1 Structural Responses – Preliminary Results and Observations PEER GMSM Program Workshop, Richmond...

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Structural Responses – Preliminary Structural Responses – Preliminary

Results and ObservationsResults and Observations

PEER GMSM Program Workshop, Richmond CA, October 29, 2007PEER GMSM Program Workshop, Richmond CA, October 29, 2007

Curt B. Haselton, PhD, PECurt B. Haselton, PhD, PE

Assistant ProfessorAssistant Professor

California State University, ChicoCalifornia State University, Chico

And other members of PEER GMSM Working GroupAnd other members of PEER GMSM Working Group

2

Our Purpose for the Next Two HoursOur Purpose for the Next Two Hours

The purpose of convening everyone to review the

preliminary results is:

To ensure that we correctly interpret the various methods.

To obtain feedback and insights from the group.

Our approach to interpreting the results

Our specific observations

Other things that we may need to think about or address

To begin the process of coming to a collective consensus.

The product of this study will be more useful to the ground

motion community if we can all establish a group

agreement on the results.

Note: Our dialogue will be ongoing, but this is our only

formal meeting before the preparation of the first PEER

report.

3

OutlineOutline

Introduction to the results figures and the

available results files

Brief overview of preliminary results (15

minute overview before starting detailed

discussion)

Detailed review of preliminary results and

observations (1.5 hours of review and group

discussion)

4

9980 9980 99809980 9981 99819981 9981 9982 99829982 9982 99839983 9983 99839984 9984 9984 99840

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sResults for Scenario: M7, Building: C, All GM Subsets

Point of Comparison

Counted MedianData Point

Introduction to Results FiguresIntroduction to Results Figures

The point of comparison (POC) is used to compare predictions to, as discussed previously.

The counted median response includes collapsed records (assuming they have a

very large MIDR).

A blue point at the top of the figure indicates collapsed record(s).

The number indicates the ratio of collapsed records to total records in the

set.

The method tags correspond to the numbers in the index Excel file.

There is one entry per ground motion set (typically four per method) Each blue data point is the response

from a single scaled ground motion record.

Numbers next to the “+” indicate that the sets are ranked, with #1 being better than

#4.

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To facilitate your detailed review, the following

files are available (on GMSM website, and

available USB drives):

Index of methods (provides method names/numbers)

Acceleration spectra for each method and ground

motion set

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Scenario: M7, Method: 10, Building: C, Record Set: 1, Obj.: 4

Median + 2 Prediction

Conditional MeanMedian of Rec. Set

Individual Records

Materials Available to Facilitate Detailed Materials Available to Facilitate Detailed ReviewReview

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motion set

Results for Buildings B, C, and D

PowerPoint overview of results (should not need

today)


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motion set

Results for Buildings B, C, and D

PowerPoint overview of results (should not need

today)

Excel file giving median predictions and comparison

to POC

Excel files giving detailed results for each method


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Overview of Structural Response ResultsOverview of Structural Response Results The overall study includes:

Four buildings (4-story frame, 12-story frame and wall, 20-story frame)

Four objectives (response conditioned on M, R and response conditioned on

M, R, and a +2σ Sa value)

We will focus on the results for:

Building C (20-story RC frame), with comparisons to Building D (12-story RC

wall) and Building A (4-story RC frame)

Objective 4 (predicting median MIDR for a +2σ motion).

Review results by classification:

Sa(T1) methods

Methods based on matching the uniform hazard spectrum (UHS)

Methods based on matching the conditional mean spectrum (CMS)

Methods using a proxy for spectral shape (e.g. ε)

Inelastic response based methods

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Overview: Sa(TOverview: Sa(T11) Scaling) Scaling

Median = 0.028

Ratio to POC: Bldg C

Median: 1.48

c.o.v.: 0.34

Minimum: 1.07

Maximum: 2.74

POC = 0.019

High

This is the coefficient of

variation of the median

predictions.

