Steel Buildings in Europe

Part 8: Building Envelope 8 - 25 sections as defined in EN 1993-1-3 [11] , hence section properties will be need to be based on effective values (reduced gross properties). Further information on these sections may be obtained from the manufacturers’ technical literature. 1 2 3 4 1 Zed 2 Ultrazed 3 Zeta 4 Sigma Figure 4.2 Common types of purlin 4.1.2 Purlin and side rail layout options Most manufacturers produce guidance on typical purlin layouts that are efficient for various situations. These layouts are governed by such aspects as maximum purlin length (generally not more than 16 m for transport and site access reasons) and the ability to provide semi continuity by the use of sleeves or overlaps for maximum efficiency. The most commonly used layouts are shown in Figure 4.3 to Figure 4.7. Specifiers seeking further information on when and how to use a particular layout should consult the purlin manufacturers for detailed information relating to their specific systems. In any event, the purlin manufacturer should be consulted before the layout is finalised. Single-span lengths - sleeved system In sleeved systems, each purlin is the length of a single span but sleeves are provided at alternate supports so that each purlin is effectively continuous across two spans (Figure 4.3). At the penultimate support, sleeves are provided at each purlin, to provide semi continuity and additional strength in the end bay. This system is considered to be the most efficient for buildings with bay centres between 5 m and 7 m. Heavier sections can be provided in the end bay if necessary. 1 2 3 4 1 Sleeved purlin 2 Penultimate support 3 Raf t er 4 Sleeve Figure 4.3 Single-span lengths – sleeved system