Doka forms for landmark project
01 December 2004
Doka Table Forms have provided outstanding performance during their debut performance in Qatar, through playing a crucial role in meeting a demanding programme for the construction of the prestigious Four Seasons West Bay complex.
“The use of Doka’s systems has helped local contractor Construction Development Company (CDC) to achieve the seven-day floor cycles needed for construction of the major complex, which includes a high-rise hotel, office and apartment buildings surrounded by luxury facilities,” says a spokesman for Doka.
CDC has used a wide range of Doka equipment to form all of the slabs, beams, columns, shafts and rafts within the towers and associated buildings of the development, which stands on a 55.4-hectare site in a prime development area of Doha.
CDC began its contract in July 2001 and work is now nearing completion, providing a dramatic new focus for the West Bay skyline, says the spokesman.
CDC has carried out the work in parallel across all sections of the site and Doka equipment has been central to ensuring that the operation has kept to schedule. From the initial supply negotiations, sealing the order, timely delivery of materials, down to technical assistance and site supervision, Doka has been efficient and solid in their support,” says a spokesperson for the project.
Hotel complex
Situated at the centre of the complex, the Four Seasons Hotel stands is set in landscaped grounds and flanked by a pair of 22-level apartment blocks and the tallest building – the 28-floor office tower.
The contractor has ensured optimum economy by taking advantage of Doka’s flexible arrangements, which enabled it to rent some of the equipment while buying other items. CDC purchased the Doka systems that have been used as formwork for the main bodies of the towers. Rental arrangements were used for the formwork for beams and slabs in the lower and plaza levels within the tower footprints. Rented formwork was also used for many other one-off areas.
Each tower had its own sets of Doka formwork, with the exception of that needed for the raft foundations. This was reused in each of the main buildings, says the Doka spokesman.
Qatar debut
The Four Seasons Hotel, has 18 floors, plus lower and plaza levels, giving a gross floor area of 46,340 sq m. Doka formwork has been in use throughout the structure, including the Dokaflex Table system which has made its Qatar debut on the project.
Dokaflex is one of Doka’s most important innovations in recent years, and makes for highly efficient forming of floor slabs, because the tables are pre-assembled and can be repositioned very quickly using a shifting trolley.
Doka supplied 1,568 sq m of the Dokaflex Table formwork plus one set of shifting equipment for the forming of the hotel’s beams and 300 mm-thick slabs.
Doka’s Top 50 Large Area wall formwork has been used for casting the walls and columns. Top 50 is made-to-measure formwork from a modular system, which can cater for a vast range of applications. The shape, size, anchor pattern and sheeting of the panels can be adapted to suit any set of requirements.
Column and wall formwork had form heights of 3.4 m and 3 m, to suit the building’s 3.35 m floor-to-floor heights. CDC bought sufficient quantities to form half of a typical floor in the hotel – 14 columns, using 366 sq m of wall formwork. This proved sufficient to meet the seven-day floor cycle demanded by the tight schedule. However, CDC bought sufficient beam and slab formwork for the entire floor area of the hotel, as well as enough of the Eco 20 300 floor prop system for re-propping, he says.
The hotel’s shafts were formed using Top 50, which was climbed ahead using telescopic shaft beam internally and the 150 F climbing brackets externally.
CDC bought a sufficient quantity for one and a half times the two typical floor shafts.
Apartment towers
Standing at 22 levels, each apartment block has a gross floor area of 19,052 sq m. One has been designated primarily for single businessmen and the other for families. The apartments used the same Doka Table and Top 50 systems as the hotel, and the floor-to-floor heights are the same at 3.5 m.
As in the hotel, sufficient column formwork was bought to form 50 per cent of the typical floor, while the other systems were bought in sufficient quantities for an entire level. Beam depths are 700 mm and the slab depths vary between 200 mm and 300 mm. The apartments have needed a greater quantity of shaft formwork than the hotel, though the amount of floor area formwork needed was smaller, at 1,024 sq m per tower against the hotel’s 1,568 sq m.
Office tower
With 28 storeys as well as the lower and plaza levels, the office tower is the tallest building on the site. “As elsewhere, Doka Top 50 Large Area wall formwork has been used for columns, although in this case CDC had bought enough for 100 per cent of the columns in a typical floor, instead of the 50 per cent in the other structures,” says the spokesman.
“The shaft construction is much bigger in this building, with 2,976 sq m of formwork supplied. This was designed with a form height of 4.6 m, to create the higher floor-to-floor height of 4.25 m needed in an office building. The shaft uses the same Top 50 climbed-ahead Doka system as in the development’s other towers,” he adds.
The office building’s beam and slab formwork was made up of Dokaflex 20 for the internal work and Dokaflex Table for the external drop beams. One set of shifting equipment was supplied. Doka also provided the Eco 20 300 floor prop system for the office building for re-propping.
Lower and plaza levels under all four buildings have been cast using Doka d2 Tower and timber beam H20 equipment. The proven d2 load-bearing Tower combines with all Doka floor-system superstructures. Its characteristics include easy erection and enormous versatility, the spokesman says. This equipment was all rented, and between 1,024 sq m and 1,568 sq m was needed for each of the four towers. The slab thicknesses varied for the four buildings - a 300 mm depth was adopted in three of the buildings, while the office block was given a depth of between 130 mm and 200 mm. Beam depths are between 500 mm and 1.25 m deep depending on the location, and the floor-to-floor heights range from 5 m in the apartment block lower levels to 9 m in the office tower, he says.
The d2 Tower system was also used in other areas. It was adopted in combination with Dokaflex 20 for the forming of beams and slabs in the ballroom and many of the recreational areas, as well as for the podiums outside the towers’ footprints.
For the towers’ rafts, Doka supplied 1,500 sq m of Top 50 large area formwork, which was sufficient to cover half of the hotel’s foundation.
“This was reused for the other towers, further aiding the efficiency of this massive and successful formwork operation,” he concludes.
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