have seen George Stephenson's Gaunless Bridge for the Stockton and Darlington Railway, which appears to be constructed similarly.
- ↑ Otto Lueger (Ed.): Paulischeträger , Lexicon of the entire technology and its auxiliary sciences . Vol. 6, Stuttgart, Leipzig 1909, pp. 54-56. On Zeno.org
- ^ Heinrich Gerber: The calculation of the bridge girders according to the Pauli system . In: Journal of the Association of German Engineers , ZDB -ID 200611-x , 1865.
- ↑ Engineer portrait in db-bauzeitung 6/02 ( Memento from December 29, 2013 in the Internet Archive )