GB/T 22437 consists of five parts, under the general title Cranes — Design Principles for Loads and Load Combinations:
— Part 1: General;
— Part 2: Mobile Cranes;
— Part 3: Tower Cranes;
— Part 4: Jib Cranes;
— Part 5: Overhead Travelling and Portal Bridge Cranes.
This part is Part 1 of GB/T 22437.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 22437.1-2008 Cranes — Design Principles for Loads and Load Combinations — Part 1: General in whole, and the following technical deviations have been made with respect to the GB/T 22437.1-2008:
— "partial load coefficient" is modified as "partial safety factor" (see Clause 4, Table 1; Clause 4 of Edition 2008, Table 1);
— "φ9: factor for dynamic effects from unintentional loss of payload" is added (see Clause 4, Table 1);
— The provision that "when applying this part to the different types of cranes, operating in the same service and environmental conditions, equivalent resistance to failure should be sought." is moved from Clause 1 to Clause 5 (see 5.1; Clause 1 of Edition 2008);
— The provision that “the limit state method is a prerequisite if this part is applied together with ISO 20332 and/or the 2nd order method” is added in the limit state method (see 5.2);
— The categories of loads are moved from Clause 6 to Clause 5 (see Clause 5; Clause 6 of Edition 2008);
— "when lifting the gross load off the ground" is modified as "when lifting the pay load off the ground" (see 6.1.1; 6.1.1 of Edition 2008);
— The calculation formula of φ2 and corresponding values in Table 2 are modified (see 6.1.2.1.1; 6.1.2.1 and 6.1.2.2 of Edition 2008);
— The expression of "accuracies of wheel axle parallelism" is added (see 6.2.2);
— The expression of "in the proof calculation for test load situations, a minimum level of wind of 5.42 m/s shall be taken into account" is added (see 6.3.2);
— "Unintentional loss of payload" is added (see 6.3.5);
— "Masses of crane and crane parts" is added (see 7.3.7);
— "Favourable and unfavourable masses" is added (see 7.3.7.1);
— “Partial safety factors for the masses of the crane" is added (see 7.3.7.2);
— “Safety factors for the masses of the crane" is added (see 7.3.7.3);
— “Partial safety factors to be applied to loads caused by displacements" is added (see 7.3.8);
— “Partial safety factors for the proof of rigid body stability" corresponding values in Table 7 are added (see 7.4);
This part is identical with International Standard ISO 8686-1:2012 Cranes — Design Principles for Loads and Load Combinations — Part 1: General by means of translation.
The Chinese documents identical to the normative international documents given in this part are as follows:
— GB/T 5905-2001 Cranes — Test Code and Procedures (ISO 4310:2009, IDT).
— GB/T 6974 (all parts) Lifting Appliances — Vocabulary [ISO 4306 (all parts)]
— GB/T 30024-2013 Cranes — Proof of Competence of Steel Structures (ISO 20332:2008, IDT)
For the purposes of this part, the following editorial changes have also been made
— The formulas in the text and annexes are numbered uniformly;
— In C.2.4 of Annex C, the formula for the relation between coefficient ξ and coefficient α is modified to take absolute value.
This part was proposed by China Machinery Industry Federation.
This part is under the jurisdiction of the National Technical Committee 227 on Hoisting Machinery of Standardization Administration of China (SAC/TC 227).
The previous editions of this part are as follows:
— GB/T 22437.1-2008.
Cranes — Design Principles for Loads and Load Combinations — Part 1: General
1 Scope
This part of GB/T 22437 specifies general methods for the calculating loads and principles to be used in the selection of load combinations for proofs of competence for the structural and mechanical components of cranes as defined in ISO 4306-1.
This method is based on rigid body kinetic analysis and elastostatic analysis but expressly permits the use of more advanced methods (calculations or tests) to evaluate the effects of loads and load combinations, and the values of dynamic load factors, where it can be demonstrated that these provide at least equivalent levels of competence.
This part provides for two distinct kinds of application:
a) the general form, content and ranges of parameter values for more specific standards to be developed for specific types of cranes;
b) a framework for agreement on loads and load combinations between a designer or manufacturer and a crane purchaser for those types of cranes where specific standards do not exist.
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.
ISO 4302 Cranes — Wind Load Assessment
ISO 4306 (all parts) Lifting Appliances — Vocabulary
ISO 4310 Cranes — Test Code and Procedures
ISO 20332 Cranes — Proof of Competence of Steel Structures
3 Terms and Definitions
For the purposes of this document, the definitions given in ISO 4306 and the following apply.
