Overview
ISO 22986:2007 - "Cranes - Stiffness - Bridge and gantry cranes" gives guidance and requirements for the stiffness properties of bridge and gantry crane structures in terms of static deflections and natural frequencies. The standard helps ensure safe, accurate load handling and acceptable vibration behaviour without prescribing specific strength details. It is intended as a design and verification reference for stiffness-related aspects of crane structures.
Key topics and requirements
- Scope: Recommendations and requirements for elastic deformations and vibration properties of bridge and gantry cranes.
- Basic requirements for elastic deformation - elastic deformations shall not:
- cause collisions with surrounding objects;
- prevent trolley/crab movement and braking under dynamic test load;
- prevent safe holding of position under static test load;
- induce excessive transverse forces on rails or prevent crane travel;
- cause misalignment that leads to premature wear, vibration or brake failure.
- Pre-camber guidance: Pre-cambering girders is permitted to reduce operational deflection and improve trolley positioning; it does not affect girder strength.
- Vibrational criteria:
- Operator cabin vertical natural frequency should generally be ≥ 2 Hz (lower allowed for long spans, with measures to reduce amplitude/duration).
- For gantry cranes in process duty, horizontal frequency from main motion should be ≥ 0.50 Hz.
- Annex B provides approximation formulas for vertical and horizontal natural frequencies (use SI units) and recommended constants for support conditions (freely supported, clamped, typical top-running cranes).
- Girder proportions (welded box girders):