Roof Purlin Design Example

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

Roof purlin design example.

Design guide for cold formed steel purlin roof framing systems. Design of purlin solved problem by prof l agarwal. C purlin cee or c purlins are shaped like a squared off letter c. Design of roof purlins.

They are often used for structural support in walls and as floor joists in addition to roofs. Its shape allows the purlin to overlap with others at the joints. Forces in roof systems as presented in chapter 5 of the new aisi. 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.

Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. 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. This spreadsheet is to be used to check the adequacy of roof purlins for a specified combination of loads. 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.

This spread sheet can only be used for load combinations with two variables. 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. Roof purlin design roof purlin design.

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