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Overview: Matching the UHSOverview: Matching the UHS

9980 9980 9980 9980 9981 9981 9981 9981 9982 9982 9982 9982 9983 9983 9983 99830

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Point of Comparison


Figure 1 of 3

Median = 0.024POC = 0.019

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9984 9984 9984 9984 9985 9985 9985 9985 9986 9986 9986 9986 9987 9987 9987 99870

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Figure 2 of 3

Median = 0.024POC = 0.019

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9988 9988 9988 9988 9989 9989 9975 9975 9975 9975 9976 9976 9976 99760

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Figure 3 of 3

Median = 0.024POC = 0.019


Median: 1.26

c.o.v.: 0.23

Minimum: 0.91

Maximum: 2.07

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Overview: Matching Conditional Mean Overview: Matching Conditional Mean SpectrumSpectrum

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Point of Comparison


Median = 0.019POC = 0.019


Median: 1.01

c.o.v.: 0.20

Minimum: 0.76

Maximum: 1.51

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Overview: Matching Conditional Mean Overview: Matching Conditional Mean SpectrumSpectrum

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Point of Comparison


Median = 0.019POC = 0.019


Median: 1.01

c.o.v.: 0.20

Minimum: 0.76

Maximum: 1.51


Median: 1.23

c.o.v.: 0.24

Minimum: 0.91

Maximum: 2.07

Matching UHS Matching CMS

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Matching UHS Matching CMS

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Overview: Proxy for Spectral Shape (e.g. Overview: Proxy for Spectral Shape (e.g. ε)ε)

57 57 57 57 58 58 58 58 30 31 31 31 31 20 20 20 200

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Point of Comparison


Median = 0.026POC = 0.019


Median: 1.37

c.o.v.: 0.46

Minimum: 0.79

Maximum: 3.55


Median: 1.15

c.o.v.: 0.30

Minimum: 0.79

Maximum: 1.88

With 57-58 removed All methodsCMS-matching


Median: 1.01

c.o.v.: 0.20

Minimum: 0.76

Maximum: 1.51

This 15% higher

prediction is also associate with a higher collapse rate.

CMS (and POC): 0/28

Proxy: 6/28

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Overview: Inelastic-Based MethodsOverview: Inelastic-Based Methods

A

A

A

a

Median = 0.022


Median: 1.14

c.o.v.: 0.19

Minimum: 0.76

Maximum: 1.58

Higher prediction again associated with higher collapse

rate.

CMS methods (and POC): 0/28

Inelastic methods: 3/28

POC = 0.019

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Overview of Structural Response ResultsOverview of Structural Response Results Results summary by method classification for Building C (median MIDR/POC):

Sa(T1) and UHS methods results in highly variable predictions which tend to be

larger than the POC.

Methods that match the CMS agree well with the POC.

CMS Proxy methods and Inelastic methods:

On average, results in response 15% higher than the POC.

This seems to also come with a higher collapse rate.

**These observations are an average or all methods in the class; some of the

individual methods have predictions nearly the same as the POC.

Sa(T1) UHS CMS *Proxy (i.e. ε) Inelastic

Median: 1.48 1.26 1.01 1.15 1.14

c.o.v.: 0.34 0.23 0.20 0.30 0.19

Minimum: 1.07 0.91 0.76 0.79 0.76

Maximum: 2.74 2.07 1.51 1.88 1.58

* With methods 57 and 58 removed.

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Overview of Structural Response ResultsOverview of Structural Response Results Comparison of results for Buildings A and D

Sa(T1) methods: Tend to over-predict response, predictions depend

on spectra shape and contributions of inelastic and higher-mode

responses.

Matching CMS: Predictions close to POC in all cases.

Proxy methods: Consistent at 10% above the POC.

Inelastic methods: 15% above the POC for frame buildings (C and A),

and right at POC for shear wall (Building D).

Median(MIDR/POC)Building T1

(sec)Sa(T1) UHS CMS

*Proxy (i.e. ε)

Inelastic

Building C (20-story RC frame) 2.63 1.48 1.26 1.01 1.15 1.14

Building A (4-story RC frame) 1.00 1.48 -- 1.05 1.05 1.17

Building D (12-story RC wall) 1.20 1.17 -- 0.94 1.09 1.00

* With methods 57 and 58 removed. Averages: 1.38 1.26 1.00 1.10 1.10

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OutlineOutline

Introduction to the results figures and the

available results files

Brief overview of preliminary results (15

minute overview before starting detailed

discussion)

Detailed review of preliminary results and

observations (1.5 hours of review and

group discussion)

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Detailed Review: Sa(TDetailed Review: Sa(T11) Scaling) Scaling

Overall Median = 0.028


Median: 1.48

c.o.v.: 0.34

Minimum: 1.07

Maximum: 2.74

POC = 0.019

Sa(T1) scaling (#4, 53)

Median = 0.037

Median = 0.022

ATC-58 30% draft Method (#67)

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Detailed Review: Sa(TDetailed Review: Sa(T11) Scaling (#4, 53)) Scaling (#4, 53)

Median = 0.037

POC = 0.019

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.94

Sa(T1) scaling (#4, 53)

Bin: [0 < R < 20km, 6.75 < M < 7.25]

Records in bin tend to have an average far-field spectral shape (higher

frequency content at shorter periods).

