Gmündertobel Bridge
Coordinates: 47 ° 23 '16 " N , 9 ° 20' 53" E ; CH1903: 744,161 / 250,304
| Gmündertobel Bridge | ||
|---|---|---|
 |
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| use | Road bridge 463 | |
| Crossing of | Sitter | |
| place | Stein AR - Teufen AR | |
| construction | Reinforced concrete - arch bridge | |
| overall length | 173 m | |
| width | 10.50 m | |
| Clear width | 79 m | |
| Arrow height | 26.50 m | |
| height | 70 m | |
| start of building | 1907 | |
| completion | 1908 | |
| planner | Emil Mörsch , A. Sutter | |
| location | ||
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The Gmündertobel Bridge in the Swiss canton of Appenzell Ausserrhoden leads the Steinerstrasse (Hauptstrasse 463) between the villages of Stein and Teufen over the deeply cut Sitter Gorge .
The bridge is located a few kilometers south of the city of St. Gallen , but is not part of the St. Galler Brückenweg as it is on the other side of the canton border .
The Gmündertobel Bridge is an important example of early concrete arch bridges. When it was completed in 1908, it had the world's largest concrete arch for a short time.
description
The Gmündertobel Bridge spans the Sitter with a large concrete arch with a clear width of 79 m , to which two round arches adjoin on the eastern side and four on the western side with spans of 10.25 m each. The bridge's lane, which is elevated on the arch, is around 70 m above the bed of the sitters. Originally the bridge had a 5.70 m wide carriageway and two 0.60 m wide walkways, i.e. a width of 6.90 m between the concrete parapets. During renovations in 1960 and 1961, the deck slab was renewed and widened to a total of 10.50 m
history
In the 1530s, a wooden crossing over the Sitter in the area of today's bridge was first mentioned. In 1710 a covered wooden bridge was built. It was raised after a flood in 1783; on the occasion, their roof structure was also raised so that riders no longer had to dismount. In 1856 it was replaced by a wrought-iron lattice girder bridge on high cast-iron pillars, which crossed the gorge at a height of about 55 m. It became dilapidated around 1900. Since there was enough gravel and sand in the valley of the Sitter, it was decided to build a concrete bridge, which could be built about 100 m downstream of the old iron bridge at a point where it almost connected to the altitude of the surroundings.
The design of the bridge was made by the young ETH professor Emil Mörsch , assisted by the Ausserrhoder cantonal engineer Andreas D. Sutter, who also took over the construction management. Construction began in March 1907 and was completed on November 7, 1908 when the bridge was handed over to the canton. The construction costs were, among other things, due to the sharp rise in wage and material costs, well above the offer price, which meant a loss of 25,000 francs for the construction company and a little later meant bankruptcy. The access roads were built considerably late, so that the bridge could not be opened to traffic until November 22, 1909.
Fundamental renovations were carried out in 1960 and 1961, combined with a widening of the carriageway slab, and in the years 2011 to 2013, during which, among other things, the carriageway slab was again reinforced in accordance with the requirements that have since increased.
Technical details
Mörsch added two three-hinged arches with spans of 70 m to the Grünwalder Isar Bridge, which was completed in 1904, which was then the largest concrete arch in the world.
For the Gmündertobel Bridge, he designed a significantly larger, clamped, elastic arch without joints at 79 m, which had to be based on the Swiss reinforced concrete standard of 1906 with its still very cautious approaches to permissible tensions, which Mörsch according to his theory of elasticity or the method calculated which he had presented in an article published in 1906.
Today, the Gmündertobel Bridge is considered an outstanding example of integral concrete bridges, in which structural parts were connected to form monolithic structures that are characterized by holistic load-bearing behavior, economical production and high aesthetics.
The arch has an arrow height of 26.5 m. It is 6.50 m wide at the top and 7.50 m wide at the fighters . The arch thickness increases from 1.20 m at the top to 2.13 m at the fighters. A reinforcement of the arch was theoretically not necessary, but to be on the safe side, some reinforcing iron was inserted into the upper and lower vault reveals.
The arch rests on abutments that are concreted deep into the slopes about halfway up the gorge and at the same time form the foundation for the large pillars on both sides of the arch.
On both halves of the arch there are 6 rows, each with four supports, which carry the deck slab, with the positions of the supports corresponding to the longitudinal girders under the deck. The inner pillars have a square cross-section of 0.50 m × 0.50 m, the outer pillars, on the other hand, have a T-shaped cross-section for architectural reasons, which gives them a wider visible area of 0.80 cm. In addition, follow the outer supports the tightening of the end face of the large arc. All supports are firmly connected to both the arch and the deck.
