Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: bridge crane runway beams

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Typically one-half Iy is assumed to resist the lateral load (i.e., only the
top flange). If that does not work, it would be appropriate to weld a
channel cap on top of the wide flange to increase the lateral stiffness -
lateral strength/stiffness for such lateral loads is the primary purpose of
such channel caps you have seen in the past. A channel cap seems very
appropriate here given the long span you are dealing with. The crane trolley
can induce lateral forces on the runway due to lateral movement on the crane
bridge beam when under load, so some lateral stiffness is desirable to
maintain the track alignment. 

> -----Original Message-----
> From: Michael Hemstad [mailto:mlhemstad(--nospam--at)]
> Sent: Thursday, December 28, 2000 12:12 PM
> To: seaint(--nospam--at)
> Subject: bridge crane runway beams
> I'm designing a bridge crane runway.  The owner's
> specifications require adherence to CMAA 74, which in
> turn requires that lateral deflection be held to less
> than L/400 based on 10 percent of maximum wheel load
> without impact.  Does anyone know the intent of this? 
> What section properties are expected to be used?
> I assume that I should check the runway beam for
> bending based on this same lateral load in conjunction
> with the full vertical load.  Does anyone have a
> comment on this?
> In my particular case,  I have a 40 foot runway beam
> span (only a 2 ton crane). I find that a W21x83
> wideflange is adequate by itself, with vertical
> deflection of about L/1100 and lateral deflection of
> L/640. The lateral deflection is based on the 10
> percent of vertical moment acting laterally on the
> full beam Iy; i.e., I pretend that the lateral load is
> at the centroid of the beam instead of maybe 6 inches
> above the top flange.  Alternatively, I can weld a
> channel on top of a lighter wideflange, saving not
> very many pounds of steel but increasing lateral
> stiffness a good deal.  This is what I'm used to
> seeing, but I can't see a reason to do it here.  Am I
> missing something?
> Any help or comments would be appreciated.
> Mike Hemstad, P.E.
> TKDA Inc.
> St. Paul, Minnesota
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Photos - Share your holiday photos online!