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3/6/2018
1
Seismic Design of BuildingsGeotechnical Aspects
Jean Louis Locsin January 27, 2018
Outline
Introduction
Quick Review
Spectral Acceleration
Hazard Maps and Parameters
Site Effects
Procedures
Building Codes
General Procedure
Site-Specific Procedure
Seismic Design Category
Impacts on Design
Conclusions and Closing Remarks
Outline
Objectives
► What are the Relevant Geotechnical Seismic Design
Parameters that Impact Building Design
► How to Determine the Relevant Seismic Design
Parameters
► What does Seismic Design Category
Mean for Your Project
Objectives Earthquake Hazards
Earthquake
Structural Damage
Ground Failure
Fire
Tsunami
e.g. San Francisco Earthquake,1906
e.g., Niigata Earthquake, Japan, 1964
e.g., Northridge Earthquake, CA, 1994
e.g., Indian Ocean Earthquake, 2004
(Photo from Engineering Research Center Library, UC Berkeley.)
(Photo by Robert A. Eplett, FEMA Photo Library.)
(Photo by H. D. Chadwick, US Archiv ARCWEB.)
(Photo by Philip A. McDaniel, U.S. Navy photo.)
Earthquake Hazards
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2
Japan Earthquake
• Friday, March 11, 2011 at 2:46 pm local time
• Near the East Coast of Honshu, Depth 32 km (19.9 miles) below sea level
• Magnitude 9.0
From USGS and Japan Building Research Institute
Epicentral distance: 177 km ≈ 110 miles
0.92 g
0.74 g
0.65 g
2011 Japan Earthquake Japan Earthquake
U.S. Air Force photo/Tech. Sgt. DeNoris A. Mickle (Wikimedia)
This photo was taken on April 12, 2011 in Asahigaoka 1 Chome, Onagawa-cho, Miyagi Prefecture, Japan.
By Daisuke TSUDA, Flickr, (CC BY-SA 2.0)
Japan Earthquake
3/6/2018
3
The Current Practice in Seismic Design
Seismic Hazard Site Effects
Design Response Spectrum (SDS & SD1) Risk Category
(I, II, III, or IV)
Seismic Design
Category
Structural Fire ProtectionOther
Non-Structural
© Haley & Aldrich, Inc. 2018
Current Practice in Seismic Design Codes & Standards
• 9th Edition of the Massachusetts Building Code
• International Building Code (IBC) 2015
• ASCE 7-10 – Minimum Design Loads for Buildings and Other
Structures
Spectral Acceleration
Period, T, (sec.)
Sp
ectr
al
Acc
eler
ati
on
(g
)
Maximum Response
Sa
Sa
Tf
Tf
Earthquake Excitation
Accelerometer
Single Degree-of-Freedom Mass
PGA
PGA
PGA
© Haley & Aldrich, Inc. 2018
Spectral Acceleration & Response Spectrum
Seismic Hazard Site Effects
Design Response Spectrum (SDS & SD1) Risk Category
(I, II, III, or IV)
Seismic Design
Category
Structural Fire ProtectionOther
Non-Structural
The Current Practice in Seismic Design
© Haley & Aldrich, Inc. 2011
3/6/2018
4
Seismic Hazard
• USGS Mapped or Code Tabulated Spectral Accelerations (0.2 and 1.0 s)
• 2% Probability of Exceedance in 50 years (return period of about 2500 years)
• Site Class B
• Risk-Targeted
Mapped Accelerations (ASCE 7-10 and IBC 2015)
Mapped Accelerations (ASCE 7-10 and IBC 2015)
Short Period 1 s Period
9th Edition of the Massachusetts Building Code
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5
9th Edition of the Massachusetts Building Code USGS Online Tool
USGS Online Tool
Seismic Hazard Site Effects
Design Response Spectrum (SDS & SD1) Risk Category
(I, II, III, or IV)
Seismic Design
Category
Structural Fire ProtectionOther
Non-Structural
The Current Practice in Seismic Design
© Haley & Aldrich, Inc. 2011
3/6/2018
6
Site EffectsExample:
1989 Loma Prieta Earthquake, ML = 7.0
At Treasure Island vs. Yerba Buena Island
~50 miles (80 km) from the epicenter
Treasure Island and Yerba Buena
By Telstar Logistics
Google Pro
Loma Prieta
Earthquake
Epicenter
Treasure Island
Yerba Buena Island
Site Effects Site EffectsLoma Prieta Earthquake, ML = 7.0
Map fro
m G
oo
gle
Pro
/ D
ata
fro
m P
roS
hake
Oakland
San Francisco
Site Effects
Rock
Site Effects
Rock
Fill
Young Bay
Mud
Medium Dense
Sand
Old Bay Mud
Fine Gravely Sand
Clay and Shale
Loma Prieta Earthquake, ML = 7.0
© Haley & Aldrich, Inc. 2011
Site Effects
Seismic Hazard Site Effects
Design Response Spectrum (SDS & SD1) Risk Category
(I, II, III, or IV)
Seismic Design
Category
Structural Fire ProtectionOther
Non-Structural
General Site-SpecificOR
The Current Practice in Seismic Design
© Haley & Aldrich, Inc. 2011
3/6/2018
7
General Procedure
Soil Columns
Period, T, (sec.)
