Steel Buildings in Europe

Part 4: Detailed Design of Portal Frames 4 - 47 opening in the side of the building, additional intermediate bracing will be required in a similar way to that described above. 3 1 2 1 Member restraining plastic hinge at bottom of haunch 2 Eaves level 3 Position of plan bracing Figure 9.10 Typical bracing pattern in building using a hot-rolled member to restrain a plastic hinge at the base of the haunch 9.2.8 Bracing to restrain longitudinal loads from cranes If a crane is directly supported by the frame, the longitudinal surge force will be eccentric to the column, and will tend to cause the column to twist, unless additional restraint is provided. A horizontal truss at the level of the girder top flange or, for lighter cranes, a horizontal member on the inside face of the column flange tied into the vertical bracing may be adequate to provide the necessary restraint. For large horizontal forces, additional bracing should be provided in the plane of the crane girder (Figure 9.11 and Figure 9.12). The criteria given in Table 9.1 were given by Fisher [3] to define the bracing requirements. 3 2 1 4 1 Eaves level 2 Crane girder level 3 Position of plan bracing 4 Bracing for very large crane loads on the inside flange of the column Figure 9.11 Elevation showing position of additional bracing in the plane of the crane girder