(& ASCE/SEI 7-16 - c.ymcdn.comc.ymcdn.com/sites/ · PDF file(& ASCE/SEI 7-16) 2016 ASCE...

EERI Seminar on Next Generation Attenuation Models

Updated MCER & MCEG Ground Motions in 2015 NEHRP Provisions

(& ASCE/SEI 7-16)

2016 ASCE Geotechnical & Structural Engineering Congress

Nicolas Luco Research Structural Engineer, USGS (Golden, CO)

BSSC PUC Design Mapping Issue Team (“IT-11”) (Bachman, Crouse, Harris, Hooper, Kircher, Caldwell)


ASCE/SEI 7-10

“Recent Changes to Peak Ground Accelerations in the ASCE/SEI 7 Standard,” N. Luco (USGS) February 15, 2016

2016 ASCE Geotechnical & Structural Engineering Congress: Course on “… 2015 NEHRP Provisions”


ASCE/SEI 7-10

“Recent Changes to Peak Ground Accelerations in the ASCE/SEI 7 Standard,” N. Luco (USGS) February 15, 2016

FIGURE 22-7 MAXIMUM CONSIDERED EARTHQUAKE GEOMETRIC MEAN (MCEG) PGA …, SITE CLASS B …



Outline of this presentation

“Updated MCER and MCEG Ground Motions in 2015 NEHRP Provisions,” N. Luco (USGS) et al February 14, 2016


• Updates to MCER (& MCEG) maps for conterminous US for 2015 NEHRP Provisions (and ASCE 7-16)

• Comparisons with values from ASCE 7-10

• Comparisons with previous editions of ASCE 7-05 and ASCE 7-02/7-98

• Impacts on Seismic Design Categories

• Updates to MCER (& MCEG) maps for Guam, the Northern Mariana Islands, and American Samoa

• Summary


2) Fragility curve β = 0.8 β = 0.6, for consistency with the site-specific ground motion chapter (Ch. 21) of ASCE 7-10

Reasons for Updated Design Maps

1) 2014 USGS National Seismic Hazard Model (including NGA-West2, UCERF3, CEUS-SSC)



10-1

100

101

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Spectral Acceleration (1.0 sec), a [g]

P [

Col

laps

e | S

A =

a ]

β = 0.8β = 0.6


USGS Hazard Model Updates

“Proposed seismic maps for the conterminous United States,” N. Luco, USGS et al September 17, 2015

American Society of Civil Engineers 7-16 Standard (ASCE 7-16) Main Committee Webinar

•

• Others listed in Chapter 22 Commentary and explained in December 2015 Special Issue of Earthquake Spectra journal

Project Name Lead(s) Duration Sponsors Central & Eastern US Seismic Source Characterization for Nuclear Facilities (CEUS-SSC)

Consultants 2008-2011

US DOE, EPRI, US NRC

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)

USGS, CGS, SCEC (WGCEP)

2010-2013

CEA

Next Generation Attenuation Relations for Western US, Version 2 (NGA-West2)

PEER 2010-2013

CEA, Caltrans, PG&E


Fragility β=0.8 β=0.6 Update



• For 2009 NEHRP Provisions MCER ground motions & site-specific ground motion chapter (Ch. 21), the BSSC Seismic Design Procedures Reassessment Group settled on β = 0.8

• For 2010 ASCE 7 Standard Ch. 21 (but not MCER maps), the Seismic Subcommittee (SSC) Ad-Hoc Ground Motion Committee updated to β = 0.6, based on …


Changes at 34 High-Risk Locations



Name Latitude Longitude Name Population

Los Angeles 34.05 -118.25Century City 34.05 -118.40Northridge 34.20 -118.55Long Beach 33.80 -118.20Irvine 33.65 -117.80 Orange 3,002,048Riverside 33.95 -117.40 Riverside 2,026,803San Bernardino 34.10 -117.30 San Bernardino 1,999,332San Luis Obispo 35.30 -120.65 San Luis Obispo 257,005San Diego 32.70 -117.15 San Diego 2,941,454Santa Barbara 34.45 -119.70 Santa Barbara 400,335Ventura 34.30 -119.30 Ventura 799,720

22,349,098 Population - 8 Counties 21,374,778Oakland 37.80 -122.25 Alameda 1,502,759Concord 37.95 -122.00 Contra Costa 955,810Monterey 36.60 -121.90 Monterey 421,333Sacramento 38.60 -121.50 Sacramento 1,233,449San Francisco 37.75 -122.40 San Francisco 776,733San Mateo 37.55 -122.30 San Mateo 741,444San Jose 37.35 -121.90 Santa Clara 1,802,328Santa Cruz 36.95 -122.05 Santa Cruz 275,359Vallejo 38.10 -122.25 Solano 423,473Santa Rosa 38.45 -122.70 Sonoma 489,290