3.1
load or loads
external or internal actions in the form of forces, displacements or temperature, which cause stresses in the structural or mechanical components of the crane
3.2
analysis
study of the movement and the inner forces of systems modelled by elements that are assumed to be non-elastic
3.3
analysis
study of the relative elastic displacements (distortion), movement and the inner forces of systems modelled by elements that are assumed to be elastic
4 Symbols
The main symbols used in this part are given in Table 1.
Table 1 Main symbols
Symbol Description Reference
φi Factors for dynamic effects Various
φ1 Factors for hoisting and gravity effects acting on the mass of the crane 6.1.1, Table 3
φ2 Factor for hoisting a grounded load 6.1.2.1, Table 3
φ3 Factor for dynamic effects of sudden release of part of load 6.1.2.2, Table 3
φ4 Factor for dynamic effects of travelling on an uneven surface 6.1.3.2, Table 3
φ5 Factor for dynamic loads arising from acceleration of crane drives 6.1.4, 6.3.6, Table 3
φ6 Factor for effects of dynamic load tests 6.3.2, Table 3
φ7 Factor for elastic effects arising from collision with buffers 6.3.3
φ9 Factor for dynamic effects from unintentional loss of payload 6.3.5, Table 3
α Hoisting classes assigned to cranes 6.1.1
HC1 to HC4 Factor assigned to hoisting class 6.1.2.1.2 to 6.1.2.1.4
β2 Term used in determining the value of φ3 6.1.2.1.1 to 6.1.2.1.2, 6.1.2.1.5
β3 Steady hoisting speed, in metres per second 6.1.2.2
vh Buffer forces 6.1.2.1.3 (Table 2b)
Fx, Fx2, Fx4 Coefficients for calculating allowable stresses 6.3.3
γf Partial safety factor 7.3.2
γp Resistance coefficient 7.3.3, Table 3, 7.3.7.2, 7.3.8, A.3
γm Coefficient for high-risk applications Table 3, Annex A
γn Mass of pay load 7.3.6, Annex A
m Mass of the gross load 6.1.2.2
mH Mass of that part of the hoist load remaining suspended from the crane 6.1.2.1.1,6.3.1
ηm=mH-ΔmH Factors for dynamic effects 6.3.1
Note: Further symbols are used in the annexes and are defined therein.
5 General
5.1 General principles
The objective of proof of competence calculations carried out in accordance with this part is to determine mathematically that a crane will be competent to perform in practice when operated in compliance with the manufacturer’s instructions.
The basis for such proof against failure (e.g. by yielding, elastic instability or fatigue) is the comparison between calculated stresses induced by loads and the corresponding calculated strengths of the constituent structural and mechanical components of the crane.
Proof against failure may also be required in respect of overturning stability. Here, the comparison is made between the calculated overturning moments induced by loads and the calculated resistance to overturning provided by the crane. In addition, there may be limitations on forces that are necessary to ensure the stability and/or to avoid unwanted displacement of portions of the crane or of the crane itself, for example, the jib support ropes becoming unloaded or the crane sliding.
The effects of differences between actual and ideal geometry of mechanical and structural systems (e.g. the effect of tolerances, settlements, etc.) shall be taken into account. However, they shall be included specifically in proof of competence calculations only where, in conjunction with applied loads, they may cause stresses that exceed specified limits.
When applying this part to the different types of cranes, operating in the same service and environmental conditions, equivalent resistance to failure should be sought.
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Symbols
5 General
5.1 General principles
5.2 Methods of proof of competence calculations
5.3 Assessment of loads
5.4 Categories of loads
6 Loads and Applicable Factors
6.1 Regular loads
6.2 Occasional loads
6.3 Exceptional loads
6.4 Miscellaneous loads
7 Principles of Choice of Load Combinations
7.1 Basic considerations
7.2 Load combinations during erection, dismantling and transport
7.3 Application of Table
7.4 Partial safety factors for the proof of rigid body stability
Annex A (Normative) Application of Allowable Stress Method and Limit State Method of Design
Annex B (Informative) General Guidance on Application of Dynamic Factors φi
Annex C (Informative) Example of Model for Estimating Value of Dynamic Factor φ4 for Cranes Travelling on Rails
Annex D (Informative) Example of Determination of Loads Caused by Acceleration
Annex E (Informative) Example of Method for Analysing Loads due to Skewing
Annex F (Informative) Illustration of Types of Hoist Drives
Bibliography
