engleski

Innovations in Concrete Arch Bridge Design

There is a tradition of building large concrete arch bridges in Croatia. The buildability, maintainability and durability issues have been researched on several major arch bridges. Some important arch bridges and their specifics for the design development are given. The last accomplishment is the design for the Krka highway arch bridge near Šibenik (2004.) where all the positive experience from the Maslenica arch bridge (1996.) is accounted for. The composite superstructure for the Krka highway arch bridge, comprising steel girders and reinforced concrete deck-plate, enabled considerably smaller dimensions for the arch. The reduction of the total bridge dead weight was especially important, because the bridge location is in the zone of high seismicity. Full attention has been given to the detailing of all connections. In the design only details proven reliable in current practice in terms of durability, ease of construction, inspection, maintenance and repair are utilized, enhanced by explanatory notes and instructions. All steel members are designed to allow easy painting of all exposed surfaces. Steel corrosion protection has been adopted according to the latest standards for the most severe maritime environment. Specific corrosion protection specifications where given for each of steel girders surfaces, including the top flanges in direct contact with the concrete deck. In our opinion, the combination of the relatively light composite superstructure and the concrete arch presents an optimal solution for bridging very large spans, with full regard of environmental friendliness, functionality and aesthetics, if site conditions are favorable. Most bridges have a pleasant appearance when newly built, but after some years they develop their real character. Once the load bearing structural system has been chosen, the construction procedure is also known. The task of the designer is to propose and enforce appropriate reliable structural solutions that not only fulfill the statical requirements but are also durable for any adopted construction technology. The choice of adequate details is of utmost importance in attaining required durability with minimum maintenance. In Croatia some overcomplicated details, with unsatisfactory long term behavior are still repeatedly utilized in bridge construction, although there exist many sources of advice on good detailing. As modern mass production methods are increasingly applied in the construction industry, details tend to be repeated within projects and from project to project. It is therefore important to identify best practice and eliminate deficiencies. This approach usually leads to the slight increase of initial construction costs, but the overall costs that include maintenance will be significantly smaller.

inovations; concrete; arch bridges

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