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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
DHS/FEMA ATC-58 ProjectDHS/FEMA ATC-58 Project
Selection and Scaling of GroundSelection and Scaling of Ground
MotionsMotions
Yin-Nan Huang
University at Buffalo
Andrew Whittaker, S.E.,
University at Buffalo
ATC-58 SPP Team Lead
Ron Hamburger, S.E.
Simpson, Gumpertz & Heger, Inc
ATC-58 Project Lead
2006 COSMOS Annual Meeting
Berkeley, California,
November 17, 2006
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Discussion itemsDiscussion items
ATC-58 project
Procedures for scaling ground motions! Method 1: geometric mean
!Method 2: spectrum-matching
! Method 3: Sa at T1! Method 4: amplitude scaling to spectral stripes
Performance assessment!
Intensity-based assessments! Scenario-based assessments
! Time-based assessments
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
ATC-58 ProjectATC-58 Project
Next generation tools and
guidance for performance based
seismic assessment and design
! FEMA 273/356 (ATC-33 project)
! PEER research program
! Phase I: assessment tools (2009)
! Phase II: design tools (2014)
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
ATC-58 ProjectATC-58 Project
Assessment options! Intensity: response spectrum
"Median response
! Scenario: [M, r] pair"Median response and dispersion
! Time-based: seismic hazard curve"Median responses and dispersions
Seismic hazard analysis
! USGS seismic hazard maps! PSHA
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Scaling procedures: method 1Scaling procedures: method 1
Amplitude scale a pair of motions to minimize thesum of the residuals between the target spectrumand the geometric-mean spectrum
Preserves both correlation between components of a
pair and irregular shape of spectra
0 1 2 3 4Period (sec)
0
0.5
1
1.5
2
2.5
Spectra
lacceleration
(g
EQ1
EQ2
Geometric mean
Target spectrum
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
50 pairs of amplitude-scaled NF (25) and FF motions
Spectral shapes for the median and target spectra
Dispersion in spectral demand retained
Benchmark dataset (Bin 1)
Scaling procedures: method 1Scaling procedures: method 1
0 1 2 3 4Period (sec)
0
1
2
3
4
Spectralacceleration
(g
0 1 2 3 4Period (sec)
0
1
2
3
4
Spectralacceleration
(g
Median
16thand 84th
Target spectrum
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Scaling procedures: method 2Scaling procedures: method 2
Spectrum-matching using RSPmatch
Bin 2 motions are spectrum-matched Bin 1 motions
Target spectra: median NF and FF spectra of Bin 1
0 1 2 3 4Period (sec)
0
0.5
1
1.5
2
2.5
Spectralacceleration
(
0 1 2 3 4Period (sec)
0
0.5
1
1.5
2
2.5
Spectralacceleration
(
Median, 16thand 84th
Bin 1
Bin 2
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Scaling procedures: method 3Scaling procedures: method 3
Amplitude-scale individual ground motion records to atarget spectral acceleration at T1(Shome, Cornell, et al.)
0 0.5 1 1.5 2Period (sec)
0
1
2
3
4
Spe
ctralacceleration
(
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Scaling procedures: method 4Scaling procedures: method 4
Sample spectral striping
! Computation at 1 second
! 5 stripes
!"=0.3g and #=0.4
0 0.2 0.4 0.6 0.8 1Spectral acceleration (g)
0
1
2
3
4
5
Probabilitydensityfunction
!=0.3g; "=0.4
0 0.2 0.4 0.6 0.8 1Spectral acceleration (g)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Cumulative
distributionfunction
!=0.3g; "=0.4
a.
b.
x1 x2 x3 x4 x5
0 0.5 1 1.5 2Period (sec)
0
0.2
0.4
0.6
0.8
1
Spectral
acceleration
(g)
c.
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Scaling procedures: method 4Scaling procedures: method 4
Generate 11 spectral stripes using "and #; Bin 1 FF
Amplitude scale one ground motion, randomlyselected from Bin 1 FF, to one of the spectral stripesat the first mode period; repeat 11 times with
randomly selected motions
0 1 2 3 4Period (sec)
0
1
2
3
Spectra
lacceleration
(g) 11 spectral stripes
using !and "in Bin 1 motions
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Evaluation of method 2Evaluation of method 2
Nonlinear response analysis of bilinear oscillators
! Yield strength: infinity, 0.4W, 0.2W, 0.1W and 0.06W
! Underestimates median (nonlinear); dispersion is lost
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.2
0.4
0.6
Peakdisplacement,Sd(
a. 84th, 50thand 16th
pers. of Sd, elasticb. 84th, 50thand 16th
pers. of Sd, Fy=20%Wc. 84th, 50thand 16th
pers. of Sd, Fy=6%W
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.2
0.4
0.6
2 2.4 2.8 3.2 3.6 4Period2(sec)
0
0.2
0.4
0.6LL
L
Bin 2
yield displacement
Bin 1
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Evaluation of method 3Evaluation of method 3
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.2
0.4
0.6
Pe
akdisplacement,Sd(
a. 84th, 50thand 16th
pers. of Sd, elasticb. 84th, 50thand 16th
pers. of Sd, Fy=20%Wc. 84th, 50thand 16th
pers. of Sd, Fy=6%W
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.2
0.4
0.6
2 2.4 2.8 3.2 3.6 4Period2(sec)
0
0.2
0.4
0.6L
L
L
Bin 3
yield displacement
Bin 1
Nonlinear response analysis of bilinear oscillators
! First mode period scaled motions across range of periods
! Unbiased estimate of median
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Evaluation of method 4Evaluation of method 4
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.2
0.4
0.6
!
