Swedlers
The Schwedler girder is the ideal truss in bridge construction.
Since 1850/51 , Schwedler has been looking for optimal lines for the girders of truss bridges . In order to always only generate compressive forces in the uprights and tensile forces in the diagonals for every load position in the post framework (Fig. 1) , Schwedler must involve the belts in the transverse force transfer . Schwedler derived the belt curve from the condition that the diagonal force disappears (or is positive - that is, it is subjected to tension) for the most unfavorable load position; he had already investigated this problem theoretically in 1851. The upper chord should therefore have a saddle-shaped depression in the middle of the bridge (Fig. 2). However, this shape contradicts the static feeling. This is why the upper chord of the Weser Bridge at the Benedictine Abbey of Corvey near Höxter was laid parallel to the lower chord in the middle of the bridge (Fig. 3). With the 59.1 m wide-span Weser Bridge designed by construction inspector Simon, the first Schwedler girder was created, the top chord of which deviates slightly from the correct chord shape: "Schwedler did not specify the correct function for the chord guidance from the start".
Schwedler received a gold medal for the Weser Bridge at the Paris World Exhibition in July 1867.
Schwedler did not state the correct function until 1868 when planning the Dömitzer Elbe bridge, which was completed in 1873 (Fig. 4).
Web links
- Karl Gotsch: Swedish carrier
- Lexicon of all technology, edited by Otto Lueger, 2nd edition 1904–1920.
- K.-E. Kurrer: The structural innovations of Johann Wilhelm Schwedler (1823–1894)
proof
- ^ Karl-Eugen Kurrer in Stahlbau 85 (2016), volume 5.