00 asce c whittaker 2

8/13/2019 00 ASCE c Whittaker 2

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Characterization of

Earthquake Ground Motion in

Andrew Whittaker, PhD, SEDepartment of Civil, Structural and Environmental Engineering

University at Buffalo

Nicolas Luco, PhDResearch Engineer

United States Geological Surveyo en,


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USGS Hazard Mapping Project ar e ersen

Steve Harmsen

FEMA-Funded BSSC Project 07 Charles Kircher (Chair)

Members from industry, academia, and government Messrs. Hooper, Holmes, Hamburger, Harris, Luco, Whittaker, among

Yin-Nan Huang

ASCE 7-10 Standard Ad-Hoc GM Committee

John Hooper (SSC Chair)

C.B. Crouse (TC1 Chair)


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Characterizing seismic hazard

ASCE/SEI 7-05 seismic design maps Development (site-specific procedure)

Java ground motion parameter calculator

ASCE/SEI 7-10 seismic design maps - Seismic design maps web application

Com arison of seismic desi n values

Summary of differences


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Response spectrum

Probabilistic seismic hazard analysis All possible sources and earthquakes

Ground motion attenuation relationshi s

ASCE 7-05: relationships available in 2002

ASCE 7-10: relationships available in 2008

NGA in the WUS

NGA-East and NGA-West 2 under way

Deterministic seismic hazard analysis Controllin earth uake source and distance e. . M8 15 km

Hazard analysis references Kramer (1996) and McGuire (2004)


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Res onse s ectrum

ASCE 7 reports ordinates at 0.2 and 1.0 second Bedrock; Vs,30 = 760 m/second (B/C boundary)

Adjust for soil type using Fa and Fv


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Response spectrum

Geometric mean (geomean) spectrum Maximum direction spectrum

0.3

0.4

0.5

Ac

c.

inFP

dir

ection

(g)

-0 5 -0 4 -0 3 -0 2 -0 1 0 0 1 0 2 0 3 0 4 0 50

0.1

0.2

. . . . . . . . . .

-0.3

-0.2

-0.1 Acc. in FNdirection (g)

-0.5

- .


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Response spectrum

Maximum direction spectrum ASCE 7-10

Use directly with Equivalent Lateral Force Procedure

Collapse Prevention is the target performance level r ru

ASCE 7-05

Use with response-history analysis

Use the maximum and minimum spectra recover thegeometric mean spectrum

One component per spectrum


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-

- .SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B


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Methodology from BSSC Project 97

Consistent with site-specific GM hazardanalysis procedure of Chapter 21 Probabilistic ground motion

2%-in-50 year (uniform hazard) GM

1.5 x median GM, but not < 1.5Faor 0.6Fv/ T

MCE GM = min (Prob. GM, Det. GM)

Mapped GMs computed by USGS in 2002


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From site-specific GM hazard analysis

procedure of Chapter 21 of ASCE 7-05 . . .

shall be taken as the spectral response accelerations represented by a 5 percentdamped acceleration response spectrum having a 2 percent probability of

exceedence within a 50-yr. period.


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procedure of Chapter 21 of ASCE 7-05 . . .

shall be taken as the spectral response accelerations represented by a 5 percentdamped acceleration response spectrum having a 2 percent probability of

exceedence within a 50-yr. period.

Probabilistic GM = uniform-hazard GM


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Site Class B/C boundary (Vs,30 = 760 m/s)


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from GM Hazard Curves

2% in 50yrs

Output of Probabilistic Seismic Hazard Analysis (PSHA)


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21.2.2 Deterministic MCE.The deterministic MCE response acceleration at eachprocedure of Chapter 21 of ASCE 7-05

per o s a e ca cu ate as percent o t e argest me an percent ampespectral response acceleration computed at that period for characteristic earthquakeson all known active faults within the region. the ordinates of the deterministic MCE

ground motion response spectrum shall not be taken as lower than the correspondingor nates o t e response spectrum eterm ne n accor ance w t g. . -


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21.2.2 Deterministic MCE.The deterministic MCE response acceleration at eachprocedure of Chapter 21 of ASCE 7-05

per o s a e ca cu ate as percent o t e argest me an percent ampespectral response acceleration computed at that period for characteristic earthquakeson all known active faults within the region. the ordinates of the deterministic MCE

ground motion response spectrum shall not be taken as lower than the correspondingor nates o t e response spectrum eterm ne n accor ance w t g. . -

Max (1.5 x median GM, 1.5Fa) for 0.2sMax 1.5 x median GM 0.6F for 1.0s


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USGS computed (but did not publish)

median (50th

-%ile) GM maps, e.g.,


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21.2.3 Site-Specific MCE:The site-specific MCE spectral response acceleration atprocedure of Chapter 21 of ASCE 7-05

, aM,from the probabilistic MCE of Section 21.2.1 and the deterministic MCE of Section21.2.2.

