By Colin Foreman
The new Four Seasons Hotel in Doha’s upmarket West Bay Complex is now set to open during the first quarter of 2005. To get the structures completed on time the contractor had to achieve seven-day floor cycles. Construction Week learns how it was done.
Constructing a hotel to last for all four seasons|~||~||~|Construction Development Company (CDC), a Qatar-based contractor, achieved seven-day floor cycles with Doka Table forms during the construction of the Four Seasons West Bay complex in Doha.
The system helped the contractor on the construction of the major complex, which includes high-rise hotel, office and apartment buildings surrounded by luxury facilities. 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.
The development stands on a 55.4 hectare site in a prime development area of Doha. CDC began its US $137 million contract in July 2001 and work is now nearing completion, providing a dramatic new focus for the West Bay skyline.
There are both Islamic and Qatari influences in the design of the complex. The concept is based on the Alhambra, the Moorish palace-citadel in Granada, Spain, which brings together elements of a fortress, residential area and palace into a single complex. Just like the Moorish palace, the Four Seasons West Bay project combines many roles. It includes townhouses, a marina, health club and spa as well as the four focal towers containing the hotel, offices and apartments.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,” said a spokesperson for the project.
The Four Seasons Hotel stands at the centre of the complex, set in landscaped grounds and flanked by a pair of 22-level apartment blocks and the tallest building, the 28-floor office tower. The hotel will have 230 guest rooms as well as suites and other facilities such as restaurants, a tea lounge, cigar bar and lounge, a grand ballroom and meeting rooms. The inclusion of five presidential suites and a Royal suite emphasises the hotel’s prestige as one of the world’s most luxurious places to stay. Completing the development are 20 three-storey townhouses, a hundred-berth marina and the other splendid leisure facilities.
The contractor 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.
The Four Seasons Hotel, the central feature of the complex, has 18 floors, plus lower and plaza levels, giving a gross floor area of 46,340 m2. 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 of recent years. It 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 1568 m2 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 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. 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 m2 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.
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.Both apartment blocks stand on 22 levels and each has a gross floor area of 19,052 m2. One has been designated primarily for single businessmen and the other for families.
The apartments each used the same Doka Table and Top 50 systems as the hotel, and the floor-to-floor heights are the same, 3.5 m. As in the hotel, sufficient column formwork was bought to form 50% 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 1024m22 per tower against the hotel’s 1568 m2.
Tallest building on the site is the office tower, which has 28 storeys as well as lower and plaza levels. As elsewhere, Doka Top 50 Large Area wall formwork has been used for columns, though in this case CDC bought enough for 100% of the columns in a typical floor, instead of the 50% in the other structures. The shaft construction is much bigger in this building, with 2976 m2 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.
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. This equipment was all rented, and between 1024 m2 and 1568 m2 needed for each of the four towers. Slab thicknesses varied. A 300 mm depth was adopted in three of the buildings, while the office block uses depths 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.
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 1500 m2 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.||**||