Concrete Continuous Girder Bridges

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	*National Information Service for Earthquake Engineering* *University of California, Berkeley*


	Leonhardt, Andrä and Partners have designed numerous continuous prestressed concrete bridges from moderate spans of 30 meters up to 185 meters. The latter, the Cologne Bridge, though not the longest span in existence, is a record in slenderness ratio (1:24 over the piers and 1:56 at midspan).



	H19. Overall view.

BRIDGE ACROSS THE RIVER ELZ
AT EMMENDINGEN
(1949)

One of the first prestressed concrete bridges in Germany, main span 30 meters.
Superstructure is a solid slab, girder depth 1.2 meters at piers and 0.58 meters at center of main span, corresponding to slenderness ratios of 1:25 and 1:52 respectively.

Design.

References:

Leonhardt, F.: Bridges, Deutsche Verlagsanstalt 1982, p. 152.

Mörsche, E.: Brücken aus Stahlbeton und Spannbeton, 6. Auflage, neu bearbeitet von F. Leonhardt (Bridges of Reinforced and Prestressed Concrete, 6th Edition by F. Leonhardt). Verlag Konrad Wittwer, Stuttgart 1958, pp 66-68.

BRIDGE ACROSS THE NECKAR CANAL AT HEILBRONN-BÖCKINGEN
(1950)



	H20. Overall view.


	One of the very first long span prestressed concrete girder bridges, looking like a frame bridge, but having a continuous beam with spans of 19-96-19 meters. Construction depth 3.9 meters at supports and 1.7 meters at midspan, corresponding to slenderness ratios of 1:25 and 1:56. Prestressed with concentrate cables of parallel strands and loop anchorages.

Design.

References:

Leonhardt, F., Stöhr, W. and Gass, H.: “Neckar-Kanal-Brücke Obere Badstrasse, Heilbronn (The ‘Obere Badstrasse’ Bridge across the Neckar Canal at Heilbronn),” Beton- und Stahlbetonbau 46 (1951), pp 265-270.

APPROACH TO THEODOR-HEUSS BRIDGE AT DÜSSELDORF
(1953-56)



		H21. View from underneath. The space underneath the bridges is used as a parking lot.


	Total length 330 meters, maximum span 34 meters, width 23.1 meters. Due to its many columns, nicknamed “The Millipede”. Superstructure two continuous prestressed concrete box girders, slab cantilevered outside and supported inside by cross girders. Elliptical columns with stone masonry cladding.

Preliminary design.

Ref: Schmitz, H.: “Die Betonhochstrasse ‘Der Tausenfüssler’ (The Concrete Elevated Highway, ‘The Millipede’).” In: Nordbrücke Düsseldorf (The North Bridge at Düsseldorf). Springer Verlag, Berlin, Heidelberg. 1958, pp 105-114.



		H22. Trunk with Y-shaped columns.


	H23. Branch with single columns.

BRIDGE ACROSS JAN-WELLEN-PLATZ
AT DÜSSELDORF
(1961-62)

Elevated street over a highly crowded area connecting shopping centers. In plan, the bridge is Y-shaped. Total length 536 meters, spans varying from 20 to 25 meters. Width of trunk 12.9 meters of branches 9.9 meters.
Superstructure solid slab of prestressed concrete only 1 meter deep. The trunk has a “double-bosomed” section, the branches a “single-bosomed”, which make the bridge appear even more slender, as the small depth can scarcely be seen.
Columns of steel in order to achieve maximum slenderness and maximum transparency underneath the bridge.

Tender design in collaboration.

References:

Beyer, E. and Thul, H.: Hochstrassen (Elevated Highways). Beton-Verlag GmbH. Düsseldorf, 1967, pp 12, 63, 204, 205.

Leonhardt, F.: Bridges. Deutsche Verlags-Anstalt, Stuttgart 1982, pp 135, 136.



	H24. Construction. Note the steel girders used for transport of formwork, personnel and material.


	H25. Completed bridge, overall view from the slopes of the valley.

