Need a book? Engineering books recommendations...

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

Component Amplification factor a.p

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I'm designing what could best be classified as a "structural" suspended ceiling grid.  It's similar to a standard suspended ceiling, except much stronger.  The system will be hung from a roof superstructure using 3/4" diameter threaded rods and laterally braced with pre-stretched wire rope.  The ceiling grid itself consists of 4" deep x 2" wide aluminum extrustion tubes laid out on a 2' x 4' grid pattern and will support, on average, 10 psf of self weight plus 12 psf of additional load suspended for the ceiling.  The ends of the aluminum extrusions will be fully welded.
 
On the advise of another engineer, my client is dictating that a component amplification factor of 2.5 be used for the seismic design of this system.  Upon researching this item in the UBC and the California blue book I was able to technically determine that my system had a fundamental period greater than 0.06 and could therefore be classified as a flexible component and require an amplification factor of 2.5.  However, there are numerous items in Table 16-0 of the UBC that closely match my system (such as suspended ceilings, conduits and piping.) yet only require an amplification factor of 1.0.  In addition, the blue book seems to indicate that the potential for seismic amplification is reduced if a system is ductile, therefore resulting in a amplication factor of 1.0.  However, this is only mentioned once and I would not consider it amble evidence to refute using an amplification factor of 2.5.
 
My question to the group is 1) Is there a more technically refined way that I could prove that my system can be designed using an amplification factor of 1.0? and 2) Does anybody know of any additional sources that have a more detailed discussion of parts and portions seismic analysis?
 
Thanks
 
 
Tim Spengler SE
Portland, Oregon.