Orthotropic steel bridges

In the 1920’s, American engineers began using steel plate riveted to steel beams for large movable bridges. The purpose was to minimize the dead load of the lift span. In 1938, the American Institute of Steel Construction (AISC) began publishing reports on the steel-deck system. AISC called this the “battledeck floor” because it felt the steel deck had the strength of a battleship. The orthotropic deck was a result of the ‘battledeck’ floor. This floor consisted of a steel deck plate, supported by longitudinal (normally I-beam) stringers. In their turn, these stringers were supported by cross beams. Following World War II, German engineers developed the modern orthotropic bridge design as a response to material shortages during the post-war period. The orthotropic deck reduced the weight of continuous beams considerably and permitted spans and slenderness ratios unknown until then. At first open rib longitudinal stiffeners were used, later the closed stiffeners with a higher torsion stiffness were introduced.

Modern steel deck bridges consist of a 10-14 mm steel deck plate supported in two perpendicular directions; by ‘crossbeams’ in the transverse direction and by stiffeners in the longitudinal direction. To support the steel deck crossbeams are welded to the structure every few meters (typically 2-4 m). The loadin the crossbeams is transferred into the longitudinal main girders, which form the main support of the bridge. Therefore, the elastic properties of the steel deck structure in the two orthogonal directions are different. In other words, the steel deck structure is an orthogonal and anisotropic plate, for short it is called an orthotropic plate. The deck plate forms the top flange of the bridge deck. There are different types of bridge deck structure; most of them vary in the form of the longitudinal stiffeners. These longitudinal stiffeners can be divided into two types: open stiffeners such as flat bars, angles and bulb sections and closed stiffeners with a trapezoidal, V or rounded form.



Downloads Ferroplan

Brochure (A3/2-Sided/short edge binding)




Fatigue is a well known phenomenon related to orthotropic bridge decks and is a worldwide problem. Several bridge cases are known and, despite years of research made in the Netherlands, United Kingdom, Hungary, Japan, Brazil and many other countries, a good solution was, until now, not available for a fast and definite rehabilitation.  

Since 1999 a large research project is executed in the Netherlands to develop a new revolutionary application for the Contec Ferroplan®. The Contec Ferroplan® is used as a wearing course (60 - 100 mm) on orthotropic steel bridge decks and is elongating the service life of the total construction by solving fatigue problems in specific deck details. Project initiator is the Civil Engineering Division of the Dutch Ministry of Transport, Public Works and Water Management in close co-operation with Contec ApS, the founder and designer of the Contec Ferroplan®, the Delft University of Technology, TNO Building and Construction Research and various contractors in the Netherlands and Germany.  The Contec Ferroplan® was found to be a very promising solution because it turns the deck plate in a much more rigid construction with a higher “plate factor” due to the monolithic composite interaction between the Contec Ferroplan® overlay and the steel deck plate of the orthotropic steel bridge deck. The strengthening of the deck plate with the Contec Ferroplan® will result in a large reduction of stresses in the deck plate and the stiffeners. After 6 years of research and tests, including a pilot project in 2003 and large test area's with different types of placing equipment, the Contec Ferroplan® solution has been described and is used for the re-strengthening of several large bridges in the Netherlands in the period 2005 – 2008 (> 40,000 m2). The Contec Ferroplan® can be placed with different types of equipment like slipformpaver, vibration screed and laserscreed, this make it possible to rehabilitate large orthotropic bridge decks in a very short time. More detailed information can be found under Projects and under Download where different proceedings and papers about this project can be downloaded.  The rehabilitation and re-strengthening of an orthotropic steel bridge deck is absolutely not a standard application for the Contec Ferroplan®, the rehabilitation of infrastructural constructions like a bridge in a highway system is a specialization  and investigation must be made from case to case to avoid failures. Since every project will be an unique project with a different situation, a general description cannot be made and also details like the inspection, repair of cracks and finite element calculations are not part of the knowledge and/or are not the specialism of Contec ApS. For that reason we recommend to involve specialist from different disciplines like qualified engineering companies, research institutes and contractors with sufficient knowledge. Contec ApS is willing and able to work like an intermediary between bridge owners at one side and engineering firms, contractors and research institutes on the other side to create a skilled building team and thus “bridging the gap”.