HomeMy WebLinkAboutMS 16-01; PACIFIC WIND; GEOTECHNICAL REPORT UPDATE, PROPOSED PACIFIC WIND MULTI-FAMILY RESIDENTIAL DEVELOPMENT CARLSBAD, CALIFORNIA; 2021-06-17June 17, 2021
Harding Street Neighbors, LP Project No. 33090.15
14211 Yorba Street, Suite 200
Tustin, California 92780
Attention: Mr. Todd Cottle
Subject: Geotechnical Report Update, Proposed Pacific Wind Multi-Family Residential
Development, Carlsbad, California.
At your request we are providing this letter to update our previous geotechnical
investigation (LOR, 2014) with respect to the currently proposed development as shown
on the plans provided (Bassenian Lagoni, 2018) and current building code requirements
(2019 CBC).
On June 15, 2021, our project engineer went to the site to review the existing site
conditions. The site remains in essentially the same condition as previously reported (LOR,
2014).
The currently proposed development is similar to that previously reported (LOR, 2014).
However, a slightly smaller project area is currently proposed. Four parcels within the
northern portion of the original project are no longer included within the project.
It is the opinion of this firm that our previous geotechnical investigation conducted for the
property in addition to the information provided below, is considered appropriate for the
design and construction of the currently proposed project.
Design requirements for structures can be found within Chapter 16 of the 2019 California
Building Code (CBC) based on building type, use and/or occupancy. The classification of
use and occupancy of all proposed structures at the site, and thus the design
requirements, shall be the responsibility of the structural engineer and the building official.
For structures at the site to be designed in accordance with the provisions of Chapter 16,
the subject site specific criteria is provided below:
6121 Quail Valley Court • Riverside, CA 92507 • (951) 653-1760 • (951) 653-1741 (Fax)• www.lorgeo.com
Harding Street Neighbors, LP
June 17, 2021
Project No. 33090.15
Chapter 20 of the ASCE 7-16 defines six possible site classes for earth materials that
underlie any given site. Bedrock is assigned one of three of these six site classes and
these are: A, B, or C. Soil is assigned as C, D, E, or F. Per ASCE 7-16, Site Class A and
Site Class B shall be measured on-site or estimated by a geotechnical engineer,
engineering geologist or seismologist for competent rock with moderate fracturing and
weathering. Site Class A and Site Class B shall not be used if more than 10 feet of soil is
between the rock surface and bottom of the spread footing or mat foundation. Site Class
C can be used for very dense soil and soft rock with N values greater than 50 blows per
foot. Site Class D can be used for stiff soil with N values ranging from 15 to 50 blows per
foot. Site Class E is for soft clay soils with N values less than 15 blows per foot. Our
previous investigation, mapping by others, and our experience in the site region indicates
that the materials beneath the site are considered Site Class D stiff soils.
CBC Earthquake Design Summary
As determined in the previous section, earthquake design criteria have been formulated
for the site. However, these values should be reviewed and the final design should be
performed by a qualified structural engineer familiar with the region. Our design values are
attached.
We trust this information is as requested. Should you have any questions, please do not
hesitate to contact this office. We look forward to providing additional geotechnical services
for you on this very important project.
Respectfully submitted,
LOR Geotechnical Group, Inc.
P. Leuer, GE 2030
ent
AAT:JPL/ss
Attachment: Seismic Design Spectra
Distribution: Addressee (2) and via email todd@c-cdev.com
2
LOR GEOTECHNICAL GROUP, INC.
REFERENCES
American Society of Civil Engineers, 2016, Minimum Design Load for Buildings and Other
Structures, ASCE 7-16.
Bassenian Lagoni, 2018, Information Site Plan, Pacific Wind Apartments, Carlsbad,
California, dated July 27, 2018.
California Building Standards Commission and International Conference of Building
Officials, 2019, California Building Code, 2019 Edition.
LOR Geotechnical Group, Inc., 2014, Preliminary Geotechnical Investigation, Proposed
Multi-Family Residential Project, Carlsbad Apartments, APN’s 204-292-01, -02, -10 through
-14, -16 through -22, 204-291-14, -16, -17 and -19 through -27, Carlsbad, California,
Project No. 33090.1, dated July 31, 2014.
