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Saadiyat Bridge, Abu Dhabi, United Arab Emirates
Inclined piers constructed with system formwork
Abu Dhabi is one of seven emirates as well as being the capital of the United Arab Emirates which is situated on the Persian Gulf. The city has almost 1.5 million inhabitants and is located on an island, and has developed rapidly into a very progressive metropolis – like the neighbouring Dubai – over the past few years. Three years ago, the Emirates Palace Hotel was opened which is one of the largest and most luxurious hotels in the world and, as of 2009, the city will also host a Formula 1 Grand Prix race – examples which clearly show that Abu Dhabi ranks among the most modern cities world-wide.
500 metres off the coast of Abu Dhabi city is Saadiyat Island, which literally means the "Island of Happiness". The island has been artificially extended through a comprehensive landfill programme which, on the one hand, provides additional space for further development of Abu Dhabi and, on the other, the creation of an idyllic holiday destination complete with 29 luxury hotels and 8,000 villas over the next ten years. In addition, four museums and a performing arts centre are planned on Saadiyat as the main elements of a new international art and cultural centre. In order to form a connection between both islands, the Saadiyat Bridge is currently under construction.
The bridge construction
The 1,455 metre long, technically challenging construction has an impressive width of 60 metres – one of the widest bridges in the world. It provides enough space on one level for ten car lanes as well as two railway tracks. This means that travelling time from the city centre will be reduced from more than one hour to just a few minutes.
Eight foreland piers in the west and a total of eleven on Saadiyat itself serve to support the three pre-stressed concrete hollow boxes with spans ranging between 45 and 135 metres. The main bridge has a span of 200 metres with an overhead clearance of 26 metres in the bridge centre and is carried by two V-shaped, 20-metre high sets of triple identical piers per section. The inclination of each of the twelve individual supports is 27.45 degrees.
The consortium
The ambitious building project is being realised by a very committed project team, a consortium formed by Ed. Züblin AG and Saif Bin Darwish Civil Engineering Contractors. Within Ed. Züblin AG, project development is being handled by the company´s subsidiaries, Züblin International GmbH Stuttgart and Dywidag Bau GmbH, Bridge Construction, Nuremberg. The close co-operation of all those involved together with PERI engineers from Nuremberg, Weissenhorn and Dubai has proved to be extremely constructive both in the offer phase as well as the construction stage. This has meant that even planning changes that are made during construction do present a challenge for everyone but not, however, unsolvable problems.
The formwork and scaffolding
The PERI formwork and scaffolding solution for the inclined individual supports consists of two sets of VARIO GT 24 side formwork, a 7.76 metre wide, forward-inclined VARIO formwork element with integrated working platforms as well as a reverse-inclined raised formwork unit. This is based to a large extent on rentable standard material taken from the VARIO GT 24 girder wall formwork system and SLS heavy-duty spindles. Due to the large supporting angle, the high concreting loads are carried on the externally-positioned reverse-inclined formwork mounted on PERI UP shoring. Part of the steel girder framework installed by the contractors which cantilevers over the sea - steel profiles over 900 millimetres high - provides a safe support surface with correspondingly reliable load distribution.
The modular structure and the metric grid dimensions of the PERI UP modular scaffolding system make it possible to optimally adapt the load-bearing construction to the forces which are transferred via the raised formwork unit through the SLS heavy load spindles. 1.50 metre wide shoring towers are connected to form long supporting frame sections. Short, only 25 centimetre long ledgers contribute here to the bundling of the standards at the points where the loads are applied. Thus, the individual load-bearing capacity of 40 kN per leg can be virtually multiplied at will even for higher loads in the system without any time-consuming coupling of the scaffold tubes, as well as being adapted to the required load size. In connection with the high ledger rigidity of the PERI UP scaffold nodes, the scaffolding sections remain sufficiently stable in all situations. This means large scaffold units can be moved very quickly without their dimensional stability being impaired in any way.
The moving process
The 7.00 m x 3.00 m individual supports are constructed alternatively in four climbing steps with concreting heights of 4.70 metres – as well as by 2.44 metres in an outward direction in each case due to the pier inclination. The PERI concept therefore allows that the supporting frame construction is pulled outwards on the steel girders after striking has been completed as though being guided along rails. For efficient realization of the required supporting and platform levels, three tower modules each with a 2.00 metre base and a 4.65 metre extension height could be subsequently coupled together. The time-saving connection is carried out by means of a standard component taken from the PERI UP programme, the PERI section spindle. The extension units can therefore be accurately adjusted to the required height.
Through the extensively dimensioned moving units, using in part special cross-beams for the VARIO wall formwork elements, both the formwork and scaffolding can be brought efficiently to the next cycle. This means the altogether 48 casting segments can be very cost-effectively constructed with only four sets of formwork.
The PERI know-how is in demand, however, for all other construction phases as well – for both abutments, the numerous bridge piers in the foreland area through to the superstructure formwork. For the subsequent construction of the pre-stressed concrete hollow boxes, three different building methods are used: the western foreland bridge is realized using the incremental launching method, for the superstructure on Saadiyat Island in the east, falsework serves as a flat and even support, while the large spans in the middle bridge section are concreted by means of the balanced cantilever method.
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| PERI Systems In Use |
PERI UP Rosett Column Framework Unit
PERI UP Rosett Shoring Tower
VARIO GT 24 Girder Wall Formwork
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| Contractors: |
Consortium Ed. Züblin AG and Saif Bin Darwish Engineering Contractor |
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Field Service:
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PERI GmbH, Germany
PERI (L.L.C.), United Arab Emirates
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