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Re: Point load on garage diaphram

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By code, this load is "caused by a jack in for changing tires" (ASCE 7 C4.8.3).  Reasonably, that cannot take longer than seven days, hence Cd=1.25 (NDS Table 2.3.2). 
 
V. Steve Gordin, SE
Irvine CA
 
----- Original Message -----
Sent: Tuesday, August 04, 2009 19:34
Subject: RE: Point load on garage diaphram

What?s the justification for the 1.25 load duration factor in this case?

 

 

 


From: erik_g(--nospam--at)cox.net [mailto:erik_g(--nospam--at)cox.net]
Sent: Tuesday, August 04, 2009 5:28 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Point load on garage diaphram

 

Thanks to all that responded. Steve, I thought about applying the 1.25 increase for load duration, but I wasn't sure. I think I have it now.

-----Original Message-----
From: SGE Structural [mailto:sgordin(--nospam--at)sgeconsulting.com]
Sent: Tuesday, August 04, 2009 12:51 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Point load on garage diaphram

The heaviest non-commercial vehicle currently available is about 7,000 lbs loaded.  ASCE 7 (C4.8.3) assumes a 10,000-lb vehicle (possible for public garages, but unlikely for the private garages) with one wheel jacked up, 500 lbs for uneven distribution, hence 3,000 lbs.  Very conservative, but this is the minimum requirement of the code.

 

V. Steve Gordin, SE
Irvine CA

    

----- Original Message -----

Sent: Tuesday, August 04, 2009 12:27

Subject: Re: Point load on garage diaphram

 

The 3k load does seem a bit conservative. If the assumption is for the load per wheel, than the vehicle would weight about 12k. I'm not sure that is warranted. If the assumption is that the jack will be placed under the center or the axle, than the vehicle weight would be 6k. This seems more reasonable.

s.macie