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Re: Crane Runway Bracing Vibration

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This message was also sent by acnacionales(--nospam--at)gmail.com to: =?utf-8?Q?

Gary,

I would suggest using diagonal bracing at end bays instead of x-bracing at 
center bays and using a bigger section( l/r<120)  for the bracing.

Alex Nacionales

From: Gary L. Hodgson and Assoc.
Sent: ‎Friday‎, ‎June‎ ‎06‎, ‎2014 ‎4‎:‎46‎ ‎AM
To: seaint-seaosc(--nospam--at)mail-list.com

Fellow listers,
     I have a problem that I have never run into before. I designed a free
standing crane rwy for a 30 ton EOT crane.  The column centres are approx
28.5 ft, with only 5 bays and the columns are braced about the weak axis
by X-bracing in one bay (at centre of rwy, both sides) consisting of
L6x4x5/16 with the long leg horizontal, connected by a bolt where the 2
angles cross.
     When the crane starts up and starts travelling down-aisle, the
bracing vibrates to the annoyance of the customer and his workers. The
vibration is out of the plane of the X-bracing. This does not happen if
the crane starts elsewhere, and just passes over the braced bay.
     First, I had the existing bracing pulled tighter - did'n't work.
Next, I added reinforcing angles i.e, boxed the angles but that did not
solve the problem.  My next attempt will be to add a horiz strut between
the columns and then connect that to the X-bracing with a short length of
angle to the centre of the X-bracing so it will prevent or decrease the
amount of out-of -plane motion.
     Can any of the members suggest another solution?
Gary

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