Seismic Design of Buildings Geotechnical Aspects ......Seismic Design of Buildings Geotechnical Aspects Jean Louis Locsin January 27, 2018 Outline Introduction Quick Review Spectral

3/6/2018

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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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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


Spectral Acceleration & Response Spectrum



(I, II, III, or IV)

Seismic Design

Category


Non-Structural



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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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9th Edition of the Massachusetts Building Code USGS Online Tool

USGS Online Tool



(I, II, III, or IV)

Seismic Design

Category


Non-Structural



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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


Site Effects



(I, II, III, or IV)

Seismic Design

Category


Non-Structural

General Site-SpecificOR



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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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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


Site Class

Total distance

traveled by

shear wave

(=100 ft)

Site Class

• ASCE 7-10 Table 20.3-1


Site Class

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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


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


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


Function of

Site Class


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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



• IBC 2015


“Worse” than B

“Worse” than B

“Better” than B

“Better” than B



• IBC 2015


Boston

0.217

0.069



Seattle

1.366

0.529

• IBC 2015


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Boston

0.217

0.069



Seattle

1.366

0.529

• IBC 2015


i.e., by Site-Specific Analysis


SS x Fa = SMS

S1 x Fv = SM1

Mapped

Acceleration

Parameters

From Seismic

Hazard Maps (MCER)

Site

Effects


Function of

Site Class

Adjusted

MCER

Accelerations



SS x Fa x 2/3 = SDS

S1 x Fv x 2/3 = SD1

Mapped

Acceleration

Parameters

From Seismic

Hazard Maps (MCER)

Site

Effects


Function of

Site Class

Design

Accelerations

Two-Parameter Definition

of Generic Spectrum

Code

Reduction

Factor


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


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 D

Spectrum for Site Class C

Spectrum for Site Class B

Design Spectra by General Procedure


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


Fill

Organics

Clay

Till

Rock

Ground Surface

Vs-Fill

Vs-Org.

Vs-Clay

Vs-Till

Vs-Rock

1-D

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


-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




Fill

Organics

Clay

Till

Rock

Ground Surface

Vs-Fill

Vs-Org.

Vs-Clay

Vs-Till

Vs-Rock

1-D

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



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Fill

Organics

Clay

Till

Rock

Ground Surface

Vs-Fill

Vs-Org.

Vs-Clay

Vs-Till

Vs-Rock

Ground Surface Motion

1-D

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




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


-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



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


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



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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



Site-Specific Response Analysis Design Impacts of Seismic Code Provisions



(I, II, III, or IV)

Seismic Design

Category


Non-Structural


According to Code: if different between SDS and SD1, take the more severe seismic design category irrespective of fundamental period of the structure.


SDS Ranges

SD1 Ranges

Tables From: International Building Code 2015

• IBC 2015




SDS Ranges

SD1 Ranges


• IBC 2015


Low hazard to

human life in

event of failure,

e.g.,

agricultural

facilities, minor

storage

facilities

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SDS Ranges

SD1 Ranges


• IBC 2015


Substantial

hazard to

human life in

event of failure,

e.g., public

assembly,

education

facilities,

certain public

utility facilities.



SDS Ranges

SD1 Ranges


• IBC 2015


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



Code

Occupancy Category and Performance LevelOccupancy (or Risk) Category and Performance Level

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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


BOSTON, MA



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


BOSTON, MA



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


BOSTON, MA



3/6/2018

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Design Impacts of Seismic Code Provisions



(I, II, III, or IV)

Seismic Design

Category


Non-Structural


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

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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?

Documents

Seismic Design of Buildings Geotechnical Aspects ......Seismic Design of Buildings Geotechnical Aspects Jean Louis Locsin January 27, 2018 Outline Introduction Quick Review Spectral