The selection of steel supports for scaffolding is a key factor in ensuring the overall stability, safety, and economy of the scaffolding. It is necessary to comprehensively consider various factors such as construction scenarios, load requirements, material properties, and regulatory standards. The following are specific selection criteria:
1、 Based on the construction scenario and engineering characteristics
Engineering type
The strength and stiffness requirements for steel supports vary greatly among different types of buildings, such as building structures, bridges, tunnels, and tall formwork projects. For example, tall formwork supports (such as those with a floor height exceeding 8m and a span exceeding 18m) require high-strength, large-sized steel supports (such as steel pipes with a diameter of over 60mm), while ordinary low rise building scaffolding can use conventional specifications (such as steel pipes with a diameter of 48mm).
Special scenarios (such as cantilever scaffolding, large-span structures, and high-altitude work platforms) require targeted selection. For example, the cantilever part needs to consider the anti pull and anti bending performance of steel supports, and thick pipe walls or customized steel sections need to be selected.
Environment
In humid environments such as basements and rainy season construction, corrosion-resistant steel supports (such as galvanized steel pipes) or anti-corrosion treatment should be used;
The heat/cold resistance of steel should be considered for high and low temperature environments, and materials that are prone to brittleness at extreme temperatures should be avoided;
Steel with good toughness and high yield strength (such as Q355) should be selected in earthquake prone areas to enhance seismic stability.
2、 Calculate parameters according to load requirements
Load type and size
It is necessary to clarify the loads that the scaffold can bear, including dead loads (the weight of the steel support itself, scaffold boards, templates, etc.) and live loads (construction personnel, mechanical equipment, material stacking, etc.), and calculate the total load according to the "Unified Standard for Safety Technology of Construction Scaffolds" (GB51210).
When the load is large (such as in the stacking area or heavy machinery operation), high bearing capacity steel support should be selected, such as increasing the wall thickness of steel pipes (such as 3.6mm thick vs 3.2mm thick), and using socket or bowl buckle nodes (more stable than fastener type).
Force form
Steel supports mainly subjected to compression (such as vertical poles) need to focus on stability (aspect ratio control) to avoid instability;
The tensile strength and bending resistance shall be considered for the steel support (such as slant support and cantilever beam) under tension or bending, and high-strength steel (such as Q355) shall be selected.
3、 Follow material performance and specification standards
Steel material
The commonly used materials are Q235 and Q355 carbon structural steel:
Q235: Yield strength of 235MPa, suitable for scaffolding with small loads and low heights (such as floor standing scaffolding with a height ≤ 24m);
Q355: Yield strength of 355MPa, suitable for scenarios with high loads and heights (such as full scaffolding and tall formwork supports), with better strength and toughness.
It is prohibited to use steel with unknown materials and mechanical properties that do not meet the standards (such as non-standard recycled steel).
Specification parameters
The diameter and wall thickness of steel pipes: commonly used are φ 48.3 × 3.6mm (the main specification for fastener type scaffolding), φ 60 × 3.2mm (socket type), etc. The deviation of wall thickness should comply with the "Straight Seam Welded Steel Pipe" (GB/T13793) to avoid a decrease in bearing capacity due to insufficient wall thickness.
Length and connection method: Based on the design of the step distance of the upright and the spacing between the horizontal bars, fixed length steel pipes (such as 1m, 1.5m, 2m) are preferred to reduce cutting waste; The connection nodes need to be matched (such as fastener type with rotating fasteners, bowl fastener type with dedicated nodes).
