Need a book? Engineering books recommendations...

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

Re: Parking Garage Loading - IBC/UBC

[Subject Prev][Subject Next][Thread Prev][Thread Next]
This is my opinion on parking garage loading (taken from something I wrote):

********************
While most building codes and standards specify a live load of 50 psf for parking structures, permissible live load reductions vary widely. The IBC, the BOCA National Building Code, and the ASCE 7 Standard do not allow live load reduction for horizontal members but allow a 20% live load reduction for columns supporting two or more floors.  The Uniform Building Code (UBC) allows a maximum 40% reduction for both horizontal members and columns.  The Standard Building Code (SBC) allows a maximum of 40% reduction for horizontal members and 60% for columns.

The use of live load reduction in parking garages is typically justified because actual automobile weight in a fully loaded parking garage will seldom exceed 25 to 30 psf.  A nominal added reserve capacity may be desirable to account for future dead loads such as overlays, however.

*******************************

The critical stage for collapse is probably during construction.  The precast parking garage that collapsed in Maryland last fall was an 8-story garage.  I heard (from someone "close to the investigation") that there may have been a problem with how many levels they had erected without having welded the flanges.  Eight stories is actually somewhat tall for a parking garage - owners have figured out that the top stories never get used, because people don't want to drive up a mile of ramps to find a parking space.  In the garage in Maryland,   the erectors may only previously have done three or four story garages,  and thus not had a problem with leaving flanges up welded.

Gail Kelley