Roof Purlin Design Example

Design guide for cold formed steel purlin roof framing systems.

Roof purlin design example.

This spread sheet can only be used for load combinations with two variables. Design of roof purlins. 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. Design of purlin solved problem by prof l agarwal.

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 traditional timber truss construction purlins rest on the principal rafters of the truss. The four steps in the general methodology of the component stiffness method are presented. 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. A common arrangement is a rafter and purlin system which combines purlins and rafters. This spreadsheet is to be used to check the adequacy of roof purlins for a specified combination of loads. They are often used for structural support in walls and as floor joists in addition to roofs.

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. The designis based on the maximum yeild strength mn fysx as stated in the aisc manual 13th ed. First the development of forces requiring anchorage in purlin roof systems is discussed. 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.

Its shape allows the purlin to overlap with others at the joints.