The Preflex® Girder by CHRISTMANN + PFEIFER
One bridge girder – many possibilities: building durable, high-performance bridges with the Preflex® system
We love it when a plan comes together. And when that plan also follows a clear system, our enthusiasm knows almost no limits. And if – on top of everything else – that system has been successfully in use for more than 50 years? Almost indescribable.
What sparks this excitement? A prestressed composite girder. Sounds unusual? But that’s exactly what it is.
Our Preflex® girder is a true hidden champion – a reliable force working behind the scenes. A long‑running performer. But enough with the praise – because it’s all backed by solid engineering.
Intelligent bridge construction solution
We have been manufacturing the Preflex® girder since 1975, under the official approval of the German Institute for Building Technology (“DIBt”). Whenever large slenderness ratios combined with maximum stiffness are required, it shows its strengths.
Thanks to prestressing, the system makes full use of the tensile strength of structural steel, while the compression‑prestressed concrete tension flange ensures highly favorable crack behavior. A positive side effect: a significant increase in the stiffness of the “bare” steel girder.
Interested in the Preflex® girder?
Wonderful! We’d be happy to support you and look forward to receiving your inquiry.
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Application areas of the the Preflex® girder
The Preflex® girder is particularly suited for small to medium spans up to approx. 46 meters. This makes it ideal for road bridges, pedestrian bridges and railway bridges in this span range.
Road Bridges
For the superstructures, both T-beams and full-slab cross-sections are utilized. Normally, for pedestrian bridges, we endeavor to achieve the highest possible flexural rigidity with regard to the vibration behavior.
Railroad Bridges
Railroad bridges have been among the classic fields of application of the Preflex® girder since 1985. This is because it is not the ultimate limit state, but the fitness for purpose, that is the decisive factor for dimensioning the superstructure cross-section.
Prestressing the Preflex® girder ensures that the superstructure cross-section remains almost fully in condition I, which means that it therefore exhibits a correspondingly high moment of inertia.
Special use cases
When building a new hotel in Munich, the Preflex® girder is used in building construction to create a column-free ballroom ceiling. A video by the construction company Köster GmbH shows a summary of the assembly of the eight girders weighing up to 74 tons.
Successfully completed projects with the Preflex® girder
PREFLEX girders replace old bridge structure
Turning old into new: We supplied 8 PREFLEX® girders as the supporting structure for the new bridge over the river Lenne in the town of Lennestadt-Saalhausen in the Sauerland region of Germany. Each of the 8…
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Column-free ballroom ceiling made of PREFLEX girders
We have been manufacturing PREFLEX® girders for bridge construction for many decades and, thanks to this experience, we are of course aware of the performance of the double composite girder. We were able to…
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Inner-city bridge in PREFLEX construction method
For the new Hagen market bridge over the Volme, C + P designed and delivered 13 PREFLEX® Girders - each 33 meters long and weighing between 52 and 57 tons. As soon as particularly large slenderness with…
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Flood Bridge at the New Trade Fair in Dresden
Construction of a New Flood Bridge at the New Trade Fair Complex in Dresden Using the Preflex® Construction Method
In Dresden, CHRISTMANN + PFEIFER erected a streetcar bridge using the Preflex® construction…
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Discover more bridge building projects in the references section of our website.
How does the Preflex® construction method work?
In order to maintain the desired structural behavior, along with all of its associated benefits, the girder is prestressed by preflexing it. To do this, the steel girder is first elastically pre-bent in the direction of its subsequent deformation. In this condition, the tensioned chord is encapsulated with a loosely reinforced concrete chord.
The connection with the concrete is achieved through a welded headed stud connector. Following hardening and removal of the forces, the lower chord is prestressed. Double composite girders are created by supplementing the girders with cast-in-situ concrete. They can then be used as single or multiple span girders.