3
LOR GEOTECHNICAL GROUP, INC.
Project:Pacific Wind Apartments
Project Number:33090.14
Client:Harding Street Neighbors, LP
Site Lat/Long:33.1535 / -117.3384
Controlling Seismic Source:
REFERENCE NOTATION VALUE REFERENCE NOTATION VALUE
Site Class C, D, D default, or E Fv (Table 11.4-2)[Used for General Spectrum]Fv 1.9
Site Class D - Table 11.4-1 Fa 1.1 Design Maps Ss 1.069
Site Class D - 21.3(ii)Fv 2.5 Design Maps S1 0.387
0.2*(SD1/SDS)T0 0.129 Equation 11.4-1 - FA*SS SMS 1.1464*
SD1/SDS TS 0.646 Equation 11.4-3 - 2/3*SMS SDS 0.764*
Fundamental Period (12.8.2)T Period Design Maps PGA 0.471
Seismic Design Maps or Fig 22-14 TL 8 Table 11.8-1 FPGA 1.1
Equation 11.4-4 - 2/3*SM1 SD1 0.4936*Equation 11.8-1 - FPGA*PGA PGAM 0.532*
Equation 11.4-2 - FV*S1 SM1 0.7403*Section 21.5.3 80% of PGAM 0.425
Design Maps CRS 0.894
Design Maps CR1 0.905
Cr - At Perods <=0.2, Cr=CRS CRS 0.894 Cr - At Periods between 0.2 and 1.0 Period Cr
use trendline formula to complete 0.200 0.894
Cr - At Periods >=1.0, Cr=CR1 CR1 0.905 0.300 0.895
0.400 0.897
0.500 0.898
0.600 0.900
0.680 0.901
1.000 0.905
* Code based design value. See accompanying data for Site Specific Design values.Mapped values from
RISK COEFFICIENT
D measured
https://seismicmaps.org/
Newport Inglewood-Rose Canyon
LOR GEOTECHNICAL GROUP, INC.
Project No:33090.14
0.010 0.547 0.511 1.19 0.608
0.100 0.948 0.896 1.19 1.066
0.200 1.281 1.216 1.20 1.459
0.300 1.412 1.314 1.22 1.603
0.500 1.312 1.211 1.23 1.490
0.750 1.043 0.956 1.24 1.185
1.000 0.843 0.771 1.24 0.956 1 Data Sources:
2.000 0.440 0.399 1.24 0.495
3.000 0.281 0.255 1.25 0.319
4.000 0.197 0.178 1.25 0.223
5.000 0.147 0.133 1.26 0.168 2 Shahi-Baker RotD100/RotD50 Factors (2014)
0.547
NO
PROBABILISTIC SPECTRA1
2% in 50 year Exceedence
Probabilistic PGA:
Is Probabilistic Sa(max)<1.2Fa?
Period UGHM RTHM Max Directional
Scale Factor2
Probabilistic
MCE
https://earthquake.usgs.gov/hazards/interactive/
https://earthquake.usgs.gov/designmaps/rtgm/
0.00
0.50
1.00
1.50
2.00
0.000 1.000 2.000 3.000 4.000 5.000Acceleration (g)Period (seconds)
PROBABILISTIC MCER
SPECTRAL RESPONSE ACCELERATIONS
UGHM
RTHM
Probabilistic MCER
LOR GEOTECHNICAL GROUP, INC.
Controlling Source: Newport Inglewood-Rose Canyon
NO
Project No:33090.14
0.010 0.849 1.19 1.010 1.010
0.020 0.855 1.19 1.017 1.017
0.030 0.868 1.19 1.033 1.033
0.050 0.917 1.19 1.091 1.091
0.075 1.086 1.19 1.293 1.293 NO
0.100 1.282 1.19 1.525 1.525 N/A
0.150 1.558 1.20 1.870 1.870 Deterministic PGA:0.849
0.200 1.745 1.20 2.094 2.094 YES
0.250 1.895 1.21 2.293 2.293
0.300 1.978 1.22 2.414 2.414
0.400 2.013 1.23 2.476 2.476
0.500 1.951 1.23 2.400 2.400
0.750 1.605 1.24 1.990 1.990
1.000 1.349 1.24 1.673 1.673
1.500 0.944 1.24 1.171 1.171
2.000 0.702 1.24 0.870 0.870
3.000 0.458 1.25 0.573 0.573
4.000 0.303 1.25 0.378 0.378
5.000 0.215 1.26 0.271 0.271
DETERMINISTIC SPECTRUM
Largest Amplitudes of Ground Motions Considering All Sources Calculated using Weighted Mean of Attenuation Equations1
Is Probabilistic Sa(max)<1.2Fa?