14,108,451 Population - 10 Counties 8,621,978

Total Population - S. California

RegionCity and Location of Site County or Metropolitan Statistical Area

9,948,081Los AngelesN

orth

ern

Cal

iforn

iaSo

uthe

rn C

alifo

rnia

Total Population - N. California …


Changes at 34 High-Risk Locations



Name Latitude Longitude Name Population

RegionCity and Location of Site County or Metropolitan Statistical Area

Seattle 47.60 -122.30 King WA 1,826,732Tacoma 47.25 -122.45 Pierce WA 766,878Everett 48.00 -122.20 Snohomish WA 669,887Portland 45.50 -122.65 Portland Metro OR (3) 1,523,690

10,096,556 Population - 6 Counties 4,787,187Salt Lake City 40.75 -111.90 Salt Lake UT 978,701Boise 43.60 -116.20 Ada/Canyon ID (2) 532,337Reno 39.55 -119.80 Washoe NV 396,428Las Vegas 36.20 -115.15 Clarke NV 1,777,539

6,512,057 Population - 5 Counties 3,685,005St. Louis 38.60 -90.20 St. Louis MSA (16) 2,786,728Memphis 35.15 -90.05 Memphis MSA (8) 1,269,108Charleston 32.80 -79.95 Charleston MSA (3) 603,178Chicago 41.85 -87.65 Chicago MSA (7) 9,505,748New York 40.75 -74.00 New York MSA (23) 18,747,320

48,340,918 Population - 57 Counties 32,912,082

Total Population - ID/UT/NV

Total Population - MO/TN/SC/IL/NY

CEU

SO

ther

WU

SPa

cific

N

orth

wes

t

Total Population - OR and WA

…



34 City Locations from 2009 Provisions



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 340.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

City Location #

Prop

osed

÷ A

SCE

7-1

0 G

roun

d M

otio

n

Southern California Northern California PacNW IMW CEUS

SS (MCER)

S1 (MCER)

PGA (MCEG)

Changes in MCER & MCEG Values



San

ta B

arba

ra

Las

Vega

s

Irvin

e

San

Die

go

Cha

rlest

on


Underlying Components of SS and S1



• As laid out in the 2009 NEHRP Provisions (& Ch. 21) … …

SS = min( CRS SSUH, SSD )

S1 = min( CR1 S1UH, S1D )


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 340.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

City Location #

Prop

osed

÷ A

SCE

7-1

0 G

roun

d M

otio

n


SSUHS1UH"PGAUH"

Changes in USGS Uniform-Hazard Values



Las

Vega

s

San

ta B

arba

ra

San

Die

go


Changes at Las Vegas Location



• In ASCE 7-10 maps, rate of earthquakes on Eglington fault is ~1/14,000yrs.

• Based on recent publications (references in dePolo et al, 2013), …

• Nevada Bureau of Mines & Geology recommended, in effect, a rate of ~1/600yrs.

• Through additional communication with USGS, all agreed on ~1/2,100yrs.


Changes at Santa Barbara Location



• ASCE 7-10 maps are based on UCERF2 in California.

• UCERF3 includes more multi-fault earthquakes (like 2011 M7.2 El Mayor-Cucapah), in part to remove UCERF2 over-prediction of M6.5-7 earthquakes.

• This, in effect, lowers rate of earthquakes that dominate hazard in Santa Barbara.

• ASCE 7-10 maps are based on NGA-West1 for Western U.S. crustal earthquakes.

• NGA-West2 includes recent data from 2009 M6.3 L’Aquila, 2008 M7.9 Wenchuan & 5 other earthquakes on dipping faults, as well as 130,000 ground motion simulations.

• The effect was to decrease best estimates of ground motions over reverse faults near Santa Barbara.


Commentary on Additional Changes




1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 340.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

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1.8

City Location #

Prop

osed

÷ A

SCE

7-1

0 R

isk C

oeffi

cien

t


CRS

CR1

Changes in Risk Coefficients




Changes in Deterministic Values



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 340.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

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City Location #

Prop

osed

÷ A

SCE

7-1

0 G

roun

d M

otio

n


SSDS1D"PGAD"


• UCERF3 includes multi-fault ruptures (M8+), in part to remove UCERF2 overprediction of M6.5-7 earthquakes.

Deterministic Earthquakes




• UCERF3 also includes low-activity-rate faults, e.g., …





From ASCE 7-10 site-specific ground motion chapter (Ch. 21):




• For 2015 NEHRP Provisions, characteristic earthquakes from UCERF2 (& ASCE 7-10) have been updated and used in lieu of UCERF3 multi-fault ruptures, and …

• “Active” faults have been defined as those with Holocene (last ~12K years) displacement/slip, or with slip rate > 0.1 mm/year. All other faults have been excluded.


