Steel Buildings in Europe

Part 5: Detailed Design of Trusses 5 - 2 For the longitudinal stability of the structure, a transverse roof wind girder, together with bracing in the side walls, is used. In this arrangement the forces due to longitudinal wind loads are transferred from the gables to the side walls and then to the foundations. Lateral stability provided by portal trusses Longitudinal stability provided by transverse wind girder and vertical cross bracings (blue) No longitudinal wind girder Figure 1.2 Portal frame a arrangement In the second case, as shown in Figure 1.3, each vertical truss and the two columns on which it spans constitute a simple beam structure: the connection between the truss and a column does not resist the global bending moment, and the two column bases are pinned. Transverse restraint is necessary at the top level of the simple structure; it is achieved by means of a longitudinal wind girder carries the transverse forces due to wind on the side walls to the braced gable walls.