HomeMy WebLinkAboutSDP 01-17; LA COSTA GREENS MULTI FAMILY HOUSING; Site Development Plan (SDP)Geotechnics
Incorporated
San Diego
ElCentro
Riverside
July 2, 2009
Wave Crest Resorts III, LLC
829 Second Sfreet, Suite A
Encinitas, Califomia 92024
Attention: Mr. John Yeakey
Project No. 0703-002-01
Document No. 09-0350
SUBJECT:
Reference:
Gentlemen:
SUPPLEMENTAL SEISMIC WALL DESIGN PARAMETERS
Hilton Carlsbad Beach Resort and Spa
Carlsbad, California
Geotechnics Incorporated (2009). Geotechnical Investigation, Hilton Carlsbad
Beach Resort and Spa, Carlsbad, California, Project No. 0703-002-01, Document
No. 09-0206, dated April 24.
In accordance with the request of the project structural engineer, we are providing herein
supplemental geotechnical parameters for seismic retaining wall design at the subject site. In
Section 8.4.5 of the referenced report, we recommended a short-period spectral design
acceleration (SDS) of 0.890g. The associated design peak ground acceleration for the site per the
2007 California Building Code is taken as 40 percent of SDS or roughly 0.36g.
We recommend that seismic wall design be conducted using the Mononabe-Okabe solution
which incorporates a pseudo-static horizontal load. It should be noted that the pseudo-static load
is not directly related to PGA. A "repeatable" or cyclic load of V2 or ^/s of the PGA (0.14g,
0.18g or 0.24g in this case) is often used by engineers for pseudo-static seismic wall design. We
have developed geotechnical parameters for seismic retaining wall design based on pseudo-static
loads of 0.14g, 0.18g and 0.24g. The results of our analyses are presented graphically in the
attached Figures 1 through 3. The choice of the appropriate pseudo-static load is left to the
discretion of the project structural engineer.
9245 Activity Road Suite 103 • San Diego, California 92126
Phone (858) 536-1000 • Fax (858) 836-8311
WAVE CREST RESORTS III, LLC PROJECT NO. 0703-002-01
JULY 2, 2009 DOCUMENT NO. 09-0350
PAGE 2
The pseudo-static seismic load may be idealized as an inverted triangular pressure distribution
with the resultant acting at a height of 0.6H from the base of the wall. Note that in the
Mononabe-Okabe solution, the seismic load is superposed on the classical triangular active
pressure wedge. For restrained building walls which are not free to yield at least '/i percent of
the wall height, we recommend that the equivalent seismic pressures (ye) shown in Figures 1
through 3 be added to the at-rest earth pressures provided in Section 8.6.1 of the referenced
geotechnical investigation (Geotechnics, 2009).
We appreciate this opportunity to provide professional services. If you have any questions or
comments regarding the information provided, please do not hesitate to contact us.
GEOTECHNICS INCORPORATED
Matthew A. Fagan, P.E. 57248 '"^^^^i^^^ Anthony F. Belfast, P.E. 40333
Project Engineer *^ Principal Engineer
Disfribution: (4) Addressee, Mr. John Yeakey
(1) DCI Engineers, Mr. John Deck (ideck(a;dci-engineers.com)
Geotechnics Incorporated •
INPUT PARAMETERS CALCULATED PARAMETERS
Unit Weight of Soii [PCF]
Backfill Soil Friction Angle (ij)) [°]:
Wall Friction Angle (5) ["]:
Soil Backfill Angle (a) [°]:
Wall Batter Angle ((3) ["]:
Horizontal Acceleration (Kh) [g's]:
Vertical Acceleration (K„) [g's]:
125
32
20
90
0.14
0.00
Active Pressure Coefficient (Kg):
Equivalent Fluid Pressure (ya):
Seismic Pressure Coefficient (Kae):
Equivalent Fluid Pressure (vae):
Equivalent Seismic Pressure (ve):
0.28
34
0.37
46
12
Active Pressure Resultant: Fa = 1/2 -/a H
Earthquake Pressure Resultant: Fg = 1/2 ye
Horizontal Component of Active Pressure Resultant Fah = Fg cos(5+90-p)
Horizontal Component of Seismic Pressure Resultant Feh = Fe cos(5+90-|3)
Granular
Backfill
-4—
YaH
Fah
H/3
0.6 H
Geotechnics
Incorporated
SEISMIC WALL LOADS (K^ ~ 0.14g)
Project No. 0703-002-01
Document No. 09-0350
FIGURE 1
INPUT PARAMETERS CALCULATED PARAMETERS
Unit Weight of Soil [PCF]
Backfill Soil Friction Angle (())) [°]:
Wall Friction Angle (5) [°]:
Soil Backfill Angle (a) [°]:
Wall Batter Angle (P) [°]:
Horizontal Acceleration (Kh) [g's]:
Vertical Acceleration (K^,) [g's]:
125
32
20
90
0.18
0.00
Active Pressure Coefficient (Kg):
Equivalent Fluid Pressure (ya):
Seismic Pressure Coefficient (Kge):
Equivalent Fluid Pressure (yae):
Equivalent Seismic Pressure (ye):
0.28
34
0.41
51
16
Active Pressure Resultant: Fa = 1/2 ya H
Earthquake Pressure Resultant: Fe = 1/2 ye
Horizontal Component of Active Pressure Resultant Fgh = Fa cos(6+90-p)
Horizontal Component of Seismic Pressure Resultant Feh = cos(5+90-p)
H
Granular
Backfill
Y <^
c=0
r
\ I
\ . t
a
Fah
\ \ \ \
YaH
YeH
Y.
H/3
0.6 H
Geotechnics
Incorporated
SEISMIC WALL LOADS (K^ ~ 0.18g)
Project No. 0703-002-01
Document No. 09-0350
FIGURE 2
INPUT PARAMETERS CALCULATED PARAMETERS
Unit Weight of Soil [PCF]
Backfill Soil Friction Angle (^) [°]:
Wall Friction Angle (6) [°]:
Soil Backfill Angle (a) [°]:
Wall Batter Angle (P) ["]:
Horizontal Acceleration (Kh) [g's]:
Vertical Acceleration (K,,) [g's]:
125
32
20
90
0.24
0.00
Active Pressure Coefficient (Kg):
Equivalent Fluid Pressure (ya):
Seismic Pressure Coefficient (Kge):
Equivalent Fluid Pressure (yae):
Equivalent Seismic Pressure (ye):
0.28
34
0.46
58
23
Active Pressure Resultant: Fg = 1/2 ya H
Earthquake Pressure Resultant: Fe = 1/2 ye H^
Horizontal Component of Active Pressure Resultant Fgh = Fg cos(5+90-p)
Horizontal Component of Seismic Pressure Resultant Feh = Fe cos(6+90-p)
H
Granular
Backfill
y (f)
c=0
4-
a
Fah
YaH
H/3
YeH
0.6 H
G e ote c hni c s
Incorporated
SEISMIC WALL LOADS (K^, ~ 0.24g)
Project No. 0703-002-01
Document No. 09-0350
FIGURE 3