1 Scope
This standard gives recommendations and requirements for the stiffness properties of the structures for bridge and gantry cranes in terms of deflections and natural frequencies.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6974.1 Cranes — Vocabulary — Part 1: General (GB/T 6974.1-2008, ISO 4306-1:2007, IDT)
GB/T 6974.5 Cranes — Vocabulary — Part 5: Bridge and Gantry Cranes (GB/T 6974.5-2008, ISO 4306-1:2005, IDT)
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 6974.1 and GB/T 6974.5 apply.
4 Requirement
4.1 General
The effect of flexibility is demonstrated as elastic deformations under load and as vibrations induced by motion or force transients.
Excessive flexibility of structures and mechanical components of cranes can affect their safe use; therefore, elastic deformations and vibrations should be limited so that they do not cause dangerous situations, nor prevent the crane from being used in the intended manner. The requirements concerning the elastic deformations and vibrations depend upon the configuration of the crane and stem from the required accuracy of load handling, type and performance of the control system and location of the control station. However, the increased stiffness means increased investment costs and possibly larger space requirements, which may not be worthwhile in all applications. Furthermore, possibilities to eliminate flexibility depend very much on the type and configuration of the crane. Therefore, no exact limits are given for the deflections or the vibrations.
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Requirement
5 Recommendation for Pre-camber of Girders
6 Recommendations on Vibrational Frequencies of Crane Girders
Annex A (Informative) Guidance on Maximum Deflection (Stiffness Index) of Girders
Annex B (Informative) Guidance on Minimum Natural Frequencies of Bridge Crane girders
Annex C (Informative) Guidance on Minimum Vertical Natural Frequencies of Bridge and Gantry Cranes
