TABLE OF CONTENTS The third type of secondary structural members, after purlins and girts, is the eave strut. This unique structural element is located at the intersection of the roof and the exterior wall, so that it acts as both the first purlin and the last (highest) girt. The building s eave height is measured to the top of this member.
The term strut refers to another important function of this element: it typically serves as a compression member in the wall cross-bracing assembly and as a tie between such bracing assemblies located along the same wall. Accordingly, eave struts are often designed for the combined effects of flexure and axial compression. Because of their importance in metal building systems, eave struts have already been mentioned many times in this book.
The traditional shape of eave struts is a channel-like section of Fig. 5.1, which allows the roofing to be attached to the top flange of the member and siding to its web. Some manufacturers produce unique shapes, such as the one shown in Fig. 5.54. Others manage not to have a structural member at the eave at all the first purlin and the highest girt are separate members (Fig. 5.55)!
Depending on the magnitude of the web crippling stresses, the channel-like eave strut can be simply bolted to the top of the primary frame rafter (Fig. 5.56a) or be...
