Steel Buildings in Europe

Part 5: Detailed Design of Trusses 5 - 14 diagonals in compression under gravity loads (in red in the diagram above); the posts are single angles 100  100  10. Note that, in the central panels, secondary diagonals and posts are present. They would generally be installed with one or other of the following objectives:  To permit application of a point load between main nodes, without causing further bending in the upper chord  To reduce buckling, in the plane of the truss of central members of the upper chord. In this example, the secondary trusses reduce the buckling length. The pairs of angles which make up the section of a diagonal are joined by battens, to ensure combined action with respect to buckling between the truss nodes. To be efficient, battens must therefore prevent local slip of one angle in relation to the other. See Section 4.1.3 for more information. Each chord is fabricated in two pieces (see Figure 3.6). The diagonals and posts are bolted at their two ends to vertical gusset plates, which are themselves welded to the horizontal webs of the IPE 330 chords. Detailed diagrams of this type of connection are given in Appendix A and in Sections 5.2 and 5.3. The columns on which the truss is supported are IPE 450, for which the web is perpendicular to the plane of the truss beam. In order to illustrate all of the topics here, the truss beam in the worked example is designed for two situations: a gravity load case and an uplift load case. The loads correspond to the combination of actions, determined according to EN 1990 for verification with respect to the ultimate limit state (ULS). 91 kN 136 kN 182 kN 182 kN 182 kN 136 kN 91 kN ULS combination n°1: Gravity loading (without self-weight) 43,50 kN 65,25 kN 87 kN 87 kN 87 kN 65,25 kN 43,50 kN ULS combination n°2: Uplift loading Figure 2.4 Worked example – Load Combinations