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RE: Palo Alto grade beam and piers

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The 1.33 factor is for ASD only.  Concrete for piers should be done in
strength design.  

There is a procedure in an earthquake engineering book by Dowrick which
speaks to this issue.  He suggests that the confining steel be designed for
the lateral strength of the pier.  The idea is to have the mode of failure
in bending as opposed to shear.

Harold Sprague, P.E.
The Neenan Company

-----Original Message-----
From: Sandra Estrella [mailto:sestrella(--nospam--at)]
Sent: Friday, October 23, 1998 5:32 AM
To: seaint(--nospam--at)

Hi everyone,
I have a project in Palo Alto where I have a pile(pier) and Grade beam
The pile(pier)  is 16" Dim. and 12'-00" deep  with 4-# 5 vertical
reinforcement and originally  I had spaced my transverse reinformence
with # 3 bars @ 16" o.c.  The plan chker. wants me to use section
1809.5.2.2 of the U.B.C. to redesign my teansverse reinforcement.
Section 1809.5.2.2 then send me to section 1921.4.4.1 since my ties are
rectangular. Using formula 21-4 and setting the fallowing values:
#3 ties Area-2x.11=.22
f'c-2500 psi
I get 5.6 " o.c. which I think is too close.  Can I used 1.33 factor to
increase my spacing?
It this calc. correct or I am missing something?
Where I can find reference about pile (pier) design ?
Any Historycal/technical respond about this subject will be greatly
 F. Duarte, EIT
Francisco Duarte
Lea and Sung Engineering, Inc.
Tel: 1-510-887-4086
Fax: 1-510-887-3019