What is the purpose of sag rods?

What is the purpose of sag rods?

(in a roof) a rod for preventing the sagging of an open-web steel joist that is used as a purlin with its depth at right angles to a roof slope.

Why sag rods are used with purlins?

Mainly sag rods are provided to give the lateral stability to the purlin and also to break the slenderness length of the purlin member. By providing the sag rod you can optimise the purlin sizes.

What is anti sag rod?

Metsec round lok anti-sag rods and lateral support angles are designed to restrain purlins against twist under wind uplift conditions and contribute support during sheeting. In all other cases where an anti-sag system is required, Metsec tubular sag rods and apex ties are to be used. …

What are sag bars?

Sag bars are used to restrain the bottom flange of a purlin in order to reduce its effective length when exposed to uplift conditions. Where download is critical, with a relatively small uplift the sag bars contribute very little to the structural integrity of the roof.

What is AZ purlin?

Z purlins resemble the shape of a letter “Z” and are also referred to as Zee or Zed purlins. They are roof framing members that span parallel to the building eave and support the roof decking or sheeting. The metal purlins are in turn supported by rafters or walls.

What is the maximum bending moment for purlin?

800
The maximum bending moment for design of purlins can be taken as. WL/6.

What is the purpose of a under purlin?

In a conventional roof frame the underpurlins support the underside of the rafters. This allows for the most economic rafter size and prevents the roof from sagging and collapsing. Underpurlins must be in single lengths where possible. They must be in straight runs at right angles to the direction of rafters.

What is the difference between purlins and Girts?

Purlins are specific to the roof. In the shape of a “Z”, a purlin is a horizontal structural member that supports roof covering and carries loads to the primary frame. Also, in the shape of a “Z”, a girt is a horizontal structural member that is attached to sidewall or end wall columns and supports paneling.

What are Z beams used for?

Z purlins, also called Zee Purlins, are horizontal beams that form the roof and wall joists of a building shell structure. The name comes from resembling the letter Z. The shape of the purlins helps in overlapping the joint which makes it stronger and studier than C purlins.

How Far Can C purlins span?

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.