Purlins in the Form of Cross-section


1. Cross section of the real purlin


The application of solid-type cold-formed thin-walled steel structure sections in engineering is common. Among them, the curling channel (also known as C-shaped steel) purlins apply to the roof slope i ≤1/3 of the situation.

A. Straight and oblique z-shaped purlins are suitable for roof conditions i> 1/3. Oblique curling Z-shaped steel can be stacked when stacked, small footprint. Made of continuous beam purlins, the structure is also very simple.


2. Purlin load and load combination

A. 1.2 ×permanent load + 1.4 ×max {roof uniform live load, snow load};

B. 1.2 ×permanent load + 1.4 ×construction maintenance concentrated load conversion value.

When considering the effect of wind suction on the stress of the roofed steel plate, the following combinations of loads are also required:

C. 1.0 ×permanent load + 1.4 ×wind suction load.

Analysis of internal force of purlins

D. The purlins arranged on the skew beams of the frame are curved in the direction of the two centroids along the cross-section under the uniform load perpendicular to the ground and belong to the two-way bending members (which are different from the general bending members).

E. In the analysis of internal force, we must first decompose the load into the load component qx, qy along the direction of the main axis of the section.

F. C-type purlins in the load under the calculation of the following diagram: