New equipment goes to work on JBR Sector Six

Sector 6 of the Jumeirah beach Residence (JBR) project is very different to other contracts on the project. It features a massive 16 000 m² podium area over the entire project site, rather than individual podium levels for each tower. Construction Week visited the site.

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By  Colin Foreman Published  January 8, 2005

New equipment goes to work on JBR Sector Six|~|54 Proj Body.jpg|~||~|In winning Sector 6 of the Jumeirah Beach Residence (JBR) project, main contractor Al Shafar General Contracting Co. has purpose-ordered a variety of new equipment to meet the tight contract period. The project also features a massive 16 000 m², four storey high podium, with new formwork systems from Doka, and new passenger/material hoists from Alimak. It is believed to be only the second project in the region to use the recently introduced Liebherr luffing jibs 112HC-L cranes. Jumeirah Beach Residence is a massive 2.2 million m² gross floor development along a 1.7 km beach frontage area in Jumeirah, situated on the shore side of the Dubai marina. It includes a total of seven construction packages to provide 36 residential high-rise towers, four hotels and beach clubs to cater for a community of 25 000 people. Al Shafar’s Sector 6 contract features four high-rise towers with varying heights between 107-172 m plus a 120 m high building linking two of the towers. The podium level is different to the other sectors in that it is a ‘stand alone’ podium and will be connected by a series of bridges to the other podiums. Al Shafar started work on Sector 6 in March 2004 with concrete pours for the raft foundation. “The depth of the raft for the tower ‘foot print’ is approximately 2.8 m and 1.4 m for the general raft across the remainder of the site.” explained project manager, Ehab Edward Narouze. “For each tower’s raft, approximately 5000 m3 of concrete was poured.” Once the raft was complete, the contractor, using the Doka Top50 climbing formwork system, started work on the tower’s core shafts, working two levels ahead of the slab on each tower. The common podium across the site features a basement, grade level, a mezzanine, a plaza and upper plaza, with the lower three levels to be used for parking and the two plaza levels for retail outlets. Featuring a variety of heights between 3.50-3.75 m in the podium levels, with non-typical floors and different slab design and thickness, meant that the contractor achieved an 8-12 day cycle, using Dokaflex tables for the slab construction. Once clear of the podium and working on each tower, Al Shafar has been able to achieve a reduced slab cycle of 7-8 days depending on the floor being cast and 6-7 days for the core shafts. Typical floor heights of 3.4 m are being poured using the Doka Top 50 system. Comprising just three components — timber formwork beams, steel whalings and formwork sheets, the system is proving ideal for the project since all parts are reusable and can be optimised for most shapes and sizes. The system is also being used for the core shaft walls and includes telescopic shaft beams and Doka type 150F climbing brackets. For slab construction throughout the Sector 6 contract, Al Shafar has opted for the proven Dokaflex tables system. As ready assembled tables, the system can be shifted in one piece to the next position without being dismantled. With fewer separate parts, formwork erection and striking are greatly accelerated, ensuring the shortest possible forming times for large areas of floor. By mid-November, the contractor had reached level 10 on two towers, level 6 on a third and level 3 on the fourth. Throughout construction, safety is of prime importance to Al Shafar with Doka providing climbing scaffolds and platforms to ensure that all formwork, steelwork, cleaning and casting is done in a protected and safe environment, allowing the labourers to work with enhanced productivity. Al Shafar opted for two new Liebherr luffing jib cranes on Tower 1 of the projects four high-rise towers and link. The two Liebherr 112HC-L luffing jib cranes were purpose-ordered through local distributor INMA, for use on only the second project in the UAE to feature the crane. Previously the first two units had been installed on Dubai’s fourth tallest tower, the 269 m high 21st Century Tower in Sheik Zayed Road for the Al Rostamani Pegel — Arabtec Joint Venture. On the JBR project both Liebherr 112HC-L luffing jib cranes feature a under-hook height of 240 m. The cranes have been designed for work on exceptionally tall buildings or on sites with restricted space. With the steep luffing jib angle (15°-70°) these cranes are able to avoid on-site obstructions with other working areas and slew through 360° under load at only 7 m slewing radius. Featuring a compact slewing radius, the 112HC-L’s are ideal where several cranes have an overlapping slewing radii. Both cranes are climbing with the building’s concrete pouring cycle, with one floor being completed every 6-7 days. The cranes are ‘jacked-up’ to remain on the upper construction level, floor climbing within the building’s core-shaft to the final height of the tower. According to Project Manager, Ehab Edward Narouze, Al Shafar opted for the luffing jibs because of the limited space on Tower 1, even though it occupies the biggest area. “It is also close to the road and cannot therefore swing across the road since it would interfere with the other sectors,” he said. Craneage duties on the remainder of Al Shafar’s Sector 6 project is provided by six Liebherr 8 t capacity tower cranes. The project also features two 44-storey towers and a 26-storey tower linked together by a 40-storey building. All four towers and the ‘link’ building feature a 4-storey podium and final heights vary between 107-172 m. To ensure fast and efficient movement of the labour force and materials for the four tower and link high rise development, Al Shafar purpose ordered six Twin Cage Alimak Scando FC24/32TD passenger/materials, once again through local distributor INMA. The installation of the twin car Alimak hoists have increased its efficiency of passenger movement on each of the towers and also relieves the tower cranes for some of the materials. The Scando FC24/32TD with three motors features a 2400 kg capacity and can travel at a speed of 0-57 m/min for a lifting height of up to 150 m. Car dimensions are 1.5 m x 3.2 m x 2.15 m. The project, on completion, will contain 770 apartments with a mix of one, two, three and four bedrooms with penthouses and loft houses on the upper floors. There will be 20 different types of flat.||**||

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