The secondary members shall include Purlins, Girts and eave struts used to support the wall & roof cladding. Secondary members have certain functions. They act as struts that help in resisting part of the longitudinal loads that are applied on the building such as wind & earthquake loads and they provide lateral bracing to the compression flanges of the main frame members thereby increasing frame capacity. Secondary Members are also used as side runners, eave struts, fascia channels, door posts, window posts, rafter stays, column stays, base angles and other miscellaneous structural parts.
Galvanized Iron (G.I) Purlins, Girts and eave struts are cold formed sections and designed in accordance with the �Cold�Formed Steel Design manual� of American Iron and Steel Institute (AISI). Minimum yield strength of G.I secondary members is 34.5 KN/cm� and thickness ranges from 1.5mm to 3.2mm.
Open Web joist is another secondary member; the application of open web joist is as roof secondary member supporting roof sheeting panels and mezzanine joists in multi-storey buildings. It enhances the clear working space while reducing the main members.
Other secondary members are cable bracing, flange bracing, base angles, clips and miscellaneous structural parts.