huangyhg

all these crane collapses
one in new york. then another. this one in wyoming:
it seems we are seeing a rash of crane failures in the last several months. i wonder if this is a result of just a bunch of old cranes finally reaching the end of their lives vs. poor maintenance or what? i feel that bridges tend to at least have inspections performed every so often. does anyone know if there is an agency or inspection standard that these cranes must pass or is it totally up to the crane company/contractor to monitor?
public safety is definitely affected by this yet as a structural engineer i'm not sure whether there is an oversight by engineers in these things.

sounds like they were lifting a large section of tubular conveyor gallery into place. if they were lifting a 260 foot length of say, 10 foot diameter tube my guess would be that a slight breeze did them in. if it was a 500k lift it may have been that diameter of more. time will tell.
i don't know anything specific regarding any of the cases you mentioned, but the few folks i've met that do these sorts of big lifts are usually very careful types.
new york is experiencing a building boom.that means not enough inspectors,not enough experienced crane operators.it takes 40 of training to get a crane operators license ,there are lots of those but few with real experience.add to that the other typical construction situations .....the last one in nyc might involve a repaired part and the mayor said metallurgists have to take a close look. thanks mayor we metallurgists appreciate some mention !..it's sad that only a disaster gets people moving.
osha, ansi (asme) all require frequent, periodic and special inspections for all cranes in service or out of service for short or long period of time. the owners and the operators are all equally responsible for making sure that these inspections are performed on regular basis. also, these agencies and the crane manufacturer require that based on age and duty cycle work the crane's capacity must be reduced by as much as 15 to 50%. there are other considerations too that need to be considered while making a pick, like, wind velocity, direction of wind, out rigger support, or other anchorages, etc. i am not sure if the crane operators' even follow that. they all tend not to follow these requirements. also, being out of the crane's capacity chart can be devastating.

this one reminds me of the collapse of "big blue"...
i wonder what the safety factors (presuming asd design) are in the crane industry these days. as shin25 has pointed out, much of the operation is out of the hands of the designers as well...
sad; i very much hope everyone involved recovers quickly. further i hope that the incident is thoroughly investigated by independant auditors and finger pointing, if any, is done in a responsible, professional manner. no one means for this sort of thing to happen; god forbid it ever happens again. *knocks on wood*
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...
the collapse of big blue in milwaukee a few years ago was not due to operator error or crane equipment malfunction. it was due to a superintendant's decision, driven by schedule concerns, to make a lift during a wind higher than that allowed by operational proceedures. the mega cranes have very specific operational proceedures for a reason, but even the best plan can be undone by a dumb decision.
big blue really was big, it reportedly took 150 semi's to bring it into milwaukee.
in dealing with smaller cranes, you'll have a load chart, with the understanding that loads are reduced by wind loading, but no information is given by the manufacturers as to what that reduction actually is. i don't know if the situation is improved with larger cranes like this. even if an engineer is involved on the behalf of the crane operating company, there is a limit to what they can do without proper supporting information from the manufacturer.
wyoming is noted for wind- it just never stops up there.
seems like in the big blue case, that in fact, several of the operators were charged with errors.
the big issue in crane design is weight. the dead weight of the crane boom reduces the working load and reach. so if you can come up with a lighter boom, you have more lift capacity and more market for your crane. designing cranes conservatively won't help sales.

i wonder if the fact that experienced people are retiring in droves these days is a contributing factor. the operator of the recent collapsed crane in nyc was only 30.
i think by osha and ansi, the crane should not be operated if the wind is above 30 mph.

as a sailor, i know that 30 mph can be a lot of wind, and i also know that the wind velocity increases with altitude.

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