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| Winding elegantly upwards with PERI climbing formwork  With the building´s structure elegantly wrapped in a cloak-like glass facade, the Al Hamra Tower on the Persian Gulf creates the vision of a highly visible sculpture, rising to an impressive height of 412 metres. As construction progress steadily continues, it becomes clear that the Al Hamra Tower is not only a multi-storey building with a remarkable height but also that a new landmark is being developed through its very distinctive design. After completion in 2010, a total of 98,000 square metres of business and office space will be available on the 77 generously-dimensioned floors. Designed by one of the world´s renowned and leading designers – the American team of architects Skidmore, Owings and Merrill LLP (SOM) – an office building is being constructed which features a subtle hint of luxury together with breathtaking views.The actual ground plan of the building resembles a round-cornered square with 60-metre long edges – with a centrically-arranged core for the elevator and staircase shafts. Wrapped around this core in a counter-clockwise direction is the building´s structure which creates the impression of a spiral. Up to the 70th floor, the external facade makes a 130-degree turn from west to east which means that no storey is the same. In addition, there is a tapering cross-section from the 70th to 77th floor. On the south-facing side, around a quarter of the offset floor area remains open and it is here that the so-called wing walls are arranged on both sides of the core. Through the turning of the tower, they exhibit twisted surfaces with up to ten-degree inclinations. The realization of the distinctive building structure placed extremely high demands on the formwork technology and the Ahmadiah construction team. For this project, experienced engineers of the Weissenhorn-based formwork and scaffolding specialist, PERI, combined different climbing formwork systems as well as SKYDECK slab formwork to form a comprehensive customised solution. The formwork planners created detailed construction drawings for each of the 77 different floors and developed an integrated and uniform formwork concept. This has ensured that any adjustments required for the respective section has been kept to a minimum and each individual floor has been completed in only eight days. The internally-positioned core walls are constructed in advance with the help of PERI ACS self-climbing technology. From the modular-designed construction kit with five possible climbing variants, working platforms and other platforms have been formed which move reliably upwards from floor-to-floor by means of the ACS climbing unit without requiring a crane and regardless of weather conditions. The ACS can also be combined with the contractor´s own TRIO panel formwork without any problems – an important advantage for the contractor. All ACS versions work smoothly with each other and can be extended at any time using a range of additional construction kit components. With protection being provided by the PERI RCS climbing protection panel, floors and edge beams can be safely and efficiently constructed. Thus, site personnel in the top three floors under construction are constantly protected against falling and the effects of strong winds at large heights. Slab shoes are used for anchoring to the building itself and guide the RCS climbing rails when moving to the next concreting section. Moreover, this means that the complete scaffolding unit is connected to the structure during the climbing procedure. The Al Hamra project team also decided to operate the climbing protection panel without any crane support. In order that the planned eight-day cycle can also be maintained for the floor areas, the construction site team has formed the close to 1,500 m˛ slab areas using the PERI SKYDECK system under the protection of the RCS enclosure. The lightweight aluminium elements allow simple, fatigue-free and fast assembly. In addition, early striking can take place due to the SKYDECK drop head system. The main beams and panels are thus quickly available for the next cycle – with the temporary supports remaining in position. This reduces on-site material requirements and accelerates construction progress. The spiral form of the building not only results in different-sized floor areas but also means that the southern core external walls as well as the wing walls undergo a change in position and length. To deal with this, climbing units were formed with elements from the PERI SKS single-sided formwork climbing system and VARIO girder wall formwork. On the one hand, this solution is being used for single-sided climbing with massive structural components whilst, on the other, the up to ten-degree forward and reversed-inclined retention walls on the Al Hamra Tower can also be concreted. Without requiring any special measures, additional concrete loads or lifting forces can be safely transferred into the building. The twisted form of the wall surfaces caused by the turn can be very accurately adjusted and realized with the VARIO wall formwork elements. With a special crane pick-up spreader comprised of PERI system components, the site crew can suspend the SKS/VARIO moving units on the crane certain in the balance point. From the outset, all climbing variants were designed so that both the standard storey heights of 4.20 metres as well as the up to 11-metre high intermediate floors can be completed without any time-consuming and costly modification work being required. The different positioning of the window box-outs could also be allowed for with the PERI systems along with handling unexpected adjustments to the construction sequence due to changes in construction site conditions. write your comments about the article :: © 2008 Construction News :: home page |