Span C Purlin Roof Design

How far can c purlins span.

Span c purlin roof design.

Continuous purlin span are simply supported at each end and at a series of equally spaced intermediate supports. This is slightly smaller than the centre to centre of the rafters. Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. The number of supports beams or purlins affects the allowable span length.

20 95 30 d c a b variable angle 18 x 22 holes 34 x 10 recess upturned lip z sections standard z the following diagrams and tables illustrate the sizes and thicknesses readily available for. In general c purlins sheds are best for smaller spans. Four or more equi spaced supports. Three equi spaced supports equal spans.

Where lapping occurs it is the centre line of the lap. To identify whether yours is the earlier or the latter type look for the end of the rails and check whether the shapes mimics the shape of letter c or letter z. Of a fascia purlin in fascia applications. The c section can be supplied as a standard configuration or with the top flange bent to suit the roof slope.

Purlins near roof edges or changes of roof slope are subject to higher wind forces than interior purlins. Design specification data section z or c thickness mm yield stress mpa mass kg m 75 95 0 95 550 1 26 75 12 1 2 500 1 59 75 15 1 5 450 1 97 100 10 1 0 550 1 77 100 12 1 2 500 2 10 100 15 1 5 450 2 61. Tables are given for 5 or more spans. As per as1684 and as4055 spanman adopts a nett pressure coefficient applied along the full length of the purlin of cpn 2 0 for non cyclonic zones n1 to n6 and cpn 2 5 for cyclonic zones c1 to c4.

Maximum roof slope is 5 for monoslope and 22 5 for pitched roof. Data is given in each table for. Monoslope pitched single. For outwards loads on equal continuous spans the.

Purlin design the basic span is the distance between the bolts that affix the purlins to the cleats. This is right at the limit of a purlin s capacity and does no leave much margin for coping with nasty weather conditions. Two supports one at each end double span. These tables are for spans in which purlins are lapped over each support where the lap length is 15 of the span.

Meanwhile there are two kinds of purlin span for metal roof based on the shapes which are the c purlins and z purlins. This design usually involves a lot of extra bracing. Where purlin spans are unequal between supports each purlin should have 6 25 of each adjacent span added not 6 25 of that purlin s span. Versus the size centers of the purlins bridging and connection details.