Purlins Roof Design

Stratco purlins and girts are used to support roof and wall sheeting in industrial commercial and rural buildings and as structural framing in medium sized buildings and relocatable accommodation as well as garages patios and carports.

Purlins roof design. How to design c purlins and sag rods design according to nscp 2015 c purlinsare horizontal type steel section that are used to support the load from the roof deck or the sheathing. 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. Butted purlins are also useful for frames which have large clear spans and where large frame deflections may be harmful to continuous purlin systems. Description this spreadsheet is to be used to check the adequacy of roof purlins for a specified combination of loads.

Various types of roof trusses include king post truss scissor truss north light truss etc. The designis based on the maximum yeild strength mn fysx as stated in the aisc manual 13th ed. This spread sheet can only be used for load combinations with two variables. Purlins are 2 by 4 feet and are installed much like metal roofing.

Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. 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. The shape of cee purlins does not allow end lapping they are butted together. Maximum span is 11 4m.

Purpose use cee purlins are secondary steel framing members most commonly used as roof purlins wall girts and header jamb and sill for windows and doors on metal buildings. In structural steel or aluminum construction purlins usually w shapes or channels transfer roof loads to the major structural elements supporting the roof. Butted purlins can be used over supports or within the depth of the supporting section. Metal roof purlins are installed horizontally under metal roofs.

A common arrangement is a rafter and purlin system which combines purlins and rafters. The plane surface of c purlin on its one side has made it a preferred material for cladding due to its easy installation on concrete structures or steel. Designing of roof trusses as per is 800 and is 875 part 1 2 and 3. The type and spacing of purlins is a design consideration which depends upon the incident roof loads as well as the limiting lengths of sheeting to be used.

Welded together they can be used as columns braces and ties.