Recall - -.

Det. GM = max (1.5 x median GM, 1.5Faor 0.6Fv/T)


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21.2.3 Site-Specific MCE:The site-specific MCE spectral response acceleration atprocedure of Chapter 21 of ASCE 7-05

, aM,from the probabilistic MCE of Section 21.2.1 and the deterministic MCE of Section21.2.2. MCE GM = min (Prob. GM, Det. GM )

Recall - -.

Det. GM = max (1.5 x median GM, 1.5Faor 0.6Fv/T)


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-

FIGURE 22-1 MAXIMUM CONSIDERED EARTH UAKE MCE GROUND MOTION OF 0.2 SECSPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B


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http://earthquake.usgs.gov/hazards/design/download.php


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- R

FIGURE 22-1 MAXIMUM CONSIDERED EARTH UAKE MCE GROUND MOTION OF 0.2 SECSPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B


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Methodology from BSSC Project 07

-

Consistent with site-specific procedure Probabilistic ground motion

e o : n orm- azar x s oe c en

Method 2: Risk-targeted probabilistic GM directly

Deterministic ground motion 84th-%ile GM, but not < 1.5Faor 0.6Fv/ T

MCERGM = min (Prob. GM, Det. GM)

Mapped GMs computed by USGS in 2008


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21.2.1 Probabilistic Ground MotionMCE. The probabilistic MCE spectral responseprocedure of Chapter 21 of ASCE 7-10

horizontal response represented by a 5 percent damped acceleration response spectrum that isexpected to achieve a 1 percent probability of collapse within a 50-yr. period having a 2 percentprobability of exceedance within a 50-yr. period.

. . . e o : eac spec ra response per o or w c e acce era on s compu e ,ordinates of the probabilistic ground motion response spectrum shall be determined from iterativeintegration of a site-specific hazard curve with a lognormal probability density functionrepresenting the collapse fragility (i.e., probability of collapse as a function of spectral responseacceleration). The ordinate of the probabilistic ground-motion response spectrum at each period

shall achieve a 1 percent probability of collapse within a 50-yr. period for a collapse fragilityhaving (i) a 10 percent probability of collapse at said ordinate of the probabilistic ground-motionresponse spectrum and (ii) a logarithmic standard deviation values of 0.6.


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21.2.1 Probabilistic Ground MotionMCE. The probabilistic MCE spectral responseprocedure of Chapter 21 of ASCE 7-10

horizontal response represented by a 5 percent damped acceleration response spectrum that isexpected to achieve a 1 percent probability of collapse within a 50-yr. period having a 2 percentprobability of exceedance within a 50-yr. period.

. . . e o : eac spec ra response per o or w c e acce era on s compu e ,ordinates of the probabilistic ground motion response spectrum shall be determined from iterativeintegration of a site-specific hazard curve with a lognormal probability density functionrepresenting the collapse fragility (i.e., probability of collapse as a function of spectral responseacceleration). The ordinate of the probabilistic ground-motion response spectrum at each period

Probabilistic GM = Risk targeted GM

shall achieve a 1 percent probability of collapse within a 50-yr. period for a collapse fragilityhaving (i) a 10 percent probability of collapse at said ordinate of the probabilistic ground-motionresponse spectrum and (ii) a logarithmic standard deviation values of 0.6.


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Calculated iteratively by combining

Risk targetfrom Project 07

(e.g., from USGS)

defined by Project 07

1% probabilityof collapse

in 50 years

via the risk integral (e.g., ATC 3-06), i.e.,


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Estimate RTGM

Generate fragility curve as a function of RTGMtion

Integrate fragility and hazard curves to calculate riskn

loc

P[Collapse] in 50 yearsgive

No

=

For Yes

RTGM ca cu ate


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Generic fragility curves for the 1st iteration assuming


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GM hazard curves from USGS

Note: USGS values ofSA factored by 1.1 for. s an . or . s to

convert approx. to

maximum direction.