Section 21.2.2
Scaling Factor
Applied
Is Determinstic Sa(max)<1.5*Fa?
Section 21.2.2 Scaling Factor:
Is Deterministic PGA >=FPGA*0.5?
2 Shahi-Baker RotD100/RotD50 Factors
(2014)
1 NGAWest 2 GMPE worksheet and
Uniform California Earthquake Rupture
Forecast, Version 3 (UCERF3) - Time
Dependent Model
Period
Deterministic PSa
Median + 1.σ for 5%
Damping
Max Directional Scale
Factor2 Deterministic MCE
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0.000 1.000 2.000 3.000 4.000 5.000Acceleration (g)Period (seconds)
DETERMINISTIC MCER
SPECTRAL RESPONSE ACCELERATIONS Deterministic
MCER
LOR GEOTECHNICAL GROUP, INC.
0.010 0.608 1.010 0.608 0.405 0.005 0.323 0.259
0.100 1.066 1.525 1.066 0.711 0.010 0.341 0.273
0.200 1.459 2.094 1.459 0.973 0.020 0.377 0.301
0.300 1.603 2.414 1.603 1.069 0.030 0.412 0.330
0.500 1.490 2.400 1.490 0.993 0.050 0.483 0.387
0.750 1.185 1.990 1.185 0.790 0.060 0.519 0.415
1.000 0.956 1.673 0.956 0.637 0.075 0.572 0.458
2.000 0.495 0.870 0.495 0.330 0.090 0.625 0.500
3.000 0.319 0.573 0.319 0.213 0.100 0.661 0.529
4.000 0.223 0.378 0.223 0.148 0.110 0.696 0.557
5.000 0.168 0.271 0.168 0.112 0.120 0.732 0.585
0.136 0.764 0.611
0.150 0.764 0.611
0.160 0.764 0.611
0.170 0.764 0.611
0.180 0.764 0.611
0.200 0.764 0.611
Calculated Design 0.250 0.764 0.611
Value Value 0.300 0.764 0.611
SDS:0.962 0.962 0.400 0.764 0.611
SD1:0.660 0.660 0.500 0.764 0.611
SMS:1.443 1.443 0.600 0.764 0.611
SM1:0.990 0.990 0.640 0.764 0.611
Site Specific PGAm:0.547 0.547 0.750 0.658 0.526
Site Class:0.850 0.581 0.465
0.900 0.548 0.439
Seismic Design Category - Short*D 0.950 0.520 0.416
Seismic Design Category - 1s*D 1.000 0.494 0.395
* Risk Categories I, II, or III 1.500 0.329 0.263
2.000 0.247 0.197
3.000 0.165 0.132
4.000 0.123 0.099
5.000 0.099 0.079
Project No:33090.14
SITE SPECIFIC SPECTRA
Period Probabilistic
MCE
Deterministic
MCE
Site-Specific
MCE Period
ASCE 7-16: Section 21.4
Design Response
Spectrum (Sa)
ASCE 7 SECTION 11.4.6
General Spectrum 80% General
Response Spectrum
D measured
Site Specific
LOR GEOTECHNICAL GROUP, INC.
33090.14Project No:
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0.000 1.000 2.000 3.000 4.000 5.000Acceleration (g)Period (seconds)
SPECTRAL RESPONSE ACCELERATIONS Probabilistic MCE
Deterministic MCE
Site-Specific MCE
Design Response Spectrum
ASCE 7 Section 11.4.6 General Spectrum
80% General Response Spectrum
LOR GEOTECHNICAL GROUP, INC.