Period, T, (sec.)
Averaged Soil
Properties
Rock
(Graph after Borcherdt, 1994)
Site Effects – General Procedure Site-Specific Procedure
Soil Columns
Site Response at
Foundation Level
OR
Rock
Earthquake Excitation(Graph after Borcherdt, 1994)
Site Effects – Site Specific
SDS & SD1 by General Procedure
SS
S1
Mapped
Acceleration
Parameters
From Seismic
Hazard Maps (MCER)
Site Effects – General Procedure SDS & SD1 by General Procedure
SS
S1
Mapped
Acceleration
Parameters
From Seismic
Hazard Maps (MCER)
0.2
sec.
1.0
sec.
Site Effects – General Procedure
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8
SDS & SD1 by General Procedure
SS x Fa
S1 x Fv
Mapped
Acceleration
Parameters
From Seismic
Hazard Maps (MCER)
Site
Effects
Amplification Factors
Function of
Site Class
Site Effects – General Procedure Site Class
From: International Building Code 2009 and ASCE 7-10
• ASCE 7-10 Table 20.3-1
Site Class
Site Class
• ASCE 7-10 Table 20.3-1
From: International Building Code 2009 and ASCE 7-10
Site Class
Total distance
traveled by
shear wave
(=100 ft)
Site Class
• ASCE 7-10 Table 20.3-1
From: International Building Code 2009 and ASCE 7-10
Site Class
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9
Total distance
traveled by
shear wave
(=100 ft)
Total travel time
for shear wave
to travel
through all
sublayers
Site Class
• ASCE 7-10 Table 20.3-1
From: International Building Code 2009 and ASCE 7-10
Site Class
Total distance
traveled by
shear wave
(=100 ft)
Total travel time
for shear wave
to travel
through all
sublayers
Average SPT N and Average Su are calculated in the
same way as Average vs.
