Nemetschek Engineering User Contest 2009 • Category 2: CAE Housing & Buildings 47 2 Numbers • Height above ground: 192 m • Total built up area: 71600 m² • Mean area of one typical tower floor: 1200 m² • Quantity of concrete (excluding piles): 34500 m³ • Quantity of steel reinforcement: 6950T • Quantity of steel structure: 50T • Completion time: 33 months (demolition of existing buildings not included) Structural design Model development A complete 3D model of the tower including all slabs, beams, walls, columns, piles and the raft was made with ESA-Prima Win. The details of the model incorporates also all openings in the walls, lintels and slabs with the different type of concrete grades, and the bi-linear springs simulating the soil-structure interaction. Due to the shape of the building, every single floor is different from one another. The construction of the model was made by creating a typical floor corresponding to the envelope of all levels. Then, by representing the façades with shell surfaces and using the intersection tool, the parts falling outside the shells were trimmed off. The size of the general mesh is about 2 m which involves 54000 nodes and is sufficient to simulate the general behaviour of the structure. When detailing the calculating of one level, the mesh is locally refined over this level and the adjacent ones. The graphical representation combined with the various members selection tools of the program where used to verify efficiently the geometry, the loads, the material characteristics of each element and the general behaviour of the model. Particularities of the structural calculation • Calculation of the foundation As mentioned earlier, the soil structure interaction is modelled with bilinear springs applied on the soffit of the raft, along the barrette shafts and on the barrette toes. The results obtained with this modelling were compared with those obtained from a 3D volumetric model and they appeared to be satisfactorily consistent. • General building movement The foundation settlement and the difference of means compression stress between the core walls and the columns implied significant differential vertical displacement between the core of the tower and the perimeter. These movements are reduced, to some extent, by consideration of the construction phasing and creep To ensure that all situations are covered by the calculation, the slabs are calculated considering the envelope of the forces obtained from the general 3D model and from a partial model on fixed supports that can easily be extracted from the general one. • Down load path and load transfer In the lower levels of the building, the architectural arrangement required complex load transfer that are also affected by the general building deformation. Graphical views of the principal stresses were used to better understand the down load path and find structural solutions. • Calculation of the lintels: The lintels above the doors of the bracing walls are modelled as small wall elements including the details of all the openings. The reinforcement is calculated by using the possibility offered by the program to give the resultant forces in sections. In some cases the amount of openings required for the ducting is such that the lintels can not withstand the forces linking the parts of the bracing walls. In these cases, we included steel profiles in the concrete. These profiles could be better modelled with Scia Engineer that we started using during the project design. Therefore, we made local model of the lintels with this last program and applied the displacement obtained from the general model to calculate the profiles. Conclusion The different tools offered by the software contributed to achieve this very large and complex model swiftly, to control and operate it and to make the best use of the calculation results. ZLOTA 44 - 200 m high tower in Warsaw
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