Steel Buildings in Europe

Part 2: Concept Design 2 - 28 3.5.3 Bases A typical pinned base is shown in Figure 3.14. The base plate is generally at least as thick as the flange of the column. Most authorities accept that even with four holding down bolts as shown in Figure 3.14, the base is still pinned. Alternatively, the base may have only two holding down bolts, on the axis of the column, but this may make the erection of the steelwork more difficult. Columns are normally located on a number of steel packs, to ensure the steelwork is at the correct level, and the gap between the foundation and the steelwork filled with cementicious grout. Large bases should be provided with an air hole to facilitate complete grouting. Holding down bolts are generally embedded in the foundation, with some freedom of lateral movement (tubes or cones) so that the steelwork can be aligned precisely. The holes in the base plate are usually 6 mm larger than the bolt diameter, to facilitate some lateral alignment. ~ 5 4 3 2 1 1 Holding down bolts 2 Base plate 3 Grout 4 Tube (or cone) 5 Anchor plate Figure 3.14 Typical portal base detail 3.5.4 Bracing Connections Forces in portal frame bracing are generally modest. Typical connections are shown in Figure 3.15. Gusset plates should be supported on two edges, if possible.