Work pioneering Stuttgart-Degerloch bridge awarded
The Stuttgart-Degerloch span railway bridge has been awarded with the German Civil Engineering Award 2022 for its innovative design of mesh arch bridge with Helvetic carbon fiber reinforced polymer cables.
An absolute first, also made possible by the experts at Empa and its spin-off Carbo-Link AG with many years of research and development work.
The 127-meter-long Stuttgart-Degerloch rail bridge, was installed on the A8 highway in Germany, is the world’s first network arch bridge that rests entirely on tension members made of Teijin’s Tenax carbon fiber-reinforced plastic by Carbo-Link AG of Fehraltorf, Switzerland.
The jury of Germany’s major state award for structural engineering explained its decision by stating that “as an innovation, the mesh arch bridge with carbon fiber-reinforced polymer cables and carbon hooks is a globally successful example of civil engineering and provides formative answers to current issues in civil engineering.”
The prize, worth 30,000 euros, was awarded to the Stuttgart-based engineering firm Schlaich Bergermann Partner (Sbp), which built the bridge from the initial designs to the finished structure, with the active support of experts from Empa and the Fehraltorf-based company Carbo-Link AG, which was established as an Empa spin-off and was able to contribute its expertise with carbon fiber-reinforced polymers (CFRPs).
Cooler summers in the city thanks to appropriate building materials
One idea, many experiments
Originally, the bridge was designed with conventional steel hooks before Lorenz Haspel of the sbp team came up with the idea of replacing the steel cables with prestressed CFRP hooks.
The starting point for extensive preliminary work was unusual: for new products and constructions of this type, approval from the building authority is required in Germany, but in this case a “special permit” was issued for this completely new building project, which in turn required detailed proof of suitability.
In October 2016, Empa experts led by Masoud Motavalli of the “Structural Engineering Research Lab” initiated experiments that also simulated the long-term use of the prototypes in railway operation and the associated loads. Empa reviewers Urs Meier-a pioneer of CFRP research-and Peter Richner, now deputy director of Empa, analyzed and evaluated the extensive data. In addition to the “fatigue” properties of CFRP ropes, they also paid attention to issues related to weathering, lightning or fire resistance; they also considered the influence of electric and magnetic fields and vandalism.
In May 2017, Meier and Richner finally sent their expert report to Stuttgart, and a little less than a year later came the letter from the Baden-Württemberg approval authority authorizing the use of CFRP hangers in the construction of the A8 highway bridge, subject to certain conditions.
A sustainable and cost-effective support structure
Although cost issues challenged the design, in the end it turned out that the variant of thin CFRP suspension cables was ultimately more economical than a construction with conventional steel cables.
The new CFRP bridge also leads the way in terms of sustainability: EMPA (Swiss Federal Institute for Materials Research and Testing, Switzerland) has calculated that CO2 emissions from production are only one-third of those from the steel solution, and energy consumption is more than halved.
Given the advantages of carbon fiber-reinforced polymers, CFRP pioneer Urs Meier believes they will gradually gain further areas of application in the construction industry, just as has happened in aircraft construction. According to the expert, being awarded the German Civil Engineering Prize should encourage this process.
SWISS to be the world’s first airline to use Synhelion solar fuel
A major award of excellence
The German Civil Engineering Award “Deutscher Ingenieurbaupreis” is a prestigious prize awarded every two years and was presented for the fourth time under the joint sponsorship of the Federal Ministry of Housing, Urban Development and Construction and the Federal Chamber of Engineers.
The competition process was conducted by the Federal Office of Building and Regional Planning, with a jury of seven recognized experts.
In addition to the main prize for the Stuttgart Bridge, three prizes were awarded, each with a prize pool of 5,000 euros, and a recognition prize of 3,000 euros.