ASCE 7ASCE 7 10 Seismic Provisions10 Seismic ProvisionsASCE 7ASCE 7--10 Seismic Provisions10 Seismic Provisions

TimeTime--History Scaling for 3History Scaling for 3--D Dynamic AnalysisD Dynamic AnalysisLiquefaction ProvisionsLiquefaction Provisions

SiteSite--Response Analysis for LiquefactionResponse Analysis for Liquefaction

Model CalibrationModel CalibrationArray Data & ResultsArray Data & Results

C. B. CrouseC. B. CrouseURS CorporationURS CorporationURS CorporationURS Corporation

2008 USGS S2008 USGS S and Sand S Maps in ASCE 7Maps in ASCE 7 10 will be10 will be2008 USGS S2008 USGS SSS and Sand SII Maps in ASCE 7Maps in ASCE 7--10 will be10 will be

H2

n( g

)

Max Sa

a H1

t 1 d f

Acc

.in

Hdi

r ect

ion

a H2

t 1 d.o.f.

H1Acc. in H1direction (g)

at

H1

H2

2002 USGS S and S Ground Motion Maps in ASCE 7 05 are2002 USGS SS and SI Ground Motion Maps in ASCE 7-05 are

S * S ( t i )Sa1 * Sa2 (geometric mean)

Geometric Mean = SaGeometric Mean = Sa * Sa* SaGeometric Mean = SaGeometric Mean = Sa11 * Sa* Sa22

AccelerogramHorizontal Components

Response Spectra

a H1

t

H1Sa

Sa1

a H2

t

H2SaTi

T

at Sa2

TT

Ti

Geomean Sa vs Max SaGeomean Sa vs Max SaGeomean Sa vs Max SaGeomean Sa vs Max Sa

Bedrock Response Spectra

x 1.1

Based on:

Sa x 1.3 Max Sa

Geomean Sa

1.0T (sec)

TimeTime--History Scaling for H1 and H2 components History Scaling for H1 and H2 components ––y g py g p3D Analysis3D Analysis

ASCE 7-05 ASCE 7-10

ave. SRSS Sa of scaleda(t) records

ave. SRSS Sa of scaleda(t) records - R 5 km

orave. Sa of scaled FN comp.of a(t) records R < 5 km

>

Sa1.3 x Target Sa

Target

of a(t) records - R < 5 km

1.5 TPeriod (sec)

Target(geomean Sa)

0.2 T 1.5 TPeriod (sec)

Target(max Sa)

0.2 T( )

GroundGround Motion RecordsMotion RecordsGroundGround--Motion RecordsMotion Records

Design Ground Motion Libraryg y

Transform FN & FP a(t) into X & Y a(t)Transform FN & FP a(t) into X & Y a(t)Transform FN & FP a(t) into X & Y a(t)Transform FN & FP a(t) into X & Y a(t)

Fault

Liquefaction AssessmentLiquefaction AssessmentLiquefaction AssessmentLiquefaction Assessment

ASCE StandardASCE Standard77--0505

GroundGround--Motion ParameterMotion ParameterSSSS / 2.5/ 2.5

77--1010 PGA (geomean)PGA (geomean)ffforfor

Site ClassSite Class

MCE Geometric Mean PGA, %g, Site Class BMCE Geometric Mean PGA, %g, Site Class B

Site Coefficients FSite Coefficients F

Mapped Ma im m ConsideredSite

Site Coefficients FSite Coefficients FPGAPGA

Mapped Maximum Considered Geometric Mean Peak

Ground Acceleration, PGA

SiteClass

A 0 8 0 8 0 8 0 8 0 8

PGA 0.1

< PGA =0.2

PGA =0.3

PGA =0.4

PGA >0.5

ABC

0.81.01.2

0.81.01.2

0.81.01.1

0.81.01.0

0.81.01.0C

DE

1.21.62.5

1.21.41.7

1.11.21.2

1.01.10.9

1.01.00.9

F See Section 11.4.7Note: Use straight-line interpolation for intermediate values of PGA.