Site Class
• ASCE 7-10 Table 20.3-1
From: International Building Code 2009 and ASCE 7-10
Site Class
Site Class – Site Investigations
• Conventional Methods – Standard Penetration Test (SPT N
Values) and Sampling
• Geophysical Methods – Cross-hole Testing, Seismic CPT
Measurements of Shear Wave Velocity, and Others
• Correlations – SPT N or Cone Resistance Correlated to Shear
Wave Velocity
Site Class – Site Investigations SDS & SD1 by General Procedure
SS x Fa
S1 x Fv
Mapped
Acceleration
Parameters
From Seismic
Hazard Maps (MCER)
Site
Effects
Amplification Factors
Function of
Site Class
Site Effects – General Procedure
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10
Site Effects – Site Coefficients Fa & Fv
From: International Building Code 2015
• IBC 2015
Site Effects – Site Coefficients
Hazard Maps give
Ss for Site Class B
Hazard Maps give
S1 for Site Class B
Site Effects – Site Coefficients Fa & Fv
From: International Building Code 2015
• IBC 2015
Site Effects – Site Coefficients
“Worse” than B
“Worse” than B
“Better” than B
“Better” than B
Site Effects – Site Coefficients Fa & Fv
From: International Building Code 2015
• IBC 2015
Site Effects – Site Coefficients
Boston
0.217
0.069
Site Effects – Site Coefficients Fa & Fv
From: International Building Code 2015
Seattle
1.366
0.529
• IBC 2015
Site Effects – Site Coefficients
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11
Boston
0.217
0.069
Site Effects – Site Coefficients Fa & Fv
From: International Building Code 2015
Seattle
1.366
0.529
• IBC 2015
Site Effects – Site Coefficients
i.e., by Site-Specific Analysis
SDS & SD1 by General Procedure
SS x Fa = SMS
S1 x Fv = SM1
Mapped
Acceleration
Parameters
From Seismic
Hazard Maps (MCER)
Site
Effects
Amplification Factors
Function of
Site Class
Adjusted
MCER
Accelerations
Site Effects – General Procedure
SDS & SD1 by General Procedure
SS x Fa x 2/3 = SDS
S1 x Fv x 2/3 = SD1
Mapped
Acceleration
Parameters
From Seismic
Hazard Maps (MCER)
Site
Effects
Amplification Factors
Function of
Site Class
Design
Accelerations
Two-Parameter Definition
of Generic Spectrum
Code
Reduction
Factor
Site Effects – General Procedure
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.5 1 1.5 2 2.5 3 3.5 4
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5% Damping
Spectrum for Site Class E
Spectrum for Site Class DSDS for E
SD1 for E
SD1 for D
SDS for D
Design Spectra by General Procedure
© Haley & Aldrich, Inc. 2018
BOSTON, MA
Design Spectra – General Procedure
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.5 1 1.5 2 2.5 3 3.5 4
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5% Damping
Spectrum for Site Class E
Spectrum for Site Class D
Spectrum for Site Class C
Spectrum for Site Class B
Design Spectra by General Procedure
© Haley & Aldrich, Inc. 2018
BOSTON, MA
Design Spectra – General Procedure Site-Specific Response Analysis
Where Required?
• Site Class F – one or more of the following
• Liquefiable soils, quick & highly sensitive clays, collapsible weakly cemented soils.
• >10 ft of Peats and/or highly organic clays.
• Very high plasticity clays (>25 ft with PI>75).
• >120 ft of soft/medium stiff clays.
• If not required, sometimes performed to reduce design spectral accelerations (but with Code limitation)
Site-Specific Response Analysis
Example of Site Class F
• Liquefiable soils
Christchurch 2011; Photo by: Tim Musson
Niigata 1964; Photo from Engineering Research
Center Library, UC Berkeley
http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en
Example of Site Class F MA Building Code – Liquefaction Screening Plots
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Simplified Liquefaction Analyses
• Youd & Idriss (2001), Boulanger & Idriss (2014), etc.
• Demand
• Peak horizontal acceleration (amax) – ASCE 7-10, use MCEG (i.e., not adjusted for risk)
• Resistance
• SPT N-values (usual data)
• Fines Content
Site-Specific Response Analysis
Fill
Organics
Clay
Till
Rock
Ground Surface
Vs-Fill
Vs-Org.
Vs-Clay
Vs-Till
Vs-Rock
1-D
Analysis
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis
Rock Motion (a vs. t), MCE
Fill
Organics
Clay
Till
Rock
Ground Surface
Vs-Fill
Vs-Org.
Vs-Clay
Vs-Till
Vs-Rock
1-D
Analysis
Site-Specific Response Analysis
-0.20
-0.10
0.00
0.10
0.20
0 5 10 15 20 25 30 35 40
Ac
ce
lera
tio
n,
g
Time, sec
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis
Rock Motion (a vs. t), MCE
Fill
Organics
Clay
Till
Rock
Ground Surface
Vs-Fill
Vs-Org.
Vs-Clay
Vs-Till
Vs-Rock
1-D
Analysis
Site-Specific Response Analysis
-0.20
-0.10
0.00
0.10
0.20
0 5 10 15 20 25 30 35 40
Ac
ce
lera
tio
n,
g
Time, sec
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis
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14
Rock Motion (a vs. t), MCE
Fill
Organics
Clay
Till
Rock
Ground Surface
Vs-Fill
Vs-Org.
