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Commercial Industrial The lateral stability of large industrial buildings Richard Henderson discusses the lateral stability of large industrial buildings such as the Siemens Turbine Blade Factory 20 NSC July/Aug 16 Caunton Engineering had up to five mobile cranes working on its steel programme, with multiple spans of the building being erected at any one time. The facility also features an attached two-storey office block that is structurally independent and gains its stability not from bracing but from a series of moment frames. It features a steel frame supporting precast planks on the beams’ bottom flange - a construction method chosen as the client wanted exposed soffits. The first wind farm to receive turbines from the Hull facility later this year is expected to be Dudgeon, which is located off the Norfolk coast. 19 The (northern) manufacturing area of the Siemens factory has four bays with two 40t electric overhead travelling (EOT) cranes travelling on runway beams supported by double lattice columns. This arrangement conveniently allows the runway beam vertical reaction to be transferred to the ground directly through one leg of the double column. The estuary-side site requires piled foundations and this allows overall building stability in the direction perpendicular to the runway beams to be provided by fixed base columns. The double lattice columns are laterally stiff by virtue of acting as the tension and compression booms of a vertical cantilever truss. The push-pull in the columns is transferred via pile caps into the piles. The column leg not supporting the crane runway beams continues upward to support the roof trusses which are simply supported between columns. In the orthogonal direction, K bracing is provided to stabilize the building. The lower (southern) finishing area of the building is separated from the manufacturing area by a movement joint. No EOT cranes are required so double columns are not provided. UB columns are adopted and lateral stability is provided by vertical bracing in the three perimeter walls. Bracing is also provided where the finishing area abuts the manufacturing area. The roof is braced in plane so the building forms a braced box. For a structure on a site where piles are not necessary, fixed-foot columns are more difficult to achieve because of the flexibility of pad foundations. In these circumstances it may be appropriate to design the columns to have pinned feet and frame into the roof trusses such that the columns and roof trusses form portal frames with a stiff truss rafter. The column stiffness therefore controls the sway deflection. A space free from bracing can be achieved if there is a regular array of columns in each direction and the lateral stiffness is similar in each of the orthogonal directions. A conventional portal frame structure is similarly designed as continuous in the plane of the frame and achieves stability through the moment connections between columns and rafters. The portal frame rafters are more flexible than the truss rafters and therefore contribute to the flexibility of the frame. In the orthogonal direction, the portal frames are often braced or portalised bays can be introduced if internal bracing interferes with the building function. These examples show how the choice of stability system of the building is driven by the type of foundation, the use of the enclosed space and the opportunity for the use of bracing. The four-span manufacturing area was the first part to be erected


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