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National Information Service for Earthquake Engineering
University of California, Berkeley
Incrementally Launched Bridges

GENERAL

      Since the construction of the Caroni River Bridge at Ciudad Guyana/Venezuela in 1964, more than 200 bridges have been built by incremental launching all over the world, and more than 75 of them have been designed by Leonhardt, Andrä and Partners.

      The basic idea of the incremental launching method is to prefabricate approximately 15- to 30-meter long units of the bridge under factory conditions behind an abutment and to launch the increasing bridge by sliding it on Teflon bearings into the final position without the aid of scaffolding.

      Incrementally launched bridges grant the owners lower first cost (due to reduced equipment and smaller work crews) and lower maintenance cost (due to additional prestress for launching) than any other segmental concrete bridge construction method.

      The procedure is illustrated by photographs of the Aichtal Bridge (Slides H65-H68) which is further featured in Slides H75-H76.

 

H64.  Schematic representation of incremental launching method.

      The main equipment for the construction of bridges by incremental launching is shown the following slides:

H65.  Stationary Formwork and Fabrication. 
The bridge superstructure is manufactured in stationary formwork in lengths corresponding to one-third to one-half of the normal span length.
According to climatic conditions, the fabrication plant may be covered by a tent.  Construction of one unit, hardening of concrete and subsequent launching require one week.

H66.  Launching Nose.
In order to reduce cantilever moments in the concrete girder during launching, a stiffened steel plate girder is fixed to the tip of the bridge, its length being normally 60% of the regular span length.

H67.  Auxiliary Piers.
For spans exceeding 15 times the girder depth, auxiliary piers are required  in order to reduce superstructure bending moments during launching.  The columns of the piers are of concrete in order to reduce deformations when being loaded.

H68.  Sliding Bearings.
The sliding bearings consist of concrete blocks covered with stainless steel and Teflon-coated reinforced elastomeric pads.

H69.  Launching Equipment.
The launching equipment consists of a combination of hydraulic jacks acting vertically and horizontally, and of sliding bearings.

      Depending on the degree of mechanization of the formwork, the cost of this special equipment is in the range of only $100,000 - $200,000 (in 1983).

References:

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

Bauer, W.:  “Auswirkungen des Taktschiebeverfahrens auf den Entwurf langer Brücken (Effect of the Incremental Launching Method on the Design of Long Bridges),”  Preliminary Report to the IABSE 9th Congress, May 1972, Amsterdam, pp 559-566.

Bauer, W.:  “Bridge Erection by Launching is Fast, Safe, and Efficient,”  Civil Engineering - ASCE, Vol. 47, No. 3, March 1977, pp 60-63.

Zellner, W., and Svesson, H.:  “Launching Step-by-Step,”  Consulting Engineer, July 1981, pp 14-16.

Göhler, B.:  “Entwicklungen im Taktschiebeverfahren (new Developments for Incremental Launching),”  Spannbetonbau in der Bundesrepublik Deutschland, 1978-1979.  Deutcher Betonverein e.V., for FIP 9th Congress, Stockholm 1982, pp 7-15.

Zellner, W., and Svensson, H.:  “Incremental Launching of Structures,”  ASCE Journal of Structural Engineering, Vol. 109, No.2, February 1983, pp 520-537.

Leonhardt, Andrä and Partners:  Pamphlet “Taktschiebeverfahren”.

Godden, W. G.:  “Construction”,  Structural Engineering Slide Library, International Structural Slides, Volume 2, Berkeley, California, 1980.  (Slides G34-G42 feature the construction of the Kocher Valley Bridge at Neuenstadt).
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Cable-Stayed With Concrete Deck

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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

 
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