Vs-Clay
Vs-Till
Vs-Rock
Ground Surface Motion
1-D
Analysis
Site-Specific Response Analysis
-0.20
-0.10
0.00
0.10
0.20
0 5 10 15 20 25 30 35 40
Ac
ce
lera
tio
n, g
Time, sec
-0.20
-0.10
0.00
0.10
0.20
0 5 10 15 20 25 30 35 40
Ac
ce
lera
tio
n, g
Time, sec
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis
Rock Motion (a vs. t), MCE
Fill
Organics
Clay
Till
Rock
Ground Surface
Vs-Fill
Vs-Org.
Vs-Clay
Vs-Till
Vs-Rock
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5 4
Sp
ec
tra
l Ac
ce
lera
tio
n, g
Period, sec
5% Damping
Ground Surface Motion
Response
Spectrum at
Ground
Surface1-D
Analysis
Site-Specific Response Analysis
-0.20
-0.10
0.00
0.10
0.20
0 5 10 15 20 25 30 35 40
Ac
ce
lera
tio
n, g
Time, sec
-0.20
-0.10
0.00
0.10
0.20
0 5 10 15 20 25 30 35 40
Ac
ce
lera
tio
n, g
Time, sec
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis
Site-Specific Response AnalysisMCE Rock Spectra & Site Effects
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5 4
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
Spectra of the MCE Rock
Motions
5%
Damping
Spectra of Computed MCE
Motions
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis Site-Specific Response Analysis
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5 4
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5%
Damping
Mean Plus 1SD of 2/3 MCE Computed
Spectra
2/3 Spectra of Computed MCE
Motions
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis
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Site-Specific Response AnalysisDesign Spectrum
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5 4
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5% Damping
Mean Plus 1SD of 2/3 MCE
Computed Spectra
Recommended Design Spectrum
80% of Spectrum for Site
Class E
Spectrum for Site Class E
© Haley & Aldrich, Inc. 2011
Site-Specific Response Analysis Design Impacts of Seismic Code Provisions
Seismic Hazard Site Effects
Design Response Spectrum (SDS & SD1) Risk Category
(I, II, III, or IV)
Seismic Design
Category
Structural Fire ProtectionOther
Non-Structural
© Haley & Aldrich, Inc. 2011
According to Code: if different between SDS and SD1, take the more severe seismic design category irrespective of fundamental period of the structure.
Seismic Design Category
SDS Ranges
SD1 Ranges
Tables From: International Building Code 2015
• IBC 2015
Seismic Design Category
According to Code: if different between SDS and SD1, take the more severe seismic design category irrespective of fundamental period of the structure.
Seismic Design Category
SDS Ranges
SD1 Ranges
Tables From: International Building Code 2015
• IBC 2015
Seismic Design Category
Low hazard to
human life in
event of failure,
e.g.,
agricultural
facilities, minor
storage
facilities
3/6/2018
16
According to Code: if different between SDS and SD1, take the more severe seismic design category irrespective of fundamental period of the structure.
Seismic Design Category
SDS Ranges
SD1 Ranges
Tables From: International Building Code 2015
• IBC 2015
Seismic Design Category
Substantial
hazard to
human life in
event of failure,
e.g., public
assembly,
education
facilities,
certain public
utility facilities.
According to Code: if different between SDS and SD1, take the more severe seismic design category irrespective of fundamental period of the structure.
Seismic Design Category
SDS Ranges
SD1 Ranges
Tables From: International Building Code 2015
• IBC 2015
Seismic Design Category
Essential
Facilities,
e.g.,emergency
treatment
facilities,
emergency
response
centers, etc.
