The secondary steel structures refer to the secondary components or functional components of steel structure except main stress components such as beams and columns. Generally the secondary steel structures include purlin, tie rod, angle support, tie bar, sleeve pipe, roof bracing and column bracing. Now let’s follow the editor to find out more details of these components.
Purlins can be divided into roof purlins and wall purlins according to the position. "Roof purlin refers to roof framing members that span parallel to the building eave, and support the roof decking or sheeting." Wall purlin refers to wall framing parts that parallel to steel columns, and support the wall cladding panels. According to the shape, purlins can be divided into C shape and Z shape. Z shape purlin will be the better choice for roof with large slope. And C shape purlin will be generally used in a normal steel building.
Picture 2- C Purlin
Picture 3- Z Purlin
The main function of tie bars should be axial force transmitting (such as wind load), combined with cross horizontal support, cross column support or longitudinal rigid frame column support, to form a stable longitudinal support system, which increases the lateral stability of beams and columns. The tie bar is a fixed connecting rod between the steel beams, generally expressed as XG or GXG on the drawings, and its function is to connect each door frame. Tie bars are generally made of steel pipes with high strength and lightweight material.
Picture 4- Tie Bar
Angle steel can be composed of various stress-bearing components according to different needs of the structure, and can also be used as a connection part between components. Angle steel is a carbon structural steel with a simple section for construction. It is mainly used for metal components and factory buildings. Angle support requires good weldability, plastic deformation performance and certain mechanical strength. Angle steel, commonly known as angle iron, is a long strip of steel whose two sides are perpendicular to each other. There are equilateral angles and unequal angles.
Picture 5 - Angle Support
Tie rod is a fixed connecting bar between the purlins. There are straight tie rod and diagonal tie rod. They are generally expressed as ZLT and XLT on the drawings, and normally use round steel with a diameter of 12mm, which is used to connect the entire roof purlin into a whole. The tie rod is a support point of the out plane of purlin, so the tension on the rod is the horizontal load on purlin. The diagonal rod, the purlin and the struts form a geometrically invariable system, which supports the direction of weak axis of purlin and prevents the purlin from deforming on the weak axis.
Picture 5 - Tie Rod
Sleeve pipe is also called the round tube. It is mainly used for supporting. It is generally expressed as CG on the drawing, ∅12 round steel or ∅32x2.0 round pipe.
Picture 6 - Sleeve Pipe
The horizontal support between the roof frames forms a rigid structure to enhance the overall rigidity of the roof, so as to ensure the lateral stability of the upper chord or the upper flange of roof beam, and at the same time transmit the wind force from the wind resistance column to the longitudinal column top. The main functions of roof support including ensuring the overall space of the structure, avoid the lateral instability of compression rod and prevent the tension rod from generating excessive vibration, bear and transmit the horizontal load, ensure the stability and convenience of the structure installation.
Picture 7 - Roof Bracing
Column bracing is a connecting rod or angle steel set between two adjacent columns to ensure the overall stability of the building, improve the lateral stiffness and transmit the longitudinal horizontal force. The column bracings are connected with columns to form a stable longitudinal frame to guarantee the longitudinal rigidity of the steel structure factory building. The inter-column bracings bear the longitudinal force and the wind load from the end gables, also the longitudinal braking force of the crane needs to be transmitted to the foundation through column bracings.
Picture 8 - Column Bracing
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