Roof Purlin Design Example

The four steps in the general methodology of the component stiffness method are presented.

Roof purlin design example.

Z purlin the zee or z purlin is shaped like a letter z. 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. Design guide for cold formed steel purlin roof framing systems. Design of purlin solved problem by prof l agarwal.

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. A common arrangement is a rafter and purlin system which combines purlins and rafters. The designis based on the maximum yeild strength mn fysx as stated in the aisc manual 13th ed. C purlin cee or c purlins are shaped like a squared off letter c.

For example a roof purlin with no transversal element other than sheathing between the extremities on the compressed flange will have an unsupported length equal to its overall length. Roof purlin design roof purlin design. They are often used for structural support in walls and as floor joists in addition to roofs. This spread sheet can only be used for load combinations with two variables.

Forces in roof systems as presented in chapter 5 of the new aisi. In traditional timber truss construction purlins rest on the principal rafters of the truss. 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. Design of roof purlins.

This spreadsheet is to be used to check the adequacy of roof purlins for a specified combination of loads.