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Keywords:
steel, cable-stayed, footbridge, hollow section, aesthetic, circulation, elements, coloration, environment |
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Summary
The paper deals with a project for bridging three Countries, Greece, Turkey and Bulgaria with a system of three cable-stayed steel footbridges, founding each one of each country separately, over the river ‘Evros’ at their frontier lines and meet in the common point in a small island formed in that river of those three countries. The bridging span has a length of 186.00m and a main double A pylon of 50.00m high of the deck for each footbridge and a common part with a three element pyramid pylon also 50.00m high and additional span of 174.00m. It is an advanced preliminary project which is made during the graduate session of a five students team and worked at the Steel Structure Laboratory of Demokritos University of Thrace in Greece according to the guidance of Professor E. Galoussis and Ass. Professor C. Kalfas.
General Description
Ιn the region of south-eastern Europe and more specifically in the north-eastern utmost of Greece a small island is formed in the river Evros called ‘Triethnes’, in which the frontier lines of three countries meet: Greece, Turkey and Bulgaria. Ιn this point it is forecasted to be constructed a system of three cable-stayed steel footbridges beginning each one of each country separately bridging the river and meet in a common point in the island, in the point of the section of these three countries. The region because of its geographical place as it is the common point of three different countries it constitutes a particularity. That particularity is reinforced with the peculiar geographic environment because of the existence of the river and an infrequent flora and fauna protected from international organisations for the protection of the environment and of the historical strategic importance as a part of a wider passage from Europe to Asia. For the exploitation of this point was born the idea for the construction of this system of bridges that aims to constitute a common point of meeting for cultural and tourist events with concert and exhibition places and other infrastructures of tourism and recreation. Intention, except from the easy access and the completed configuration of the landscape is to constitute a point of report in the direction of collaboration, solidarity and peaceful coexistence or these three different unions.
Fig.1 The area, the arrangement and a prospective view of the system
The choice of cable-stayed steel bridge was made first for the need for bridging a great length ~180.00m and secondly due to the morphology of the region. The initial idea of the simultaneous access in the point of union of three frontier lines of Greece, Bulgaria and Turkey, made the problem more complex since the functionality of the system should be combined with the static and constructional potentiality, the aesthetic, and finally the harmonisation within the particular environment, maintaining the initial objective. The initial aim of the bridge allows only the passage of persons for tourist and cultural mainly reasons and for safety and security reasons no passage of any type of vehicle it is forecasted. The deck is formed by four separate plane ‘warren’ type trusses with CHS elements. These four trusses form a box of trapezoidal cross-section with inclined sides of 1.50m the upper side, 6.00m the lower and 6.00m in height. The floor deck is made of wood bars and the railings of CHS elements with a small inclination to the inside avoiding the access to the deck edges and the cables. The forming shape of the deck improves the behaviour due to the wind effects, improves the aesthetics of the landscape especially with the suitable coloration and do not requires a big extent of worksite with inactive materials for disturbing the natural environment.
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