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Many steel building structures are supported by purlins, so what is purlin?

1、 What is purlin

Purlin refers to the roof beam vertically on the roof truss, or located in the horizontal position of the rafters, rafters or roofing material to support the important member. Purlins generally have two types, one is called the main purlin, the other is called secondary purlin, the specific installation location will be different.

2、 Principles for installing roof purlins

1)When the purlin span is less than or equal to 4 meters, it should be determined whether the roof position needs to be installed according to the calculation requirements. When the roof slope is greater than or equal to 1/10, or when the purlin span is greater than 4 meters, it is necessary to install a brace at the mid-span position of the purlin and at the edge of the compressed wing. When the purlin span is more than 6 meters, it is better to install a brace at the three points of the purlin.

2)If there is a skylight on the roof, it is necessary to install a straight brace and a diagonal brace between the purlins on both sides of the skylight, and also install a diagonal brace at the position of the brace, so that the component of the purlin along the roof slope direction is transmitted to the steel column or steel beam.

3)When installing the sag rod, the sag rod should generally be installed at a position about one-third of the height from the purlin flange. When the purlin is subject to wind suction and the force is negative, and the plane stability does not meet the requirements, a scissor-type tie bar needs to be installed at a position one-third of the height of the upper and lower purlin flange.