Site Response AnalysisSite Response Analysis Liquefiable SoilsLiquefiable SoilsSite Response Analysis Site Response Analysis –– Liquefiable SoilsLiquefiable Soils

1964 M7.5 Niigata, Japan, Earthquake Damage from 1964 M7.5 Niigata, Japan, Earthquake Damage from g , p , q gg , p , q gLiquefactionLiquefaction

1964 M 7.51964 M 7.5NiigataNiigata

Onset

Niigata Niigata EarthquakeEarthquake

Liquefaction Onset~ 8-10 sec afterstart of strongstart of strongshaking

2003 M 8 3 Tokachi2003 M 8 3 Tokachi oki Japan Earthquakeoki Japan Earthquake2003 M 8.3 Tokachi2003 M 8.3 Tokachi--oki, Japan, Earthquakeoki, Japan, Earthquake

HKD 086

FaultRupture

2003 M 8.3 Tokachi2003 M 8.3 Tokachi--oki Earthquakeoki EarthquakeHKD 086 NS CompHKD 086 NS CompHKD 086 NS Comp.HKD 086 NS Comp.

0.4

0.6

liquefaction onset –upper 10m fine sand

-0.2

0.0

0.2

a-g

-0.8

-0.6

-0.4

25 30 35 40 45 50 55 6025 30 35 40 45 50 55 60t - sec

2.5

3.0

3.5

2.9 g @ T = 0.36 sec

ξ = 5%

1.0

1.5

2.0

Sa-g

0.0

0.5

1.0

0 0.5 1 1.5 2 2.5 3 3.5 4T - sec

Acceleration Response to HKD 086 NS CompAcceleration Response to HKD 086 NS CompAcceleration Response to HKD 086 NS Comp.Acceleration Response to HKD 086 NS Comp.

3

4

2 9g

1

0

1

2

3

a-g

2.9g

-4

-3

-2

-1

25 30 35 40 45 50 55 60

-2.9g

T = 0.36st - sec

0.2

0.4

0.6ξ = 5%

-0.4

-0.2

0.0a-g

-0.8

-0.6

25 30 35 40 45 50 55 60t - sec

Soil PropertiesSoil Properties Liquefied LayerLiquefied LayerSoil Properties Soil Properties –– Liquefied LayerLiquefied Layer

or G (or Vs), d –or G (or Vs), d constants

GroundGround--Motion DataMotion DataSiteSite--Response CalibrationResponse Calibration

Port Island, Japan. 1995 Kobe M 6.9Port Island, Japan. 1995 Kobe M 6.9Wildlife Array, CA. 1987 Superstition Hills M 6.6Wildlife Array, CA. 1987 Superstition Hills M 6.6

Port Island, JapanPort Island, Japan, p, pVertical Accelerometer ArrayVertical Accelerometer Array

-10

-20

-30

-40

(m)

-50

-60Dep

th

-70

-80

0 20 40 600 200 400SPT N values V (m/s)SRef: Elgamal et al. (1996)

Port Island Array EW RecordsPort Island Array EW Recordsyy1995 M 6.9 Kobe Earthquake1995 M 6.9 Kobe Earthquake

Ref.: Davis & Berrill (1998)

Port Island Port Island –– 1995 Kobe Earthquake1995 Kobe EarthquakeqqVVSS versus Timeversus Time

Depthp

0 mm

)

16 m

spla

cem

ent (

m

32 m

Dis

Ref.: Davis & Berrill (1998)

Port Island Port Island –– 1995 Kobe Earthquake1995 Kobe EarthquakeqqVVSS versus Timeversus Time

400

300

m/s

ec)

100

200

V(m

S

0

100

0 10 20 30 400 10 20 30 40Time (sec)

Ref: Elgamal et al. (1996)

