Crane impact factor
Crane impact factor
(OP)
When designing runway beams, brackets, etc. what would be the more appropriate vertical impact factor to use for a radio-controlled crane, 10% (pendant-operated crane) or 25% (cab-operated crane)?
I cannot find this info in AISC, ASCE, etc. but my thoughts are that since a person does not need to walk with the crane, the 25% impact factor would be more appropriate.
Thanks for the input.
I cannot find this info in AISC, ASCE, etc. but my thoughts are that since a person does not need to walk with the crane, the 25% impact factor would be more appropriate.
Thanks for the input.






RE: Crane impact factor
RE: Crane impact factor
RE: Crane impact factor
"Cab operated or remotely operated" = 25%
Radio = Remotely
RE: Crane impact factor
RE: Crane impact factor
A couple other notes though:
1. Approximately 40% of the hoists sold these days use VFD motor controls which provides very soft starts & stops of hosit motion - hence reducing verical impact. We will allow a beam closer the edge when we know VFD hoists are being used.
2. We tradionally try to keep our delfections down to about 80% of allowable. Mostly due to customer perception concerns. Very often, a next size deeper beam will have the same weight (cost) and still be OK in the other charecteristics.
3. For the Crane's girder design, CMAA directs that we increase the impact factor when hoist speed increases:
15% minimum
.5% per fpm of rated hoist speed, but not exceed 50% unless magnet of bucket duty.
Interesting how this is so different from Tech 13
Note that impact is not used when running deflection checks.
RE: Crane impact factor