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RE: Seismic Load Value R for Pile Foundation

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Hi Larry,

R value is based on the building frame system and seismic force resisting 
system.  It sounds like you are utilizing the piles as a cantilever 
concrete column system, where the pile extends above the hillside grade to 
support the residence.  The devil is in the details so to speak.  It 
depends on moment frame design and detailing requirements for the 
column/pile (only) you elect to use.   Per ASCE Table 12.2-1 (bear with me, 
 but I am still in ASCE 7-05 mode), the R values for the various concrete 
moment frame requirements are:

2.5 (Special Reinforced MF)
1.5 (IMP)
1.0 (Ordinary MF)

It looks like these values have not changed in ASCE 7-10.

Pretty low R values.


Ricardo G. Gonzalez, P.E.
C S W | S T 2
CSW/Stuber-Stroeh Engineering Group, Inc.
45 Leveroni Court, Novato, CA  94949
Civil Engineering ∙ Structural Engineering
Planning ∙ Land Surveying & Mapping

main: 415-883-9850          fax: 415-883-9836
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-----Original Message-----
From: seaint-seaosc(--nospam--at) [mailto:seaint-seaosc(--nospam--at)] On 
Behalf Of refugio Sent: Monday, January 13, 2014 12:08 PM
To: seaint-seaosc(--nospam--at)
Subject: Re: [SEAINT-SEAOSC] Seismic Load Value R for Pile Foundation

from asceWhere construction employing posts or poles as columns embedded in 
 earth or embedded in concrete footings in the earth is used to resist 
lateral loads, the depth of embedment required for posts or poles to resist 
 seismic forces shall be determined by means of the design criteria 
established in the foundation investigation report.

---- On Mon, 13 Jan 2014 06:38:25 -0800 <lrhauer(--nospam--at)> wrote ----

What R value should be used for seismic analysis of concrete friction piles 
 that support a light framed residence on hillside condition? The pile 
depth is determined by the flag-pole formula

Thanks in advance,

Larry Hauer, S.E.

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