(m)
a. !, elastic b. !, Fy=20%W c. !, Fy=6%W
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.2
0.4
0.6
2 2.4 2.8 3.2 3.6 4Period2(sec)
0
0.2
0.4
0.65
Median of Bin 1
Distribution formedian estimateof Bin 4(16,50,84)
Nonlinear response analysis of bilinear oscillators
! Yield strength: infinity, 0.4W, 0.2W, 0.1W and 0.06W
! 10,000 combinations of 11 seed motions from Bin 1
! Unbiased estimate of median
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
c. !, Fy=6%Wb. !, Fy=20%Wa. !, elastic
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.4
0.8
1.2
!
0 0.4 0.8 1.2 1.6 2Period1(sec)
0
0.4
0.8
1.2
2 2.4 2.8 3.2 3.6 4Period2(sec)
0
0.4
0.8
1.25
Nonlinear response analysis of bilinear oscillators
! Yield strength: infinity, 0.4W, 0.2W, 0.1W and 0.06W
! 10,000 combinations of 11 seed motions from Bin 1
! Overestimates dispersion in displacement response
!of Bin 1Distribution for
estimate of !for Bin 4(16,50,84)
Evaluation of method 4Evaluation of method 4
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Method 1: geometric mean! Pros: retains irregular spectral shape and
correlation between components; no need to
compute T1easy to implement;! Cons: finding a set of ground motions with a
median (or mean) spectrum that matches thetarget spectrum; treatment of dispersion
Method 2: spectrum matching
! Pros: no need to compute T1; easy to implement! Cons: underestimates median displacement
demand in highly nonlinear systems; greatlyreduces dispersion
Summary-1Summary-1
0 1 2 3 4
Period (sec)
0
0.5
1
1.5
2
2.5
Spectralacceleration
(
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Method 3: Sa at T1! Pros: unbiased estimate of median demand; easy
to implement
! Cons: dispersion is lost for near-elastic systems;need to know T1
Method 4: Spectral-stripes
! Pros: unbiased median demand; conservatively
estimates dispersion! Cons: minor level of complexity; need to know T1
0 1 2 3 4
Period (sec)
0
0.5
1
1.5
2
2.5
Spectralacceleration
(
Summary-2Summary-2
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Intensity-based assessmentIntensity-based assessment
Calculate loss given a response spectrum
Compute mediandisplacements and accelerationsonly; some dispersion retained
Hazard representation!
5% damped spectrum for horizontal shaking Scaling procedure! Amplitude scale a number (n) of recorded ground motions
(NF or FF) using Method 3: Sa at T1! Required number is a function of dispersion in the
displacement response given the scaling procedure,required accuracy of the estimate, and required confidencein the estimate
! For #=0.55, 75% confidence, 20% of median, 12 groundmotions required.
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Calculate a distribution of loss (median, fractiles)given an earthquake magnitude and distance
Compute the mediandisplacements andaccelerations and their dispersions
Hazard representation! Median spectral demand and dispersions in the demand
defined by a controlling [M, r] pair and an attenuationrelationship
Scaling procedure!
Generate 11 spectral curves based on median demands anddispersions
! Amplitude-scale 11 recorded ground motions, one per stripe(value of Sa) at T1
Scenario-based assessmentScenario-based assessment
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
Time-based assessmentTime-based assessment
Establish distribution of annualized loss
Compute the mediandisplacements andaccelerations and their dispersions at selectedannual frequencies of exceedance
Hazard representation! Seismic hazard curves
Scaling procedure! Determine mean spectral ordinates at the selected
frequencies of exceedance and T1! Amplitude scale 12 recorded ground motions to the target
spectral ordinates using Method 3
! Series of intensity-based assessments
! Method 4 scaling could be used to capture dispersion(epistemic uncertainty) at each annual frequency ofexceedance
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Issues yet to be addressedIssues yet to be addressed
Multi-mode scaling rules! Mid-rise and high-rise buildings
! Nonstructural components and systems
Scaling of small AFE (0.0004), near-fault motions
! ATC-63 project recommendations Rotated geometric mean and max/min shaking
! USGS seismic hazard maps and correction factors
! BSSC Project 07
Forward rupture directivity
! BSSC Project 07! FN and FP motions
Three-components sets of acceleration histories
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ATC-58: Development of Next-Generation Performance-Based Seismic Design Guidelines
AcknowledgmentsAcknowledgments
Robert Bachman
Craig Comartin
Allin Cornell
C.B. Crouse
Greg Deierlein
Robert Hanson
Stephen Harmesan Jon Heintz
John Hooper
Charles Kircher
E.V. Leyendecker
Nico Luco
Michael Mahoney
Andy Merovich
Jack Moehle Paul Somerville
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