Rehabilitation of the Ramalho Ortigão Viaduct




2021-05-20
The Ramalho Ortigão Viaduct is an overpass carrying a high volume of traffic. The viaduct goes over one of the main Lisbon, Portugal, city center access routes (Avenue Calouste Gulbenkian), which itself has high daily traffic levels. The original viaduct was designed by Engineer Edgar Cardoso and was built by the company Empec in 1972. The viaduct is 400 ft (112 m) long, its deck measures 80.7 ft (24.6 m), wide and has an obliqueness of 45 degrees. The available crossing width between the faces of the pillars/abutments is 232 ft (70.7 m). The longitudinal system comprises two longitudinal, prestressed, reinforced concrete cantilever beams and a central reinforced concrete simplysupported span. The location of the expansion joints coincide with the supports of the central span. The structure is extended in the pillar/abutment zones through cantilevers fixed at their ends to a foundation beam. The two longitudinal cantilever beams have a 116 ft (35.4 m) long overhang supporting the central section, which has a span of 32.8 ft (10 m). These cantilever beams start at an elevation of 13.7 ft (4.2 m), and the height is 5.3 ft (1.6 m) at their ends. The variation in height of the box girder is attained through a parabolic curve, and the height at the center of the central section is 5.1 ft (1.5 m). The transverse section is formed by a tri-cellular box girder 26.2 ft (8 m) wide with two cantilever beams, each 27.2 ft (8.3 m) wide. Next to the box girder, the transverse cantilever beams are 2.13 ft (0.65 m) high whereas at their edges, where there are trapezoidal section kerb beams, they are 7.1 in. (0.18 m) high. The transverse cantilever slabs were cast with 24 cylindrical pipes arranged along the main axis of the construction, interrupted by transverse ribs 5.9 in. (0.15 m) wide at 4.1 ft (1.25 m) intervals along the length of the construction, forming a grid of ribs in the two main directions. Next to the expansion joints of the central section, the transverse cantilever beams are solid for 3.9 ft (1.2 m) of their length. The box girder webs are 1.3 ft (0.4 m) thick. The thickness of the lower flange varies, while the upper one is of constant thickness throughout the entire length of the construction. The upper flange of the central cell is solid, while the lateral cells have an upper flange with four rows of castings and transversely varying height, with the greatest height being on the transverse cantilever beam side. The pillars/abutments have a U-shape cross section and its direct foundations have a rectangular section with 18.9 x 9.6 ft2 (5.8 x 2.9 m2). On the back of the pillars/abutments, the cantilevers are 1.3 ft (0.4 m) thick and extend the walls of the tri-cellular box girder, with lengths and heights varying according to the alignment. These walls take the passive anchoring of the platform’s longitudinal prestressing at various heights and in different longitudinal positions, and they are prestressed in the vertical direction between the footing and their top....

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