1. Material strength and anti-corrosion treatment
Carbon steel characteristics: Carbon steel has high strength (yield strength is usually above 235MPa), but it is prone to rust and needs to be treated with galvanizing, powder coating or anti-rust paint to extend its service life.
Section selection: Commonly used profiles include I-beams, channel steels, square tubes, etc. The section dimensions (such as height and wall thickness) directly affect the load-bearing capacity. For instance, the load-bearing capacity of square tubes of 40×40×3mm and 20×20×2mm varies significantly.
2. Rationality of structural design
Layout and support: The spacing of the keel (usually ≤1.2 meters) and the support position of the platform beam should conform to the mechanical distribution to avoid local stress concentration.
Deflection control: According to the specification, the deflection should be ≤ 1/250 of the span (for example, if the span is 3 meters, the deflection should be ≤12mm), and it needs to be verified through the calculation of the moment of inertia of the section.
3. Connection type
Welding: High strength, but it is necessary to prevent deformation and weld quality defects (such as pores and slag inclusions).
Bolt connection: Easy to disassemble, but embedded parts or high-strength bolts (such as grade 8.8) are required to ensure shear resistance.
Riveting: Less used, mostly in special scenarios.
4. Load type and safety factor
Static load: Self-weight (carbon steel density approximately 7.85g/cm³) + step material (such as concrete, wood).
Dynamic load: The live load is taken in accordance with the national standard (such as GB 50017-2017), usually ≥3.5kN/m², and the dynamic coefficient (1.5 to 2 times) is considered.
Safety reserve: A safety factor of at least 1.5 times should be reserved during the design process.
5. Construction and installation quality
Verticality and levelness: Excessive deviations can lead to uneven force distribution and require calibration with a level.
Foundation fixation: Embedded parts or expansion bolts should be inserted into the concrete base by ≥50mm to prevent loosening.
6. Environmental factor
Corrosion protection: In coastal or humid areas, the thickness of the galvanized coating should be increased (≥85μm) or stainless steel should be used.
Temperature influence: In areas with large temperature differences, thermal expansion and contraction should be taken into account, and expansion joints should be reserved (1 to 2mm per meter of length).