ISO 08686-1 pdf download – Cranes – Design principles for loads and load combinations— Part 1: General.
63.4 Tilting forces
If a crane with horizontally restrained load can tilt when It, Its load or Its lifting attachment collides with an obstacle, the resulting static forces shall be determined.
If a tilted crane can fall back into Its normal position in an uncontrolled manner, the resulting impact on the supporting structure shall be taken into account.
63.5 UnintentIonal loss of payload
The effects of unintentional loss of the payload shall be taken into account, especially subsequent rigid body stability issues and strength issues such as the jib or whole crane structure springing back, the jib whipping backwards and colliding with the crane structure, the jib falling back into normal position or the reversal of loads in components designed as unidirectional (hydraulic cylinders, tension ties, etc.).
In cases where dynamic analysis Is not performed, the effect of unintentional loss of the payload may be calculated by applying the dynamic factor, -0,3.
63.6 Loads caused by emergency cut-out
Loads caused by emergency cut-out shall be evaluated in accordance with 6.1.4, taking into account the most unfavourable state oldrive (I.e. the most unfavourable combination of acceleration and loading) at the time of the cut’out. The value of the factor hall be chosen from the range 1.5 s 2.
63.7 Loads caused by failure of mechanism or components
Where protection Is provided by emergency brakes In addition to service brakes, failure and emergency brake activation shall be assumed to occur under the most unfavourable condition. Where mechanisms are duplicated for safety reasons, failure shall be assumed to occur in any part of either system.
In both these cases, the resulting loads shall be evaluated in accordance with 6.1.4, taking into account any impacts resulting from the transfer of forces.
6.4.1 Loads due to erection, dismantling and transport
The loads actingat each stage oftheerection and dismantling process shall be taken into account, including those arising from a wind speed oIH,3 mis or greater. Higher values may be specified for the specific types of cranes covered by the other parts of ISO 8686. They shall be combined in accordance with 7.2.
In some cases It may also be necessary to take account of loads occurring during transport.
6.4.2 Loads on platforms and other means provided for access
The loads are considered to be local, acting only on the facilities themselves and on their immediate supporting members.
The following loads shall be taken into account:
— 3 000 N. where materials can be deposited;
— 1 500 N, on means provided for access only:
— not less than 300 N. horizontally on railings, depending on location and use.
7 PrincIples of choice of load combinations
7.1 Basic considerations
Loads shall be combined to determine the stresses a crane will experience during normal operation as simulated by an elastostatic calculation. To achieve this,
a) the crane is taken in Its must unfavoiirable attitude and configuration while the loads are assumed to act in magnitude, position and direction causing unfavourable stresses at the critical points selected for evaluation at the basis of engineering considerations, and
b) conservatively, loads can be combined at the values defined in this part of ISO 8686 or, when appropriate, they can be combined with some loads factored to more closely reflect loading conditions actually found In practice.
Basic load combinations are given in Table 3. In general, load combinations A cover regular loads, load combinations B cover regular loads combined with occasional loads and load combinations C cover regular loads combined with occasional and exceptional loads.
ISO 08686-1 pdf download – Cranes – Design principles for loads and load combinations— Part 1: General
