Complejo Zárate - Brazo Largo
Coordinates: 34 ° 6 ′ 13 ″ S , 59 ° 0 ′ 10 ″ W.
| Complejo Zárate - Brazo Largo | ||
|---|---|---|
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| Official name | Complejo Union Nacional | |
| use | Railway u. Road bridge | |
| Crossing of | 2 arms of the Río Paraná | |
| place | Zárate - Brazo Largo | |
| construction | 2 identical cable-stayed bridges | |
| overall length | 30.4 km | |
| Longest span | 110 + 330 + 110 m | |
| Clear height | 53 m | |
| start of building | 1972 | |
| completion | 1977 | |
| planner | Fabrizio de Miranda | |
| toll | toll | |
| location | ||
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The Complejo Zárate - Brazo Largo is the frequently used name for a structure consisting of two combined railway and road bridges over two branches of the Río Paraná , long foreshore bridges and a dam over the 25 km wide Talavera Island in between, with which the connection between the Argentine provinces of Buenos Aires and Entre Ríos or the part of Mesopotamia .
location
The building starts on the outskirts of the m on a high plateau about 25 on the right bank of the Paraná de las Palmas located Zárate and the small station ends after 30.4 kilometers near Brazo Largo on the marshy plain north of the Río Paraná Guazú .
Before the connection opened in 1977, there was only one train ferry between Zárate and Puerto Ibicuy further up the river . In Argentina, the Túnel Hernandarias, which opened in 1969, was the first fixed connection over the Río Paraná between Santa Fe and Paraná, which is 380 km further upstream . In 2003, the Rosario-Victoria Bridge, now only 220 km upstream, was opened to traffic.
Surname
The official name was initially Complejo Ferrovial Zárate - Brazo Largo , because at first only a fixed railway connection between the Ferrocarriles Mesopotámicos and the Ferrocarril Central de Buenos Aires was discussed. In 1995 the name was changed to Complejo Union Nacional .
description
Cable-stayed bridges
The most important parts of the connection built between 1972 and 1977 are two identical cable-stayed bridges , namely the Puente General Bartolomé Miter over the Río Paraná de las Palmas and the Puente Justo José de Urquiza over the Río Paraná Guazú , which were designed by the Italian engineer Fabrizio de Miranda were erected. Fritz Leonhardt and his office were involved in the implementation planning of the steel superstructure and the construction supervision.
The two bridges were the first cable-stayed bridges with combined road and rail traffic, the first cable-stayed bridges with steel superstructures and concrete pylons and the first in a series of technical aspects.
On the upstream side, they carry a railroad track separated by a grid and next to it a four-lane road, which is divided into two lanes by crash barriers and accompanied on both sides by a narrow walkway protected by crash barriers.
Its main openings have spans of 330 m, the side openings of 110 m. The bridges have a clearance height of 53 m.
Its 122 m high pylons consist of two rectangular steel concrete -Stielen with hollow cross section that are on base plates up to 70 m into the ground reaching bored piles were founded. The posts are connected and stiffened below the deck slab by a crossbar made of reinforced concrete and just below their tips by a steel St. Andrew's cross . On the tips of the stems there are steel boxes in which the anchors for the tufted stay cables are housed. Large floating ship deflectors at a distance of several meters in front of the pylons serve to protect against ship collisions.
The steel deck is 22.6 m wide and has a construction height of only 2.6 m. It consists of a 14.8 m wide orthotropic plate between two trapezoidal hollow boxes , the lower chords of which are connected by a torsion bond with diagonal struts and cross members in the area of the rope anchors. The hollow boxes are stiffened on the inside in the longitudinal direction by trapezoidal profiles and in cross section by bulkheads at intervals of 3.143 m. The shape of the girder is the result of extensive aerodynamic studies and tests that were finally carried out on a 16.5 m long model of the entire bridge on a scale of 1: 33.3 in Bergamo . The braking forces of traffic on the road slab are transferred to the pylons by hydraulic dampers.