The carriageway slab is divided into sections 49.3 m long above the western side openings, 81.8 m above the main arch and 25.5 m above the two eastern side openings, which were originally connected to one another by sheet metal plates and today by expansion joints. The middle section does not rest on the large pillars. Rather, Mörsch had a 0.25 m thick and 12 m high reinforced concrete wall inserted into recesses in the uppermost area of the pillars on both sides, which is firmly connected to the deck. This reinforced concrete wall is elastic enough to follow the linear expansion of the 81.8 m long carriageway slab (1 cm on both sides was necessary, 2 cm is possible). A gap of 12 cm was provided for the formwork between the wall and the pillar, but this was enlarged to 20 cm during construction to make the work easier.
The roadway rises slightly above the main arch towards the apex of the arch in order to achieve a more pleasing appearance and to allow the rainwater to drain away more easily. The entire bridge was originally covered with a jute asphalt cover as protection against the ingress of water. When the deck was renewed, the sealing was also renewed and the original concrete parapet was replaced by a steel railing.
For the construction of the bridge arch, Richard Coray created a falsework that stood on specially made concrete foundations on the valley floor and on the side slopes. 1.5 m³ of wood had to be used for 1 m³ of arched concrete. However, the wooden beams could then be used again for another Sitter Viaduct.
Before starting the concreting work, detailed tests were carried out on the best mixing ratios for sand and gravel. As in the case of the Kempten Illerbrücken bridges , it was found that certain types of sand unwashed, i.e. with the finest parts, resulted in greater compressive strength, as well as when the stone dust produced when the stones were broken was not washed out. Therefore unwashed fine pit sand as well as washed coarse river sand and river gravel as well as unwashed limestone gravel with a grain size of 1-25 mm were used. A material ropeway was used to transport gravel and sand out of the river bed, and the concrete was brought to the installation site with a cable crane .
Web links
Individual evidence
- ↑ a b c Thomas Fuchs: Gmündertobel Bridge near Teufen: a pioneering work from 1908. In: Appenzeller Calendar , Volume 291 (2012), doi : 10.5169 / seals-515310
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↑ a b A. Sutter: The Gmünder Tobel Bridge near Teufen (Appenzell), Switzerland. In: Deutsche Bauzeitung, XLII. Vintage,
N °. 90 of November 7, 1908, pp. 613 (photo), 614; N ° 93 of November 18, 1908, p. 637 (photo), 638 (continued from N °. 90); N °. 95 of November 25, 1908, p. 649 ( digital version PDF; 32.7 MB),
N ° 97 of December 2, 1908, p. 666 (photos); N °. 98 of December 5, 1908, p. 669 (conclusion from N ° 95) ( digitized PDF; 33.4 MB, each on opus4.kobv) -
^ A b c d e f g Emil Mörsch: The Gmündertobel bridge near Teufen in the canton of Appenzell. In: Schweizerische Bauzeitung , Volume 53,
Issue 7 of February 13, 1909, p. 81, doi : 10.5169 / seals-28096 ,
Issue 9 of February 27, 1909, p. 114, doi : 10.5169 / seals-28106 ,
issue 10 from March 6, 1909, p. 122, doi : 10.5169 / seals-28109 - ↑ a b Green light for the renovation of the historically valuable Gmündertobel Bridge. Media release of July 9, 2010 by the Cantonal Administration AR
- ↑ The repair of the Gmündertobel Bridge has been completed. Article from September 30, 2013 in St.Galler Nachrichten
- ^ Christian Menn: Reinforced concrete bridge construction over the past 50 years. In: IABSE reports of the working commissions = Rapports des commissions de travail AIPC = IVBH reports of the working commissions, Volume 032 (1979): IABSE Symposium (Zurich): Bridges. Symposium report ( digitized 1.9 MB, on ETH - e-periodica)
- ^ Emil Mörsch: Calculation of clamped vaults. In: Schweizerische Bauzeitung, Volume 47, Issue 7, of February 17, 1906, pp. 83-85, doi : 10.5169 / seals-26057 and Issue 8 of February 24, 1906, pp. 89-91, doi : 10.5169 / seals -26058
- ^ Gerhard Mehlhorn, Manfred Curbach (Ed.): Handbook bridges . 3rd edition, Springer-Vieweg, Wiesbaden 2014, ISBN 978-3-658-03339-2 , p. 104 ( limited preview on Google Books)