Roof Purlin Design Example

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.

Roof purlin design example.

Design of purlin solved problem by prof l agarwal. They are often used for structural support in walls and as floor joists in addition to roofs. 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. The four steps in the general methodology of the component stiffness method are presented.

This spreadsheet is to be used to check the adequacy of roof purlins for a specified combination of loads. Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. Roof purlin design roof purlin design. In traditional timber truss construction purlins rest on the principal rafters of the truss.

The designis based on the maximum yeild strength mn fysx as stated in the aisc manual 13th ed. 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. Its shape allows the purlin to overlap with others at the joints. Z purlin the zee or z purlin is shaped like a letter z.

C purlin cee or c purlins are shaped like a squared off letter c. First the development of forces requiring anchorage in purlin roof systems is discussed. A common arrangement is a rafter and purlin system which combines purlins and rafters. This spread sheet can only be used for load combinations with two variables.

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.