Crane Impact Loads

[igdelimb]

I am trying to find another reference to the crane impact loads. ASCE 7-05 Section 4.10 lists the following impact ratios for different type of cranes which is similar to AISC ASD 9th Edition Specifications for Structural Steel Buildings 1989.

ASCE 7-05 4.10.2 Vertical Impact Force. The maximum wheel loads of the crane shall be increased by the percentages shown in the following text to determine the induced vertical impact or vibration force:
a. Monorail cranes (powered) - 25%
b. Cab-operated or remotely operated bridge cranes (powered) - 25%
c. Pendant-operated bridge cranes (powered) - 10%
d. Bridge cranes or monorail cranes with hand-geared bridge, trolley, and hoist - 0%

Per commentary on the AISC ASD 9th Edition Specifications for Structural Steel Buildings 1989, these percentages are based on the Association of Iron and Steel Engineers publications (AISE 1979), so these percentages seems to be specific for bridge or overhead cranes supported by steel structures. I was wondering are there any other references for gantry cranes and their impact loads which are supported by concrete structures. Does anyone know ISO 12480 may have some guidance on the impact loads?

Thanks

 

[msquared48]

Why would the type of structure supporting it have any bearing on the required impact load to the crane components?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[ishvaaag]

Really not a material intrinsic issue but concrete PC or RC runways may show less dynamic effects upon some bigger stiffness present and so on. These things may be compounded to vary the impacrt factors.

 

[weab]

igdelimb,

Try CMAA Spec 74. This is the Crane Manufacturers Association of America. I think this is the best reference on the subject. The impact factor appears to be in the Hoist Load Factor (HLF). It states:

HLF = 0.15 < 0.005 x h oist speed in fpm < 0.5

where live load is factored by (1+ HLF). However, it includes several different factors so HLF cannot be used alone.

 

[BENDOG]

Also try AISC Design Guide #7 on Industrial Buildings.