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Roads overpassing highways or speedways are rather a common case, as such bridges occur in average every 2 km of highways in densely populated areas. Due to the high number and similar boundary conditions, the design and realization tends to be standardized and repetitive. The total length ranges mostly between 40 and 55 m, whereas the construction height is a limiting factor since minimumclearance heights must be guaranteed both for safety as well as for driving comfort. Due to these reasons, highway overpasses have been a field of application where steel-framed composite decks have proventheir efficiency for this task. Starting from Germany, the VFT technology (prefabricated composite beam) has spread in several European countries in the last decades as further development of the standard steel-concrete composite solution. Its configuration fits perfectly to integral frame bridges built over existing infrastructure with the scope to minimize the traffic disturbance. In this paper a further step is proposed: the VFT-RS technology. The change consists in using standard rolled sections by adapting them into the integral frame bridge configuration, further enhancing the structural efficiency with the benefits of high-steel strength. The possibility of weathering steel or hot-dip galvanization create the unique offer of a maintenance-free solution.
This paper introduces (both formally and technically) a new concept: a hybrid steel–concrete cross section. The definition is based on the shear force transmission mechanism and it assumes the existence of a new type of shear connections, i.e. composite dowels. The hybrid cross-section is a generalization of composite steel-and-reinforced concrete cross sections and it is defined by a new way of dimensioning for vertical shear. The hybrid cross section concept is based on a specific approach to the lever arm of internal forces and an assumption that the local shear transfer mechanism of composite dowels is different than in the case of classic welded studs. The concept makes it possible to show by design calculations that the shear force is transferred through jointly the concrete part and the steel part. It is worth emphasizing that the proposed concept is a response to the new opportunities provided to engineers by composite dowels and to the fact that the bridge structures designed nowadays are different from the ones designed previously. The concept enables the design of completely new types of composite steel–concrete beams. The presented theoretical analyses verified by means of FEM show how the change of the shear connection level influences the division of the shear force in the cross section. This is included in the design concept through the internal lever arm of the hybrid section. The proposed concept has been shown to be internally consistent and complete.
Composite dowels have opened new possibilities for engineers designing composite structures. The fundamental and most important characteristic of composite dowels is the shape of the cutting line. It is important to understand why only one particular shape of the cutting line is used in bridge engineering, while so many different shapes have been investigated by many researchers. The essential part of the process of developing composite dowels – the development of the shape of the cutting line – is presented in this paper. The influence of the steel web thickness is presented, and technological problems of steel fabrication are highlighted. The role of empirical experience from the first bridges, push-out tests, and finite element simulations is presented. Assumptions for numerical procedures are given. The distinction between the steel failure and concrete failure modes is introduced for composite dowels. The paper presents how the concept of “shape” was divided into “shape,” “ratio,” and finally “size,” and how, because of the fatigue problems in bridges, all the three factors have emerged to result in the form of shapes that can satisfy the requirements for bridges. Research leading to the invention of the first version of the clothoidal shape is presented.
Starting from Germany, the VFT® bridge girder technology (prefabricated composite beam) has spread in several European countries in the last decades as further development of the standard steel-concrete composite solution. Its configuration fits perfectly to integral frame bridges built over existing infrastructure with the scope to minimize the traffic disturbance. In this paper a further development with the focus on cost efficiency in span ranges of 40-55 m is proposed: the VFT-RS technology. The change consists in using standard rolled sections by adapting them into the integral frame bridge configuration, further enhancing the structural efficiency with the benefits of high- steel strength. The constructive details to achieve the polygonal form have been studied to allow easy fabrication and a maximal clearance height over highway traffic lanes. The VFT-RS solution is conceived as the economic option of standard highway overpasses, with the aim of an overall construction cost reduction of 5%.