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 340.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

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City Location #

Gro

und

Mot

ion

Rat

io


ASCE 7-10 ÷ ASCE 7-05 , SS

ASCE 7-10 ÷ ASCE 7-05 , S1

ASCE 7-05 ÷ ASCE 7-98 , SS

ASCE 7-05 ÷ ASCE 7-98 , S1

Previous Changes in MCE(R) Values



Precision vs. Uncertainty

ASCE 7 Edition

2000 2005 2010 2015

Spe

ctra

l Res

pons

e A

ccel

erat

ion,

g

0.5

1

1.5

2

2.5

Santa Barbara

SS

S1

ASCE 7 Edition

2000 2005 2010 2015S

pect

ral R

espo

nse

Acc

eler

atio

n,

g

0.5

1

1.5

2

2.5

Ventura

SS

S1

Precision vs. Uncertainty


Changes in Seismic Design Categories



Default Site Class

Seismic DesignCategory (SDC)

A

B

C

D

E


SDC changes

B → C

C → B




Default Site Class





Default Site Class

SDC changes

D → E

E → D


Deeper Explanations of Changes




Guam & Tutuila in ASCE 7-10

“New Design Ground Motions in 2015 NEHRP Provisions …,” N. Luco (USGS) & IT-11 November 13, 2015

2015 COSMOS Technical Session: Current Ground-Motion Design Value Maps – Issues & Proposed Solutions


USGS Hazard Model for Guam




USGS Hazard Model for Tutuila




MCER Maps for 2015 Provisions



13°

14°

15°

16°

13°

14°

15°

16°

Northern Mariana Islands

Guam

200

150

125

100908070

6070 80

100

125

150

90

200

200.2

250.6

288.6

243.9

13°

14°

15°

16°

13°

14°

15°

16°

Northern Mariana Islands

Guam 2530

4050

60

72.3

1.0 Second Spectral Response Acceleration(5% of Critical Damping)

0.2 Second Spectral Response Acceleration(5% of Critical Damping)

100 0 100 200 Miles

100 0 100 200 Kilometers

. SS = 287%g

. SS = 176%g

. S1 = 72%g

. S1 = 44%g


MCER Maps for 2015 Provisions



OfuOlosega

Ta'u

Tutuila

Aunu'u

SwainsIsland

RoseAtoll

AmericanSamoa

172° 171° 170° 169° 168°

15°

14°

13°

12°

11°

15°

14°

13°

12°

11°

125

10090

8070

6050

40

35

30

60

50

40

2520

15

10

5

0.2 Second Spectral Response Acceleration (5% of Critical Damping)

OfuOlosega

Ta'u

Tutuila

Aunu'u

SwainsIsland

RoseAtoll

AmericanSamoa

172° 171° 170° 169° 168°

15°

14°

13°

12°

11°

5°

4°

3°

2°

1°

50

40

3025

20

15

10

8

6

415

2

15

1.0 Second Spectral Response Acceleration (5% of Critical Damping)

. SS = 40%g . S1 = 15%g


2015 Provisions Ch. 22 Commentary



… In comparing the MCER ground motion maps derived from these USGS hazard models to the geographically-constant values stipulated for Guam and American Samoa (Tutuila) in the 2010 and previous editions of ASCE/SEI 7, it is important to bear in mind that the latter were not computed via seismic hazard modeling. According to the commentary of the 1997 Provisions, the geographically-constant values were merely conversions, via rough approximations, from values on the 1994 Provisions maps that had been in use for nearly 20 years. As such, they did not take into account the 1993 Guam earthquake that was the largest ever recorded in the region and caused considerable damage, the 2009 earthquake near American Samoa that caused a tsunami, nor the 2008 “Next Generation Attenuation (NGA)” and another 2006 empirical ground motion prediction equation that have now been used for both Guam/NMI and American Samoa. …


Summary



• Conterminous US updates include (i) 2014 USGS NSHM, (ii) β=0.6, and (iii) definition of “active faults” for deterministic ground motions.

• Amongst 34 high-risk locations, 9/10-ths of design map changes are within +/-20%, 2/3-rds are within +/-10%.

• Most of the >20% changes are due to significant USGS hazard model updates.

• Seismic Design Categories change in relatively small areas, mostly at relatively low-risk locations.

• Uncertainty in design ground motions desired for perspective.


Updated Design Maps Web Tool



http://earthquake.usgs.gov/designmaps/beta/us/


Risk-Targeted Ground Motion Calculator




Bonus Slides …







Site Class B

SDC changes

B → C

C → B

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