Steel Buildings in Europe

Part 4: Detailed Design of Portal Frames 4 - 39 restraint. The column section may need to be increased if intermediate restraints cannot be provided. Restraint may be provided by stays to the inside flange, as shown in Figure 8.2 shows stiffeners in the column, which are only typical at the level of the underside of the haunch where they act as compression stiffeners. At other locations, stiffeners are generally not required. 2 1 1 Side rail 2 Column Figure 8.2 Typical eaves detail using a column stay At the underside of the haunch level, it may be convenient to provide a hot- rolled member, typically a hollow section, to provide restraint. It is essential to connect the bracing on the inner flange to the outer flange at some point in the length of the building. 2 1 1 Cold rolled member supporting the cladding and gutter 2 Circular hollow section Figure 8.3 Typical eaves detail using a circular hollow section as a longitudinal bracing member Figure 8.4 shows a typical moment distribution for permanent and variable actions and indicates the positions of restraints on a typical column. The presence of a plastic hinge will depend on loading, geometry and choice of column and rafter sections. In a similar way to the rafter, both out-of-plane and in-plane stability must be verified.