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HazardRisk Fragility


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rd

H

az

agility

F

Risk


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ard

H

a

ra

gility

Ris


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Note: RTGMs are capped by deterministic GMs toproduce MCERmaps in ASCE/SEI 7-10


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50N

40N

45N

35N

125W

65 W

N

0N

20W 115

W 110W 105W 100W 95W 90W 85

W 80W 75

W

70

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6

< 0.85


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50N

40N

45N

35N

125W

65W

25N

0N

20W 115

W 110W 105W 100W 95W 90W 85

W 80W 75

W

70

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6

> 1.15


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Probabilistic GMs = Risk targeted GMs

Risk targeted GMs calculated from GM hazard curves (from USGS for maps)

Building fragility curves (def. by Project 07)

Risk target (defined by Project 07)

- , RTGM = UHGM x Risk Coefficients

Risk Coefficient maps computed using USGS hazard curves

are included inASCE/SEI 7-10 Online Risk Coefficient calculator planned


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21.2.2 Deterministic Ground MotionMCE. The deterministic MCEspectralth-

procedure of Chapter 21 of ASCE 7-10

percent of the largest median 5 percent damped spectral response acceleration inthe direction of maximum horizontal response computed at that period the

ordinates of the deterministic ground motions response spectrum shall not be taken

accordance with Fig. 21.2-1,


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21.2.2 Deterministic Ground MotionMCE. The deterministic MCEspectralth-


percent of the largest median 5 percent damped spectral response acceleration inthe direction of maximum horizontal response computed at that period theordinates of the deterministic ground motions response spectrum shall not be taken

Deterministic GM =accordance with Fig. 21.2-1, max - e , . a or . s

max( 84th-%ile GM, 0.6Fv) for 1.0s

(a maximum direction GM, like probabilistic GM)


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USGS computed (but not yet published)

median (50

th

-%ile) GM maps, e.g.,


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Project 07 decision .

84th-%ile GMs = approx. 1.8 x median GMs

For maximum direction GMs, also factor by . .

1.3 for 1.0s

Since Fa=1 and Fv=1 for Site Class B,

Det. GM = max ( 1.1 x 1.8 x Med. GM, 1.5g) for 0.2s

Det. GM = max ( 1.3 x 1.8 x Med. GM, 0.6g) for 1.0s


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These intermediate maps are not included inASCE 7-10 but are in 2009 NEHRP Provisions


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R

procedure of Chapter 21 of ASCE 7-10 21.2.3 Site-Specific MCE R: The site-specific MCER spectral responseacce era on a any per o , aM, s a e a en as e esser o e spec raresponse accelerations from the probabilistic ground motionsMCE of Section21.2.1 and the deterministic ground motionsMCE of Section 21.2.2.

eca Probabilistic GM = Risk targeted GM

th-. , . a . v

Both are maximum direction GMs


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R


21.2.3 Site-Specific MCE R: The site-specific MCER spectral response


acce era on a any per o , aM, s a e a en as e esser o e spec raresponse accelerations from the probabilistic ground motionsMCE of Section21.2.1 and the deterministic ground motionsMCE of Section 21.2.2.

MCERGM = min (Prob. GM, Det. GM )

eca Probabilistic GM = Risk targeted GM

th-. , . a . v

Both are maximum direction GMs


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- .SPECTRAL RESPONSE ACCELERATION (5% OF CRITICAL DAMPING), SITE CLASS B


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http://earthquake.usgs.gov/designmaps/usapp


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http://earthquake.usgs.gov/designmaps/usapp


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34 city sites in the Continental United States

Selection of regions most at risk High seismic regions (Nor Cal, So Cal, PNW) Hi h o ulation areas of hi h moderate low seismic re ions

(Intermountain and CEUS)

Selection of city sites

Nearest USGS hazard grid point to center of city

Avera e re ional or national values

Weight seismic design value of associated county bymetropolitan area population

Assume default Soil Type (Site Class D)


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Map showing selected United States city sites (34) used to compareground motions (WUS faults shown with red lines)


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Map showing selected United States city sites (34) and new 1-secondgroun mo ons au s s own w re nes


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-

Average values of current (ASCE 7-10) and prior (ASCE 7-05)ground motions for each region and all 34 selected sites in the


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-

SRegion

7-98 (7-02) 7-05 7-10

Southern CA 0.63 0.65 0.70

or ern 0.64 0.61 0.65

Pacific NW 0.46 0.44 0.49

Intermountain 0.41 0.39 0.34CEUS 0.16 0.14 0.14

All regions 0.39 0.38 0.40

Average values of current (ASCE 7-10) and prior (ASCE 7-05)ground motions for each region and all 34 selected sites in the


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ASCE/SEI 7-05 ASCE/SEI 7-10

DevelopersBSSC/FEMA Project 97

USGS NHMP (2002)

BSSC/FEMA Project 07

USGS NHMP (2008)Name MCE GMs MCERGMs

Probabilistic GMs

(objective)

Uniform hazard

(2%-in-50 yr Pr. GM Exc.)

Risk targeted

(1%-in-50yr Pr. Collapse)

Deterministic * 84%-ileGMs

.(approx. 1.8*median)

GM parameter Geometric mean, Sa Maximum direction, Sa

Java ground motion Seismic design maps web

parameter calculator application

Average SDS 0.73g 0.72g

Average SD1 0.38g 0.40g


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00 asce c whittaker 2

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