For the first time in the construction of large bridges, factory-made parallel wire bundles in PE ducts with HiAm anchors were used as stay cables, which had proven themselves elsewhere. The individual ropes contain different numbers of wires depending on their load. The arrangement of the 72 ropes of each bridge differs in details from the usual pattern: on each pylon post, a vertical rope is anchored to a small cantilevered girder below the St. Andrew's cross and to the track girder in the space between the pylon post. Towards the middle of the main opening, there are seven stay cables on both sides, which are anchored in the pylon tops and at the same intervals of 22 m on the roadway girder, but the last three cables on the side of the railway are designed as double cables. Over the considerably shorter side openings, the last three of the seven ropes, which are also seven ropes, are combined to form parallel ropes arranged directly one behind the other, whereby they are again designed as double ropes on the railroad side.
At both ends of the cable-stayed bridge, massive reinforced concrete portals serve as pillars and tie rods for the deck girder and at the same time as the first pillars of the ramp bridges.
Ramp bridges, connecting road
The access ramps for the railroad and the four-lane road are designed as separate viaducts with different gradients , as a road can have a greater gradient than a railroad track. Their construction principle, however, is always the same: prefabricated prestressed concrete girders are suspended on a row of pillars at center distances of 65 m, but because of the large pillar tables they only have a span of 45 m. In the case of the railway viaduct, the track is supported by a girder on individual pillars, while in the wider road viaduct, several girders lying next to each other are each supported by three pillars arranged next to one another. All pillars along the entire route were built on large bored piles.
The railway viaducts are 9.9 km long and the road viaducts 6.4 km long. Between Zárate and the Puente General Bartolomé Miter , the railway viaduct is 1,452 m long and the road viaduct is 1,214 m long. On the low-lying Talavera Island, the first railway ramp is 2788 m, the second to the Puente Justo José de Urquiza is 2836 m long. The two road viaducts on the island and the one north of the Puente Urquiza have a length of 1733 m. After the cable-stayed bridge, the 2835 m long northern railway viaduct describes a narrower left curve than the road, crosses the access to the port facilities of the Portuaria del Guazú terminal and turns to the northwest in the direction of Brazo Largo, which is 6.7 km away.
For the construction work, a canal crossing almost the entire island was created along the route, which made it possible to move the necessary material and equipment into the previously impassable area and to create the dam required for the track as well as the road.
The four-lane road over the island of Talavera has two directional lanes separated by a narrow green strip, mostly without guard rails.
Broken rope in 1996
In November 1996, one of the stay cables of the Puente Justo José de Urquiza broke without prior notice above the lower anchorage. The rope was replaced as soon as possible, later a total of 13 ropes were replaced. This event caused a sensation in the professional world mainly because rope breaks are usually announced in advance, which is why it was classified as extremely rare.
Web links
- Zárate-Brazo Largo Bridge I. In: Structurae
- Zárate-Brazo Largo Bridge II. In: Structurae
- Zárate-Brazo Largo Bridges across River Paraná, Argentina (1972-77) on: NISEE, National Information Service for Earthquake Engineering, University of California, Berkeley
Individual evidence
- ↑ a b c d e f g Fritz Leonhardt, Wilhelm Zellner, Reiner Saul: Two stay cable bridges for rail and road traffic over the Rio Paraná, Argentina. In: Stahlbau 48 (1979) , Issues 8 and 9, pp. 225-236, 272-277
- ^ Karlheinz Roik, Gert Albrecht, Ulrich Weyer: Cable-stayed bridges . Ernst, Publishing House for Architecture and Technical Sciences, Berlin 1986, ISBN 3-433-00924-4 , p. 37
- ↑ HiAm is the abbreviation for High Amplitude
- ^ Henrik Andersen, Dietrich L. Hommel, Ejgil M. Veje: Emergency rehabilitation of the Zárate-Brazo Largo Bridges, Argentina. Presented at the IABSE Conference, Malmö 1999 . doi: 10.5169 / seals-62172