Occupancy Category and Performance Level
From: 2009 NEHRP RECOMMENDED SEISMIC PROVISIONS FOR NEW BUILDINGS AND
OTHER STRUCTURES: PART 2, COMMENTARY TO ASCE/SEI 7-05
Occupancy (or Risk) Category and Performance Level
From: 2009 NEHRP RECOMMENDED SEISMIC PROVISIONS FOR NEW BUILDINGS AND
OTHER STRUCTURES: PART 2, COMMENTARY TO ASCE/SEI 7-05
Code
Occupancy Category and Performance LevelOccupancy (or Risk) Category and Performance Level
3/6/2018
17
From: 2009 NEHRP RECOMMENDED SEISMIC PROVISIONS FOR NEW BUILDINGS AND
OTHER STRUCTURES: PART 2, COMMENTARY TO ASCE/SEI 7-05
Increasing Performance Level
Code
Occupancy Category and Performance LevelOccupancy (or Risk) Category and Performance Level
E
D
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.5 1 1.5
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5% Damping
Seismic Design Category
BOSTON, MA
© Haley & Aldrich, Inc. 2018
Seismic Design Category
E
D
0.167
0.33
0.5
0.067
0.133
0.2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.5 1 1.5
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5% Damping
SDS
SD1
SEISMIC DESIGN
CATEGORY
BASED ON SDS
SEISMIC DESIGN
CATEGORY
BASED ON SD1
RISK CAT.
I OR II, III
C
B
RISK CAT.
IV
D
B
C
B
C
B
B
D
C
B
RISK CAT.
I OR II, IIIRISK CAT.
IV
Seismic Design Category
BOSTON, MA
© Haley & Aldrich, Inc. 2018
Seismic Design Category
Therefore, for Boston Risk Cat. I or II, III:
• Site Class E leads to SDC C
• Site Class D leads to SDC B
E
D
0.167
0.33
0.5
0.067
0.133
0.2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.5 1 1.5
Sp
ectr
al A
ccele
rati
on
, g
Period, sec
5% Damping
SDS
SD1
SEISMIC DESIGN
CATEGORY
BASED ON SDS
SEISMIC DESIGN
CATEGORY
BASED ON SD1
RISK CAT.
I OR II, III
C
B
RISK CAT.
IV
D
B
C
B
C
B
B
D
C
B
RISK CAT.
I OR II, IIIRISK CAT.
IV
Therefore, for Boston Risk Cat. IV:
• Site Class E leads to SDC D
• Site Class D leads to SDC C
Seismic Design Category
BOSTON, MA
© Haley & Aldrich, Inc. 2018
Seismic Design Category
3/6/2018
18
Design Impacts of Seismic Code Provisions
Seismic Hazard Site Effects
Design Response Spectrum (SDS & SD1) Risk Category
(I, II, III, or IV)
Seismic Design
Category
Structural Fire ProtectionOther
Non-Structural
© Haley & Aldrich, Inc. 2011
Impacts on Structural Design Example
• Proposed Building, 10 story, ~400,000 sq. ft.
• Initial Site Class from Borings/SPT was E (SDC C)
• Cross-hole Shear Wave Measurements Performed at Site
• Average Shear Wave Velocity > 600 ft/s, Site Class D (SDC B)
• Cost Savings on Steel ~$2.50/sq. ft. (total ~$1.1M!!)
Impacts on Structural Design Example
Impacts on Fire Protection System Example
• IBC 2015
• 9th Edition MA Building Code – High-Rise Building defined as a
building more than 70 ft in height above grade plane.
• Our Experience: Cost of Water Tank between $100-200k Plus
Program Issues
Impacts on Fire Protection System Impacts on Other Non-Structural Components
• Architectural, Mechanical, Electrical & Other Non-Structural
Systems and Components
FEMA News Photo
FEMA News Photo
FEMA News Photo
Impacts on Other Non-Structural Components
3/6/2018
19
Conclusions
• Code Seismic Provisions (esp. SDC) Can Have Significant Cost
Impacts on a Project
• Site-Specific Response Analysis May Reduce Seismic Loads but
Not Necessarily Improve SDC
• Good Field Investigation Program May Provide Significant Cost
Benefits
Conclusions Closing Remarks
► Relevant Geotechnical Seismic Design Parameters
that Impact Building Design
► How to Determine Relevant Seismic Design
Parameters
► What Seismic Design Category Means for Your
Project
Closing Remarks
Thank you!Any questions?