Location Map of Wildlife ArrayLocation Map of Wildlife ArrayLocation Map of Wildlife ArrayLocation Map of Wildlife Array

Ref.: Holzer & Youd (2007)

Wildlife Array InstrumentationWildlife Array InstrumentationWildlife Array InstrumentationWildlife Array Instrumentation

99

V (m/sec)S

116116-141

168

Ref: Bennett et al. (1984)Holzer & Youd (2007)

Wildlife NS AccelerogramsWildlife NS Accelerogramsgg1987 M 6.6 Superstition Hills EQ1987 M 6.6 Superstition Hills EQ

200

Surface 0

m/s

ec/s

ec

-200200

cm

Downhole 0

cele

ratio

n

-200

Acc

10 20 30 40 50 60 70 80 90Ti ( )

Ref.: Zeghal & Elgamal (1994)

Time (sec)

Wildlife Wildlife –– 1987 Superstition Hills EQ1987 Superstition Hills EQppVVSS versus Timeversus Time

(m/s

ec)

V

S

Ref.: Zeghal & Elgamal (1994)

Estimation of Material Damping Ratio (ξ) Estimation of Material Damping Ratio (ξ) p g (ξ)p g (ξ)Liquefied SoilLiquefied Soil

a(t) recordsfrom

Port Is. & Wildlife

ξ ~ 20%ξ

Wildlife SiteWildlife SiteSurface Accelerograph StationSurface Accelerograph Station

USGS El Centro Station 6USGS El Centro Station 6USGS El Centro Station 6USGS El Centro Station 6

0

Y

1.22 m

0.51 m

2

4

6

-m

1.14 m

8

10

12

Dept

h-

X

Z recorded a(t)free field14

0 100 200 300 400

V – m/secS

X

0.100.15

( )ee e da (t)

Experimental Transfer Function (low strain)Experimental Transfer Function (low strain)Experimental Transfer Function (low strain)Experimental Transfer Function (low strain)

2

Station 6

1Recorded

Free Field

010 20 30 40 50 60

f - HzRef. Crouse & Hushmand (1989)

Approximate Transfer Function (liquefaction)Approximate Transfer Function (liquefaction)pp ( q )pp ( q )VVSS

liqliq = V= VSSlow strainlow strain, Pad Thickness = 6”, Pad Thickness = 6”1

10

2

Station 6

1Recorded

Free Field

01 2 3 4 5 6

f - Hz

Approximate Transfer Function (liquefaction)Approximate Transfer Function (liquefaction)pp ( q )pp ( q )VVSS

liqliq = V= VSSlow strainlow strain, Pad Thickness = 12”, Pad Thickness = 12”1

10

2

Station 6

1Recorded

1Free Field

0 1 2 3 4 5 6f - Hz

Site Response Analysis Site Response Analysis p yp y(liquefaction & non(liquefaction & non--liquefaction cases)liquefaction cases)

Saoa

T Ratio, Sao Sa

i

i1

non-liquef.

Sai

T

Tliquef.

T

SummarySummarySummarySummary

New Seismic Provisions in ASCE 7New Seismic Provisions in ASCE 7--1010

1. 3-D Dynamic Analysis – Accelerogram Scaling

Scale SRSS to Target Sa (not 1.3 X Target Sa)

2. Ground-Motion Parameter for Liquefaction

Geomean PGA (not S / 2 5 or S / 2 5)Geomean PGA (not SDS / 2.5 or SS / 2.5)

Summary (con’t )Summary (con’t )Summary (con’t.)Summary (con’t.)

Liquefied Soil Parameters for Equivalent Linear Liquefied Soil Parameters for Equivalent Linear SiteSite--Response AnalysisResponse Analysis

Use Vertical Accelerometer Array Data

V = 15 30 m/sVS = 15 – 30 m/s

ξ ~ 20% w/o Port Island &Wildlife

soil-pad interaction