Table of Contents
- 1 How is purlin designed?
- 2 How do you choose purlin spacing?
- 3 What kind of member is purlin?
- 4 What is the maximum spacing for purlins?
- 5 How do we reduce the resultant deflection of purlin?
- 6 What is the length of a purlin section?
- 7 How strong should a purlin roof be?
- 8 What are the different types of load on a purlins?
How is purlin designed?
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. …
How do you choose purlin spacing?
The spacing of purlins depends largely on the maximum safe span of the roof covering and glazing sheets. Hence, they should be less than or equal to their safe spans when they are directly placed on purlins.
How do you size a purlin?
Single Span System: One purlin spans the length of the structure….The sizes are as follows:
- A four-inch purlin can span 12 feet.
- A six-inch purlin can span 18 feet.
- An eight-inch purlin can span 25 feet.
- A ten-inch purlin can span 30 feet.
What kind of member is purlin?
A purlin (or historically purline, purloyne, purling, perling) is a longitudinal, horizontal, structural member in a roof. In traditional timber framing there are three basic types of purlin: purlin plate, principal purlin, and common purlin.
What is the maximum spacing for purlins?
2308.7. The maximum span of 2-inch by 4-inch (51 mm by 102 mm) purlins shall be 4 feet (1219 mm). The maximum span of the 2-inch by 6-inch (51 mm by 152 mm) purlin shall be 6 feet (1829 mm), but the purlin shall not be smaller than the supported rafter.
Which section is best suited for purlin design?
Channels, angle sections, and old formed Z-sections are widely used as purlins. Explanation: Theoretically, it is desirable to place purlins only at panel points. They are placed at panel points to avoid bending in the top chords of roof trusses.
How do we reduce the resultant deflection of purlin?
Purlins with clip-fastened sheeting can be designed by putting the value of the sheeting restraint factor kry equal to zero. Purlins with clip-fastened sheeting should have one or more rows of bridging which prevent lateral deflection and twisting of the cross-section.
What is the length of a purlin section?
Well that depends upon the Span you choose for your Purlin sections. Normally available section lengths are 6m or 9m . Based on design and serviciability requirement and Framing requirements , purlin span is approx 3m or 3.5m. The Span can be further modified by adjusting the purlin spacing to reduce or increase the influence load on the Purlin.
How to design steel purlin sections using cold formed sections?
This post will be focusing on design of steel purlin using cold formed sections. By default, purlin sections assume the slope of the roof they are supporting. The spacing of purlins usually call for careful arrangement, in the sense that it should follow the nodal pattern of the supporting trusses.
How strong should a purlin roof be?
Therefore, a purlin should be adequately strong to withstand the loads it will encounter during its design life, and should not sag in an obvious manner thereby giving the roof sheeting an undulating and/or unpleasant appearance. This post will be focusing on design of steel purlin using cold formed sections.
What are the different types of load on a purlins?
In their design life, purlins are subjected to dead load (e.g self weight of sheeting materials and accessories), live load (e.g. during maintenance services and repairs), and environmental loads (e.g. wind and snow load).