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Incrementally Launched Bridges
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      The following are examples of a few of the most important incrementally launched bridges, giving special attention to historic development:

 

BRIDGE ACROSS CARONÍ RIVER AT CIUDAD GUYANA/VENEZUELA
(1962-64)

H70.  The finished bridge.
  • The first launched concrete bridge and thus the ancestor of all incrementally launched bridges.  Two-lane highway bridge, width 10.0 meters, plus two 2.8-meter wide walkways on lower level.
  • Side spans 48 meters, main spans 96 meters, due to variation of water level up to 12 meters and maximum current 5 meters per second.  Depth of box girder 5.6 meters, corresponding to 1/17 of main span.
  • The superstructure was assembled from precast elements, each 9.2 meters in length, over its entire length of 500 meters, and centrically prestressed with concentrated tendons.
  • Bridge launched using auxiliary piers in the main spans.
  • In 1977-78, the bridge capacity was increased by an incrementally launched twin bridge.

Design and construction supervision.

References: 

Leonhardt, F. and Bauer, W.:  “El Puente Sobre el Rio Caroní entre Puerto Ordaz y San Felix en Venezuela (The Bridge across the Caroní  River from Puerto Ordaz to San Felix in Venezuela),”  Trends 31, (1964), pp 27-29.

Bauer, W.:  “Spannbetonbrücken ohne Lehrgerüst - das Taktschiebeverfahren (Prestressed Concrete Bridges without Scaffolding - the Incremental Launching Method),”  Baumaschine und Bautechnik 16 (1969), pp 108-110.

Grant, A.:  “Incremental Launching of Concrete Structures,” ACI Journal, August 1975, pp 395-402.

 

H71.  Overall view.

BRIDGE ACROSS LOISACH VALLEY, BAVARIA
(1970-72)
  • Autobahn bridge, total width 2 x 15.25 = 30.5 meters.
  • Eleven spans varying from 41 to 52 meters, total length 586 meters.  Girder depth 3.0 meters corresponding to 1/17 of the maximum span.  Curved in plan.

Complete structural design.

Ref:  Leonhardt, F.:  Bridges.  Deutsche Verlagsanstalt, Stuttgart 1982, pp 196, 197.

 

BRIDGE OVER RESTEL VALLEY, ITALY
(1972-73)
  • Road bridge, width 9.0 meters, spans 10 x 32 = 320 meters.
  • Bridge strongly curved in plan, R = 150 meters, corresponding to an angle of 122°.
  • Girder depth 2.5 meters, corresponding to a slenderness ratio of 1:13.

H72.  Launching of superstructure.

Design and construction consulting.

Ref:  Giovanni, B.:  “Un Impalcato estruso:  il Viadotto Val Restel (An Extraordinary Construction:  the Val Restel Bridge),”  Rivista Technica dell’Ance, L’Industria delle construzioni 32 (1972), pp 3-14.

 

BRIDGE ACROSS NECKAR VALLEY AT NECKARBURG
(1976-77)

H73.  First arch finished.  First superstructure being launched.
  • Six-lane autobahn bridge, total width 2 x 15.0 = 31.0 meters, height over valley up to 95 meters.
  • Side spans 30 meters, main span bridged by an arch with a span of 154 meters and a height of 50 meters.  Distance between columns over arch 33 meters.
  • Arches with double-cell box girders, width 6.5 meters, depth 3.0 meters.  Superstructure has box girders 2.3 meters in depth, and width varying from 5.1 to 7.1 meters.
  • Arches built by free cantilevering using an auxiliary stay cable system.  Superstructures incrementally launched over stayed arch.

Consultant to the contractor.

References: 

Wössner, K., Gebhardt, H., Schabel, R. and Wörner, H.:  “Die Talbrücke Rottweil-Neckarburg im Zuge der A 81, BAB Stuttgart-Westlicher Bodensee (The Valley Bridge Rottwell-Neckarburg, Part of the Autobahn A 81 from Stuttgart to the Western Part of Lake Constance),”  Beton- und Stahlbetonbau 74 (1979), pp 237-243 and 278-281.

“Arch Slipformer Shuns Ground Support to Cross Valley,”  Engineering News Record, June 1, 1978, pp 26, 27.

 

H74.  Layout of finished bridge (above), and construction (below).

H75.  Construction with auxiliary stay cable system.

BRIDGE ACROSS MAIN RIVER
AT MAINFLINGEN
(1977-78)
  • Six-lane autobahn bridge, total width 2 x 19.5 = 39.0 meters (two separate structures)
  • Spans of 74-133-74 meters, the main span being the longest thus far built with incremental launching.  Girder depth 3.0-4.8 meters, corresponding to 1/44-1/28 of main span.
  • During construction, the central span had to be kept completely free from any obstructions for the navigation on the Main River.  In spite of that, the incremental launching method was applied advantageously by launching the bridge from both sides and by using auxiliary stays on top of the superstructure.  The curved underside of the box girder was straightened during launching with temporary wedges.

Structural design and construction consulting.

Ref:  “Extended Span Cuts Bridge Cost in Half,”  Engineering News Record, Nov. 17, 1977, pp 39, 40.

 

H76.  Launching of superstructure, note the auxiliary pier.

BRIDGE ACROSS THE MAIN RIVER AT MARKTBREIT
(1978-82)
  • Autobahn bridge, total width 2 x 15.0 = 30.0 meters.
  • Eleven spans varying from 37 to 108 meters, total length 928 meters, construction depth 3.42 to 5.8 meters, corresponding to a slenderness ratio of 1:11 to 1:18.6.
  • Construction with auxiliary pier in the main span.

Complete structural design and construction engineering.

 

H77.  Overall view of the bridge during construction.

H78.  Detail of piers at ridge of hills.

BRIDGE ACROSS AICH VALLEY NEAR STUTTGART
(1981-83)
  • Four-lane highway bridge, crossing two valleys, total width 27 meters, maximum height over valley 50 meters.
  • Longest bridge thus far launched from one end, total length 1161 meters, spans between 51 and 84 meters.  Girder depth 3.50 meters, corresponding to 1/24 of maximum span.  Fixed point of finished bridge at the ridge between the valleys. 
  • Launching from one abutment, using cable-stayed auxiliary piers in the main spans.

(See also Slides H65-H68, which are of the Aichtal Bridge.)

Detailed design and construction consulting.

References: 

Prospectus “Aichtal-Brücke” of contractors.

“Long Launch Aichtal Bridge Stretches German Codes,”  New Civil Engineer International, October 1982, pp 32, 33.
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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
Movable Bridges Across Shipping Lanes

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