Key points in steel structure design and calculation for 10T electric hoist truss gantry crane

I. Design Basis and Specifications

1. Main Specifications
   • “Crane Design Code” GB3811-83: Basis for core load calculation and allowable stress selection, using the semi-probabilistic analysis method.
   • “Steel Structure Design Code” GB50017-2003: For steel structure strength, stability, and joint design.
   • Other References: “Safety Regulations for Hoisting Machinery” GB6067-85, “General Gantry Cranes” GB/T14406-93, etc.
2. Design Parameters
   • Lifting Capacity: 10 tons (including spreader weight);
   • Span (Lk): Typical value: 20m (adjustable according to requirements);
   • Lifting Height (H): 10m;
   • Working Class: A3 (medium frequency of use).

II. Load Calculation

1. Static Load
   • Deadweight load: Includes the weight of the main beam, outriggers, electric hoist, etc., and must be calculated based on the material density and cross-sectional dimensions (e.g., Q345B low-alloy steel).
   • Lifting load: 10 tons rated load, considering a dynamic load factor of 1.1 (GB3811 requirements).
2. Dynamic load
   • Operating inertia force: Horizontal loads generated by acceleration and braking forces;
   • Wind load: Operating wind pressure is calculated as 250 Pa, and adjustments must be made to local wind pressure during non-operating conditions.
3. Load combination
   • Type II load combination: Used for main beam strength calculation (static load + dynamic load + wind load).

III. Main beam design calculation

1. Sectional characteristics
   • For truss main beams using box or H-section sections, calculate the moment of inertia (Ix, Iy) and bending modulus. For example, for a design, Ix = 2224147663.108 mm⁴.
   • Material selection: Q345B steel, yield strength 345 MPa, elastic modulus E = 210 GPa.
2. Strength and deflection verification
   • Strength: Calculate the bending normal stress based on the maximum bending moment (mid-span), which must meet the allowable stress (σ ≤ [σ]). Deflection: Mid-span deflection fmax = ML²/(8EI), allowable value ≤ L/400 (≤ 50mm for a 20m span).
3. Local Stability
   • Stiffener Arrangement: Prevent web buckling. Spacing is determined based on plate thickness and load.

IV. Outriggers and Connection Nodes

1. Outrigger Calculation
   • Compressive Stability: Verify slenderness ratio using Euler’s formula, maintaining λ ≤ 150.
   • Foundation Reaction: Calculate track beam bearing capacity based on wheel load distribution, with base coefficient k = 5.6 × 10⁴ kN/m³.
2. Joint Design
   • High-Strength Bolted Connections: Friction-type bolts are used between the main beam and the outriggers. Shear bearing capacity must meet load requirements.

V. Wind and Seismic Resistance Measures

1. Wind Resistance Design
   • Wind pressure in operating state is 250 Pa. In non-operating state, verify according to the local 50-year wind pressure.
   • Add windbreak cables or anchoring devices.
2. Seismic Requirements
   • Verify horizontal seismic effects according to the “Code for Seismic Design of Buildings,” focusing on checking the connection between the outriggers and foundation.

VI. Calculation Output

A complete calculation report should include:

1. Design parameters and code references;
2. Load calculation tables and combination results;
3. Strength, stiffness, and stability verification of the main beam and outriggers;
4. Joint details and bolt selection;
5. Wind resistance and foundation design specifications.