Calculating the load-bearing capacity of steel grating is a specialized process involving materials mechanics, structural design, and specific application parameters. Below is a detailed breakdown of the calculation methods and key steps:
I. Key Parameters and Selection
1. Steel Grating Type
* Welded type: High load-bearing capacity, commonly used.
* Inserted type: Suitable for heavy-duty applications.
* Specifications need to be selected based on the height (e.g., 25mm, 30mm, 40mm), thickness (e.g., 3mm, 4mm, 5mm), and mesh spacing (e.g., 30×100mm, 40×100mm) of the load-bearing flat steel.
2. Load Type
* Uniformly distributed load: Commonly used for platforms, walkways, etc.
* Concentrated load: Vehicle wheel pressure, equipment support points, etc.
* Combined load: Requires calculation based on the most unfavorable conditions.
3. Span
* Load-bearing capacity is inversely proportional to the square of the span; span is the most sensitive factor affecting load-bearing capacity.
4. Boundary Conditions
* Simply supported: The most common calculation model.
* Fixed supported: Higher load-bearing capacity, rarely fully realized in practice.
II. Calculation Steps
1. Determine the Design Load
Static load (self-weight) + Live load (personnel, equipment, snow load, etc.) × Safety factor (usually 1.5~2.0).
2. Select Specifications and Obtain Parameters
Obtain the section modulus (W), moment of inertia (I), and weight per square meter from the supplier's manual.
3. Consider Long-Term Use Factors
In corrosive environments, allowances should be made for thickness.
In dynamic load applications, fatigue effects should be considered.
III. Simplified Methods and Tools
1. Manufacturer's Load Table
Most suppliers provide a "Load-Span Table," which can be directly consulted for model selection (safety factor already considered).
Example: G325/30/100 specification (flat steel 32×5mm, spacing 30mm), with a simply supported span of 1m, the uniformly distributed load is approximately 30 kN/m².
2. Design Software
Professional software such as GRASP and MBS can quickly calculate the load. 3. Standards Compliance
Chinese Standard: YB/T 4001.1-2019 "Steel Grating and Accessories"
International Standards: ISO 14122-2, EN 1431, ASTM A36, etc.
IV. Precautions
Local Concentrated Loads: The bending of individual flat steel bars needs to be checked; if necessary, shims should be added to distribute the load.
Installation Method: Welding or clamp fixing will affect boundary conditions.
Anti-slip Design: Serrated steel grating can improve anti-slip properties but will slightly reduce the theoretical load-bearing capacity.
Fatigue Loads: Frequent alternating loads require a reduction in allowable stress.
V. Recommendations
For critical projects, it is recommended to commission a structural engineer to perform professional calculations and refer to the technical data provided by the supplier.
For routine selection, the "Load-Span Table" can be used directly, with sufficient safety margin reserved.
