Beitrag zur Entwicklung der Querschnittsgestaltung im Verbundbrückenbau

Die grafische Darstellung des Verbundquerschnittes mit einer oberen Betonplatte und einem darunter liegenden Stahlträger war seit seiner Vorstellung in den 1950er Jahren ein Symbol, das weit über die Theorie hinausging und weite Verbreitung in der Praxis des Verbundbrückenbaus fand. Seit den 1970er bzw. 1980er Jahren hat dieses Bild – bedingt durch neue und freiere Formen, Beton und Stahl miteinander zu kombinieren – seine Symbolhaftigkeit verloren. In Deutschland und Spanien wurde der Doppelverbund mit unten liegenden Betonplatten in Bereichen mit negativen Momenten eingeführt, in Frankreich werden Stahlträger auch in vorgespannten Betonquerschnitten eingebettet. Beide Ansätze haben dazu beigetragen, dass in der Gegenwart die Materialien Stahl und Beton im Verbundbau frei miteinander kombiniert werden können. On the development of sections in composite bridges. A comprehensive theory of composite construction was established in Germany by Sattler in 1953. The theoretical image of the composite section with a superior concrete slab and a lower metallic structure was shaped in addition to the analytical resolution. Theory and graphical representation were going to be known together in Europe. This figure was repeated in all theoretical and academic publications, so becoming an authentic icon of the composite section. Its translation to the bridge deck in flexion was obvious: the superior slab defines the tread platform, while the metallic structure was left off‐hook at the bottom. Nevertheless, in continuous decks the section is not optimal at all in zones of negative bending moments. But the overcoming of the graphical representation of the theory did not happen immediately. It was produced after a process in which several European countries played an active role and where different mechanisms of technological transference were developed. One approach to this overcoming is the “double composite action”, with a lower concrete slab in areas of a negative bending moment. The first accomplishments, a bridge in Orasje built in 1968 with 134 m span, as well as the publications of the system proposed by Fabrizio de Miranda in 1971 did not extend nor had continuity. Spanish bridges by Fernández Ordoñez and Martínez Calzón used double composite action for the first time in 1979. The German team of Leonhard, Andrä und partners, has used it since the end of the 1980's to solve bridges of great span. Once the technology has been well known thanks to the ASCE International Congress and the Spanish International Meetings organised by the “Colegio de Ingenieros de Caminos”, double composite action has been integrated well into the structural vocabulary everywhere. In France the approach was different. What Michel Virlogeux calls “double floor composite section” was reached as an evolution of prestressed concrete bridges. In an experimental process widely known, the external prestressing allows weight reduction by diminishing the thickness of the concrete webs. The following step, in the 1980's, was the substitution of the webs by metallic elements: stiffened plates, trusses or folded plates. A direct result of this development is the Brass de la Plaine Bridge in the Reunion Island in 2001 with 280 m span. Both approaches have contributed to a freedom of design in composite construction in steel and concrete today.     

Innovative Wege im Verbundbrückenbau

Innovative ways in composite bridge building. In the course of the introduction of the technical reports (DIN‐Fachberichte) commissioned by the Federal Ministry of Transport, Building and Urban Affairs and published by the committee of Deutschen Institut für Normung (DIN), several pilot projects have been implemented by DEGES (German Unity motorway planning and construction company) in the last couple of years. One of these selected projects is the 448 m long viaduct St. Kilian in the north of Schleusingen, Germany erected as part of the A73 federal motorway (BAB) project. Its striking design is a clear symbol of DEGES intention to erect architecturally designed engineering structures. In addition to the design, the building materials used and the method used for project execution are a clear reflection of the innovative ways followed by building owner, engineering offices and companies.     

Innovationen im Stahl‐ und Verbundbrückenbau

Innovations in steel and composite bridge construction: Accessibility of steel box girders for inspection and maintenance – New developments for the protection against corrosion. The German road transport network is one of the best and most efficient in the world. Roads are the lifelines of a vital economy. As an indispensable component of the transport infrastructure they ensure growth, prosperity and quality of life. In order to preserve or enhance its efficiency, it is necessary to constantly maintain and reconstruct the transport network as well as to upgrade and extend it. A modern road transport network is not conceivable without steel and composite bridges. These types of construction are used in many ways, their elements can to a large extent be industrially prefabricated, they are economically efficient and have a long service life. Owing to its low dead weight and its good load‐bearing capacity which makes it suitable for large spans, steel is a material which is widely used for the construction of large bridges. But for the design of smaller bridges, too, steel is a good material whereas composite materials are generally used for medium‐span bridges. Steel and composite bridges are in economic competition with other types of construction. Economic efficiency decisively depends on the constructional design and the whole life costs. This article provides information on current regulations which have to be observed for the construction of steel box girders, on the development of new coating systems and on the hot dip galvanising of components which are subject to dynamic stresses.