Steel Buildings in Europe

Part 4: Detailed Design of Portal Frames 4 - 45 2 1 1 1 Moment-resisting frames 2 Position of plan bracing Figure 9.6 Individual, local sway frames 1 1 2 2 2 2 3 1 Moment connection 2 Pin connection 3 Eaves strut Figure 9.7 Hybrid frame along the full length of the building In design of both systems, it is suggested that:  The bending resistance of the portalised bay (not the main portal frame) is checked using an elastic frame analysis  Deflection under the equivalent horizontal forces is restricted to h /1000.  The stiffness is assured by restricting serviceability deflections to a maximum of h /360, where h is the height of the portalised bay. In some cases, it is possible to provide conventional bracing on one elevation, and provide moment resisting frames on the other. The effects of racking action due to the difference in stiffness of the sides is generally negligible due to the diaphragm action of the roof.