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[SEAOC] Re: [SEAOC] Rigid frame with masonry walls

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On the subject of crane lateral impact forces:  Be aware that the UBC
lateral seismic load for most cranes will be much higher than the crane
lateral impact.  The cranes, attached commonly near roof level, should
have a lateral seismic coefficient of 0.6.  Further, this seismic force
is applied concurrently with overall seismic frame loads, whereas the
crane impact forces need not be combined with seismic.  Spectacular
failures in the West San Fenando Valley in 1994 were a testament to the
lateral forces generated by building-mounted cranes.  The Crane
Manufacturers of America (CMAA) Specifications for the design of
overhead cranes specifically state that earthquake forces are not
considered.  Above all, do not rely on the "crane engineer" for lateral
seismic design forces.  He/she is playing with a different set of rules.

Russ Nester, SE, GE
rnester(--nospam--at)juno.com

____________________________________________________________
On Tue, 13 Aug 1996 13:27:37 PST "Martin Johnson" <mwj(--nospam--at)EQE.COM> writes:
>Well, I've seen it done before, and it seemed to work, if everything 
>was connected.  
>Generally the "end bays" of the frame as well as some longitudinal 
>bays
>have steel bracing to be compatible with the in-plane stiffness 
>of the masonry.  The interior moment frame bays can provide lateral 
>support to the masonry, often via one or more steel WF girts that are 
>turned sideways to attach to the wall .  Lateral deflection of the 
>frames 
>and wall should be checked for your wind loads, as well as for 
>lateral crane impact forces.  And I assume the masonry will have 
>rebar or joint reinforcing as well as frequent control joints.
>----------
>MWJohnson
>mwj(--nospam--at)eqe.com
>
>> Question: Is it practical to provide a high bay single story 
>building with 
>> steel rigid framing and masonry walls? 
>>  
>> I've seen buildings detailed this way, but I question whether the 
>masonry can 
>> handle the lateral movements to develop rigid frame action if it is 
>tied to 
>> the steel frame.  I am currently working on a building with a 3-ton 
>bridge 
>> crane, to be steel framed with masonry veneer (brick/CMU).  While a 
>rigid 
>> steel frame could handle the loads, I am inclined to go with a 
>braced frame to 
>> prevent damage to the masonry.  Has anyone encountered a rigid frame 
>building 
>> with masonry walls which has had damage due to the frame movement 
>due to 
>> lateral loads?  (This structure is in a low seismic area but 
>potential 
>> hurricane winds.) 
>>  
>> 
>> 
>> ...
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>> 
>Regards, MWJ
>
>Martin Johnson
>EQE International, Inc.
>mwj(--nospam--at)eqe.com
>
>...
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