Overview
ISO 8686-2:2018 - Cranes: Design principles for loads and load combinations - Part 2: Mobile cranes applies the general principles of ISO 8686‑1 to mobile cranes (as defined in ISO 4306‑2). It specifies the loads and load combinations to be used in proof‑of‑competence calculations for the steel load‑supporting structures of mobile cranes used in normal and duty‑cycle service. The standard focuses on the design assumptions (accelerations, side loading, erection/dismantling states, automatic cut‑outs) required to evaluate structural strength and stability; test procedures for proof‑of‑competence are addressed in separate documents.
Key technical topics and requirements
- Scope: Applies to mobile cranes for normal and duty cycle service; excludes detailed test methods (handled elsewhere).
- Load selection & combinations: Tables in the standard (Table 1, Table 2) define combinations for both the allowable stress and limit state design approaches, including overall strength coefficients (γ) and partial load factors.
- Acceleration effects: Rules for slewing, hoisting, driving, luffing and telescoping accelerations; loads on the crane mass are amplified by a dynamic amplification factor (φ) per ISO 8686‑1.
- Simultaneous accelerations: Guidance (Annex A) limits assumed simultaneous accelerating drives (hoisting plus one drive; otherwise up to two drives).
- Side loading: Addresses sources of side loads (slewing, wind, reeving offsets, boom foot inclination). Minimum lateral forces for slewing must not be taken less than the greater of:
- 1% of rated load + 1% of boom/jib mass (reduced to boom/jib head), or
- 2% of rated load for latticed booms (3% for telescopic booms).
- Erection & dismantling: Requires separate evaluations for each significant step using the load combination rules (load combination group B).
- Automatically initiated actions: Includes calculations for emergency cut‑outs/automatic braking (column C4).
- Special limits: Latticed booms and fly jibs supported by wire rope must have side‑load deflection ≤ 2% of effective length under rated load plus 2% side load; verify by calculation and test (see ISO 11662‑2).
Practical applications and users
ISO 8686‑2 is essential for:
- Crane designers and structural engineers developing or validating mobile‑crane steel structures
- Manufacturer design verification and proof‑of‑competence calculations
- Test laboratories and certification bodies evaluating structural competence
- Asset owners, safety engineers and maintenance teams concerned with structural integrity, erection/dismantling safety and compliance
Keywords: ISO 8686-2, mobile cranes, loads and load combinations, proof-of-competence, crane design, side loading, dynamic amplification factor, allowable stress, limit state.
Related standards
- ISO 8686‑1:2012 - General design principles for loads and load combinations
- ISO 4306‑2 - Vocabulary: Mobile cranes
- ISO 4305 - Mobile cranes: Determination of stability
- ISO 11662‑2 - Experimental determination: structural competence under static loading
- ISO 20332 - Proof of competence of steel structures
- ISO 10721‑1 / ‑2 - Steel structures: materials, design, fabrication and erection
- ISO 4310 / ISO 4302 - Test code / Wind load assessment
For implementation, consult the full ISO 8686‑2:2018 document and referenced standards to ensure correct interpretation of tables, factors and annex guidance.
Open preview (PDF)Cranes — Design principles for loads and load combinations — Part 2: Mobile cranes