AUTOBAHN BRIDGE ACROSS THE KOCHER VALLEY AT GEISLINGEN
(1971-78)

Total bridge length 1128 meters, consisting of two side spans of 81 meters and seven inner spans of 138 meters. Deck width 31 meters. Height above valley up to 182 meters.
The superstructure of prestressed concrete is continuous from one abutment to the other and consists of the spine box girder, width 8.6 meters, depth 6.5 meters, and the cantilever slab supported by struts.
Piers up to 176 meters high and founded in depths up to 50 meters with twin caissons. Construction of spine girder from the piers to both sides by free cantilevering, construction of slab-cantilevers in a second stage about three months later. Construction of piers with climbing formwork. During the preliminary and tender design phase, subsoil experts had judged the hill slopes inadequate for foundations. Therefore, tender design as cable-stayed bridge with main span of 624 meters and slide spans of 276 meters, with steel deck and concrete towers.

H26. Completed Bridge, details of superstructure and struts.

Preliminary and tender designs. Alternate design of Wayss and Freytag chosen for construction. Checking of the final design.

References:

Linse, A. and Wössner, K.: “Kochertalbrücke-Entwürfe einer Grossbrücke (Kocher Valley Bridge, Designs for a Large Bridge).” Bauingenieur 53 (1978), pp 453-463.

Baumann, H.: ““Kochertalbürcke Geislingen (Kocher Valley Bridge at Geislingen).” In: Spannbetonbau in der Bundesrepublik Deutschland 1978-1982). Deutscher Betonverein e. V., for FIB 9th Congress, Stockholm 1982, pp 62-66.

RHINE BRIDGE, COLOGNE-DEUTZ
(1976-80)

Widening and remodeling of the bridge in Slide H3, consisting of extension of piers, widening of the abutments, construction of a new twin bridge and remodeling of the existing bridge. Coupling of the new and old parts of the piers by drilled-in 150-ton prestressed tendons.
Twin bridge with spans and girder depth the same as existing bridge, designed as steel and prestressed concrete bridge. Competitive bidding proved the concrete alternate to be about 10% cheaper. Use of high strength B 55, and lightweight LB 45 concrete in the 67-meter long central portion of the main span. Construction by free symmetrical cantilevering on both sides of the piers, using stabilizing auxiliary piers.
Existing bridge remodeled by dismantling upstream walkway, shifting streetcar tracks, and placing asphalt layer.

Extension of piers:
Tender design and tender documents, final calculation and drawings.

Twin bridge:
Tender design and tender documents for steel and concrete alternate. Checking of final calculations and drawings.

Remodeling of existing bridge:
Tender design and tender documents, final calculations and drawings.

References:

Andrä, W. and Falkner, H.: “Die Nachkriegsgeschichte der Rheinbrücke Köln-Deutz (The Postwar History of the Rhine Bridge Cologne-Deutz).” Bauingenieur 54 (1979), pp 306, 307.

Stadt Köln, Amt für Brücken- und U-Bahnbau: “Rheinbrücken im Kölner Stadtbahnnetz (Rhine Bridges within the Rapid Transit System of Cologne),” Kölner Informationen, Oktober 1980, pp 10-28.

Knop, D. and Urban, J.: “Neue, frei vorgebaute Spannbetonbrücken über den Rhein in Köln-Deutz, Konstanz und Weil (New Prestressed Concrete Bridges across the Rhine, Built by Free Cantilevering, at Cologne-Deutz, Konstanz and Weil),” Beton- und Stahlbetonbau 1980, pp 153-160 and 197-200.

Zellner, W. and Saul, R.: “Über Erfahrungen beim Umbau and Sanieren von Brücken (On Experiences Gathered in the Remodeling and Restoration of Bridges).” To appear shortly in ‘Die Bautechnik’.


	H27. Cross-section with construction sequence. Left: pier has been extended and new bridge has been built. Cantilevers of old bridge are dismantled and new bridge is moved transversely on sliding bearings. Right: Final Stage.


	H28. Construction sequence of new bridge.


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	H29. New bridge taken from upstream.


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	The University of California, Berkeley Copyright 1997, The Regents of the University of California. Structural Engineering Slide Library, W. G. Godden, Editor Set H: Structures of Leonhardt, Andrä and Partners