Nemetschek Engineering User Contest 2009 • Category 2: CAE Housing & Buildings 75 2 occur. Apart from prestressing, reinforced steel was implemented as well. The design was composed and calculated three-dimensionally, using Scia Engineer. The 3D-computational model was principally used to analyse occurring deformations during the construction and post-construction phase. By including different levels of concrete rigidity, as well as different load sequences, the possible deformations were determined. The different levels of rigidity were determined with Scia Engineer-concrete section, using M-N-Kappa diagrams that included the variable degrees of creep deformation. Because of the eccentricity of the resulting load on the foundation, the building is likely to ‘tilt’. This eccentric load is intercepted by the foundation. The foundation poles are implemented with a specific spring rigidity, in order to cope with the cantilever’s deformation. Because of the large cantilevers, the calculated deformations are relatively large. That is why the building is ‘curved’ upward, using an arch, which ensures the subsidence to reach standard level after the construction phase. The prestressing was executed as a load case, and the position as straight eccentric cable offset. Execution During the execution, it is of great importance to control the subsidence. The form work construction, which has to be assessed higher because of the subsidence, has been determined by using a special arch plan. The temporary creep support will only remain on the cantilevered heads. They are regularly loosened, to jolt the building, and are twisted shut after that. That way, the building can experience controlled subsidence. To see whether the subsidence levels reach prior calculations, they are to be monitored in pre-determined building phases. The largest subsidence is to be expected during the construction phase. The steel framework of the superstructure is linked, during the concluding phase, to the hollow core slabs, which are constructed in the form of a disc. The superstructure deformations, due to the cantilever subsidence, are to be kept at a minimum during the execution. Bolt connections are therefore left loose wherever possible, and the hollow core slab joints and -clefts are filled at the latest possible moment, to increase rotation capacity. The columns, too, are initially placed with a slight deviation, to make sure they end up standing straight. During the eccentric prestressing, there is a considerable risk of unwanted crack formation in the visible part of the profiled concrete. To prevent this, stainless steel slabs are placed, serving as crack initiators. The massive pylons have a large concrete volume; crack-restraining reinforcement is to prevent the formation of too large shrinkage cracks. Aircraft carrier as Pon head office
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