Roof Purlin Design Example

In traditional timber truss construction purlins rest on the principal rafters of the truss.

Roof purlin design example.

First the development of forces requiring anchorage in purlin roof systems is discussed. Its shape allows the purlin to overlap with others at the joints. C purlin cee or c purlins are shaped like a squared off letter c. The four steps in the general methodology of the component stiffness method are presented.

Design guide for cold formed steel purlin roof framing systems. This spread sheet can only be used for load combinations with two variables. They are often used for structural support in walls and as floor joists in addition to roofs. Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel.

A common arrangement is a rafter and purlin system which combines purlins and rafters. Design of purlin solved problem by prof l agarwal. The designis based on the maximum yeild strength mn fysx as stated in the aisc manual 13th ed. Design of roof purlins.

Forces in roof systems as presented in chapter 5 of the new aisi. Z purlin the zee or z purlin is shaped like a letter z. The roof support system is a ridgepole and either rafters which run perpendicular from the top of the walls to the ridge or purlins which run parallel to the ridge. In timber construction purlins are nailed to the rafter or supporting trusses while in steel roof construction they are welded or bolted to the rafters or trusses by the means of cleats.

For example an 8 x 4 under purlin would support the center of a row of 6 x 2 rafters that in turn would support 3 x 2 roof purlins to which the roof cladding was fixed.