Need a book? Engineering books recommendations...

# RE: Component Amplification factor a.p

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: Component Amplification factor a.p
• From: Rick.Drake(--nospam--at)Fluor.com
• Date: Thu, 11 Jul 2002 11:23:15 -0700
• Cc: seaint(--nospam--at)seaint.org

```No it is not just a straight ratio of periods.  It's a function of some
equations that include damping ratio and other Greek letters.

Rick Drake, SE
Fluor Daniel, Aliso Viejo, CA

*********

"Timothy P.
Spengler"            To:     <seaint(--nospam--at)seaint.org>
<timothyps@clea
npak.com>            cc:
07/11/02 10:57
AM                   Subject:     RE: Component Amplification factor a.p
to seaint                                                                                .....

Rick,

Thanks for the response.  Just a quick follow-up: Is a.p just a straight
ratio of the component period divided by the structure period, or do I need
to dig out my structural dynamic's book and do some research?

Tim

-----Original Message-----
From: Rick.Drake(--nospam--at)Fluor.com [mailto:Rick.Drake(--nospam--at)Fluor.com]
Sent: Thursday, July 11, 2002 10:44 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Component Amplification factor a.p

The a-sub-p factor in the 1997 UBC represents the dynamic amplification
factor, relating the dynamic properties of the component to that of the
structure. Knowing the fundamental period of both the component and the
structure, this value can be exactly determined using basic dynamic
principles.

However,  since  this  value  is not practical, a-sub-p has been assigned a
value  based  on  whether  the  component  is either "rigid" or "Flexible",
a-sub-p  of  1.0  and  2,5 respectively.  This is analogous to the 1994 UBC
method of multiplying C-sub-p times 2 for flexible items.

If  your  equipment  is rigid, and not on vibration isolators (see footnote
14), a-sub-p of 1.0 is appropriate.  If not, a-sub-p of 2.5 is appropriate.

Rick Drake, SE
Fluor Daniel, Aliso Viejo, CA

Regards,

Rick Drake, SE
Fluor Daniel, Aliso Viejo, CA

*********

"Timothy P.
Spengler"            To:     <seaint(--nospam--at)seaint.org>
<timothyps@clea
npak.com>            cc:
07/11/02 10:30
AM                   Subject:     Component
Amplification factor a.p
to seaint
.....

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.

-----------------------------------------------------------------------------------------------------

The information transmitted is intended only for the person
or entity to which it is addressed and may contain confidential
and/or privileged material. If you are not the intended recipient
of this message you are hereby notified that any use, review,
retransmission, dissemination, distribution, reproduction or any
action taken in reliance upon this message is prohibited. If you
material from any computer.  Any views expressed in this message
are those of the individual sender and may not necessarily reflect
the views of the company.
-------------------------------------------------------------------------------------------------------

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********

-----------------------------------------------------------------------------------------------------
The information transmitted is intended only for the person
or entity to which it is addressed and may contain confidential
and/or privileged material. If you are not the intended recipient
of this message you are hereby notified that any use, review,
retransmission, dissemination, distribution, reproduction or any
action taken in reliance upon this message is prohibited. If you
material from any computer.  Any views expressed in this message
are those of the individual sender and may not necessarily reflect
the views of the company.
-------------------------------------------------------------------------------------------------------

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted