Overview
ISO 4302:2016 - Cranes - Wind load assessment specifies methods to assess wind loads acting on cranes. It covers both in-service and out-of-service wind conditions, provides a simplified calculation approach, and includes allowances for gusting and dynamic response. The standard is intended to be used in conjunction with ISO 8686-1 (load combinations) and ISO 20332 (proofs of competence for structural components).
Key topics and technical requirements
- Scope and assumptions
- Wind may blow horizontally from any direction, at a constant speed, and is treated as producing a static reaction on the crane structure.
- Built-in allowances address gusting (fluctuating wind speed) and dynamic response.
- Wind pressure
- Basic relation: p = 0.5 · ρ · v² (with ρ ≈ 1,225 kg/m³). In SI units this is commonly expressed as p = 0.625 · v² (p in N/m², v in m/s).
- In-service wind
- Design wind speeds and corresponding pressures are given (examples: 14 m/s → 125 N/m² for easily secured cranes; 20 m/s → 250 N/m² for normal open-site cranes; 28.5 m/s → 500 N/m² for process cranes).
- Wind loads on suspended (hoist) loads: F_H = c_H · A_H · p. If load geometry is unknown, assume c = 2.4 and A = 0.0005 · m_H² (m_H = hoist mass in kg).
- Structural member loading
- Member wind load: F = A · p · C_f where A is characteristic projected area and C_f is the shape coefficient (tables and guidance provided).
- Shape coefficients vary with aerodynamic slenderness, section ratio and flow regime (circular, box, lattice, clad structures).
- Shielding factors (η) are provided for arrays of frames/members to reduce loads on sheltered elements; effects accounted up to the ninth frame.
- Out-of-service (storm) wind
- Procedures for equivalent static out-of-service wind pressure, guidance on when and how to secure cranes, and reference storm wind speed maps (Annex A).
Practical applications and who uses ISO 4302:2016
- Crane designers and OEMs: to size members, select connections and specify securing devices.
- Structural and mechanical engineers: to calculate wind load combinations for design checks and fatigue assessments.
- Certifiers and conformity assessors: to validate proofs of competence referenced in ISO 20332.
- Plant operators and safety managers: to define operating limits, securing procedures and wind-related operating manuals.
- Regulators and inspectors: to reference industry-accepted wind load assessment methods.
Related standards
- ISO 8686-1:2012 - Cranes: design principles for loads and load combinations (load combinations B and C referenced).
- ISO 20332 - Proofs of competence for crane structural components (uses wind loads from ISO 4302).
Keywords: ISO 4302:2016, cranes wind load assessment, wind loads on cranes, in-service wind, out-of-service wind, wind pressure formula, shape coefficients, shielding factors, crane securing.