Stählerne Rahmenbrücken kommen in Deutschland bereits seit Anfang des letzten Jahrhunderts zum Einsatz. Wurden die ersten stählernen Rahmen noch genietet, konnten Anfang der 1940er-Jahre mit geschweißten, vollwandigen Zweigelenkrahmenbrücken bereits Spannweiten bis 50 m realisiert werden. Mit ihrer Schlankheit kamen sie u. a. dann zum Einsatz, wenn gestiegene Anforderungen an die Verkehrslasten einen Ersatzneubau erforderten. Waren die Lagerungsbedingungen von den zunächst errichteten Zweigelenkrahmenbrücken noch klar definiert, so erforderte der Bau von Brücken mit integralen Widerlagern die Entwicklung neuer Ansätze zur Berücksichtigung der Boden-Bauwerk-Interaktion. Heute sind Rahmenbrücken wegen der großen realisierbaren Spannweite, welche den Mittelpfeiler bei Autobahnüberführungen überflüssig macht, sowie ihrer geringen Lebenszykluskosten zu einer wirtschaftlichen Alternative geworden. Die hier vorgestellte kurze Geschichte der Rahmenbrücken erhebt keinen Anspruch auf Vollständigkeit, soll jedoch an ausgewählten Beispielen die Entwicklung in den letzten 100 Jahren anschaulich nachzeichnen.
Introduced to construction about 20 years ago, the composite dowels shear connection is now used more and more widely in engineering, mostly in bridge construction. During this time, production and construction technologies were refined, design guidelines were developed, and finally a new Technical Specification CEN/TS 1994-1-102 was established. This paper summarizes the experience and design principles related to the steel part of the connection, focusing on the latest achievements in recent years: technology of production, solutions and design approach.
Im Zuge der Hochwasserschutzmaßnahmen entlang der Salzach wird zur Überführung der Straße von Zell am See nach Kaprun in Österreich eine neue Brücke mit größerer Stützweite notwendig. Der Ersatzneubau der Brücke über die Salzach bei Mayereinöd ist ein Trogbauwerk in Verbundbauweise, dessen Form funktional entworfen wurde. In Querrichtung werden vorgefertigte π-Platten mit externer Bewehrung gewählt, um eine große Schlankheit und eine schnelle Bauzeit zu ermöglichen. Die externe Bewehrung wird feuerverzinkt ausgeführt.
Das ECF-Schienenbefestigungssystem wird bei festen Fahrbahnsystemen aus Stahl eingesetzt, bei denen ein Höhenausgleich durch aufgeschweißte und in Vergussmaterial eingebettete Gewindebolzen erfolgt. Unter außerplanmäßig hoher Beanspruchung können Teilabrisse oder Komplettabrisse dieser Bolzen auftreten. Zur Erkennung eines Abrisses unter laufendem Verkehr bedarf es einer robusten Prüfmethode.
Im Rahmen der vorliegenden Untersuchung wurde eine sensorbasierte, transiente Thermografie zur kontinuierlichen Überwachung der Aufschweißbolzen entwickelt und bewertet. Die Methode basiert auf der gezielten Erwärmung des Bolzenkopfes durch eine Heizpatrone und der Erfassung der resultierenden Wärmeausbreitung in der Grundplatte. Durch schrittweises Einschneiden der Bolzen konnten charakteristische Temperaturgradienten erzeugt werden, die eine differenzierte Identifikation von Teilabrissen und Ablösungen ermöglichen. Die methodische Einfachheit, Robustheit und Kosteneffizienz der eingesetzten Sensorik prädestinieren die Methode für diesen Anwendungsfall, weshalb sie auch aktuell an einer Eisenbahnüberführung eingesetzt wird.
Integral bridge with RS-Overpass technology : step into the future of standard highway overpasses
(2023)
Starting from Germany, the VFT bridge girder technology (prefabricated composite beam) has spread in several European countries in the last decades as further development of the standard steel-concrete composite solution. Its configuration fits perfectly to integral frame bridges built over existing infrastructure with the scope to minimize the traffic disturbance. In this paper a further development with the focus on cost efficiency in span ranges of 40-55 m is proposed: the RS-Overpass technology. The change consists in using standard rolled sections by adapting them into the integral frame bridge configuration, further enhancing the structural efficiency with the benefits of high-steel strength. The constructive details to achieve the polygonal form have been studied to allow easy fabrication and a maximal clearance height over highway traffic lanes. The RS-Overpass solution is conceived as the economic option of standard highway overpasses, with the aim of a overall construction cost reduction of 5%. The possibility of weathering steel or hot-dip galvanization create the unique offer for a maintenance-free solution.
