Steel Buildings in Europe

Part 5: Detailed Design of Trusses 5 - 13 1 2 1 Main truss 2 Purlin truss Note: the horizontal bracing is not displayed in this diagram but it is designed in such a way that the purlins provide efficient lateral restraints to the main trusses. Figure 2.2 Worked example - General layout of the roof The roof is a symmetrical pitched roof; the slope on each side is 3%. Each main truss has a span of 45,60 m and is simply supported at the tops of the columns (there is no moment transmission between the truss and the column). General transverse stability of the building is provided by fixity of the columns at ground level; longitudinal stability is provided by a system of roof bracings and braced bays in the walls. 1 2 5 6 4 3 7 1 2 4 1 Upper chord IPE 330 with horizontal web 2 Lower chord IPE 330 with horizontal web 3 Post - Single angle L100x100x10 4 Top of the column (IPE 450) 5 Diagonals - Double angle 6 Secondary truss members 7 Sketch of the cross-section Figure 2.3 Worked example – View of truss The truss is illustrated in Figure 2.3. The truss chords are parallel and are made up of IPE 330 profiles with the webs horizontal. The diagonals are made of twinned angles: two 120  120  12 angles for diagonals in tension under gravity loads (in blue in the diagram above), two 150  150  15 angles for