GB/T 22437.5-2010 is Part 5 of the crane load and load combination series, establishing load classification and combination rules specific to the load characteristics and operating conditions of overhead and gantry cranes. As the most widely used crane types worldwide, their load combination calculations serve as a representative reference for the industry. This article provides a systematic interpretation of the standard's core content.

Standard Scope and Load Characteristics of Overhead & Gantry Cranes

GB/T 22437.5-2010 is dedicated to load calculations for overhead and gantry cranes. The structural configuration of these cranes dictates their unique load analysis requirements: the box-type structure formed by the main girder and end carriages primarily resists vertical bending loads; trolley travel along the crane rail generates localized wheel load concentrations; and horizontal inertia forces during crane travel, along with skewing lateral forces, impose additional horizontal loads on the end carriages and crane rail. Unlike mobile or tower cranes, wind load has a relatively minor effect on overhead and gantry cranes — wind load is not considered for indoor installations, and only outdoor gantry cranes require wind load calculations. Additionally, the trolley wheel load is a critical source of local stress in the main girder and must be evaluated separately.

Load Classification

Primary loads (P) — dead weight (mass of all structural components and attachments, including main girder, end carriages, trolley frame, operator cab, electrical equipment, and walkways), lifting load (rated lifting capacity plus the weight of the lifting spreader and the suspended portion of the wire rope), and inertia forces from dead weight (horizontal inertia forces generated during trolley and crane travel start/braking). The hoisting dynamic factor φ₂ ranges from 1.0 to 1.6 depending on lifting speed and drive mode. The travel impact allowance φ₃ (impact load on the trolley and crane bridge when traversing rail joints) ranges from 1.0 to 1.4.

Additional loads (A) — wind load (applicable only to outdoor gantry cranes; working-condition wind pressure of 250 N/m², storm conditions based on a 50-year return period), temperature load (thermal expansion stress must be considered when the crane length exceeds 80 m or when the fabrication-to-installation temperature differential exceeds 20°C), and snow load (in regions where snow accumulation is possible).

Special loads (S) — erection and dismantling loads, buffer collision loads, and test loads (static test at 1.25 times rated load and dynamic test at 1.1 times rated load). For overhead and gantry cranes, buffer collision energy is calculated at 85%–100% of the rated crane travel speed, multiplied by a dynamic load factor of 1.0–1.5.

Load Combination Cases

The standard defines three fundamental load combinations for overhead and gantry cranes:

Case A (normal operation, no wind) — P, used for strength verification of the main girder and end carriages of overhead cranes under indoor, wind-free conditions. Safety factor n≥1.22 (relative to yield strength n=1.48; relative to tensile strength n=2.5). Under this case, the vertical static stiffness and dynamic stiffness of the main girder must also be verified — mid-span deflection under full load must not exceed L/750, and the natural frequency of the main girder with the trolley positioned at mid-span must be ≥2 Hz.

Case B (operation with wind, outdoor) — P+A, used for strength verification of outdoor gantry cranes under working conditions, with working wind load superimposed. Safety factor n≥1.22.

Case C (storm, non-working) — P+storm A, used for strength verification of outdoor gantry cranes in the non-working condition (after the crane has traveled to its anchoring position and the rail clamps are engaged). Safety factor n≥1.10.

For overhead and gantry cranes, the governing load combination is Case A — with the trolley fully loaded at mid-span, the main girder experiences maximum bending stress and deflection; with the trolley fully loaded at the girder end, the main girder experiences maximum shear stress. Strength, stiffness, and stability of the main girder must be verified at both critical trolley positions.

Trolley Wheel Load Calculation

The standard places particular emphasis on the calculation of trolley wheel loads: P_w = (Q + G_t + G_h)/n, where Q is the rated lifting capacity, G_t is the trolley dead weight, G_h is the hook block weight, and n is the number of wheels. Wheel load distribution must account for the trolley position along the crane rail — when the trolley is positioned near one end, the load distribution across the four wheels becomes uneven, with increased load on the wheels closest to that end. The localized compressive stress induced in the main girder web plate by wheel loads must be verified independently (web height-to-thickness ratio and web thickness must satisfy local stability requirements). The standard recommends installing longitudinal stiffeners on the main girder web plate at the rail positions to enhance resistance to localized compressive forces.

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Frequently Asked Questions

Q: What international standards do your cranes comply with?
A: Our cranes are designed in accordance with ISO 4301 for classification and IEC 60204-32 for electrical safety, among other relevant international standards.

Q: Can you customize a crane for a specific industrial process?
A: Absolutely. We offer fully customized solutions, including variations in span, lifting height, and control systems, to meet the precise demands of your application.

Q: What kind of after-sales support do you provide?
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Special Loads on Gantry Cranes

A: Compared to overhead cranes, gantry cranes are subject to additional load conditions that must be accounted for in structural design. These include wind load on the outriggers—which, given their height (up to 30 m or more), generates significant horizontal forces and bending moments at the outrigger-to-portal-frame connections. The overturning moment on the outriggers when the trolley is fully loaded at the cantilever end is another critical factor. Additionally, skewing of the crane bridge during travel—caused by synchronization deviations between the two ends—produces horizontal lateral forces perpendicular to the crane rail, acting on the wheel flanges and rail sides. The standard specifies that the skewing lateral force F_s shall be calculated as (1/8~1/10) of P_w, where P_w is the maximum wheel load of the crane bridge wheel. For outdoor gantry cranes, the wind load on rail clamps and anchor devices under storm conditions must also be evaluated. Kelude Heavy Industry strictly follows ISO 4301 load spectrum classification in the structural design of overhead and gantry cranes, ensuring structural strength meets all operating condition requirements.

Load Combination Comparison: Overhead vs. Gantry Cranes

The comparison table below outlines the core parameter configurations for load combinations in overhead and gantry cranes, serving as a reference for selection and operational planning.

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