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]Scenario: M7, Method: 4, Building: C, Record Set: Combined, Obj.: 3,4



Individual Records

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.94

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Scenario: M7, Method: 4, Building: C, Record Set: Combined, Obj.: 3,4



Individual Records

Possible higher modes

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]Scenario: M7, Method: 4, Building: D, Record Set: Combined, Obj.: 3,4



Individual Records

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.94

- Building D (T1 = 1.2s): 1.13

Spectrum lowered due to scaling at 1.2s

rather than 2.63s.

Spectrum matches UHS at T1, but overall spectrum is 40-45%

lower.

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Observations/Comments:

Building C response is over-predicted 70% more than Building D,

and Building A over-prediction is 13% higher than D.

Comparing C (20-story frame; T1 = 2.63s) and D (12-story wall ; T1

= 1.2s):

Scaling period and spectral shape lead to a 40-45% difference in

the overall position of the spectrum.

For Building C, the spectrum falls off a bit more slowly at T > T1,

causing higher inelastic response.

Higher mode effects may also increase Building C response.

Comparing D and A:

Similar fundamental periods, but Building D has less structural

damage, so period elongation is less drastic.

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.94

- Building D (T1 = 1.2s): 1.13

- Building A (T1 = 1.0s): 1.28

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Detailed Review: Sa(TDetailed Review: Sa(T11) Scaling (#67)) Scaling (#67)

Median = 0.022

POC = 0.019

ATC-58 30% draft Method (#67)

[0 < R < 15km, M > 6.5]

Spectral shape differs from the previous methods – pulsy motions with more spectral content from

0.5-3.5 sec

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.17

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]Scenario: M7, Method: 67, Building: C, Record Set: Combined, Obj.: 4



Individual Records

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.17

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]Scenario: M7, Method: 67, Building: D, Record Set: Combined, Obj.: 4



Individual Records

Median MIDR / POC:

- Building C (T1 = 2.63s): 1.17

- Building D (T1 = 1.2s): 1.39

- Building A: (T1 = 1.0s): 1.48

Spectral shape is nearly the same as the UHS (for 0.5-3.5s).

Therefore spectral values are nearly unchanged when scaled to either Sa(1.2s) or Sa(2.63s).

However, spectral values at T > T1 are much greater for T1 =

1.0-1.2s.

Building A has higher response than D due to higher levels of

damage.

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Summary for Sa(T1):

MIDR/POC ranges from 1.11 to 1.94 for the various

methods and Buildings.

With Sa(T1) scaling, we scale all of the spectra to the

UHS at a given period. This causes predictions to be

highly variable and depend on:

The spectral shape of the record bin, as compared to the

UHS.

The period used for scaling.

These items affect the shape of the spectrum away

from T1, which affect inelastic response.

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A Detailed Look at Results of A Detailed Look at Results of

Building Code-Based Record Building Code-Based Record

SelectionSelection


Jack W. Baker, PhDJack W. Baker, PhD


Stanford University Stanford University


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IBC (ASCE 7-05) building code IBC (ASCE 7-05) building code requirementsrequirements

From ASCE 7-05, section 16.1.3.1:

“Each ground motion shall consist of a horizontal acceleration history, selected from an actual recorded event”

“obtained from records of events having magnitudes, fault distance, and source mechanisms that are consistent with those that control the maximum considered earthquake.”

“The ground motions shall be scaled such that the average value of the 5 percent damped response spectra for the suite of motions is not less than the design response spectrum for the site for periods ranging from 0.2T to 1.5T “

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Number of ground motionsNumber of ground motions

From ASCE 7-05, section 16.1.4:

“If at least seven ground motions are analyzed, the design member forces … and the design story drift … is permitted to be taken respectively as the average of the … values determined from the analyses”

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Site-specific design spectrumSite-specific design spectrumFrom ASCE 7-05, section 21.2.1:

“The probabilistic MCE spectral response accelerations shall be taken as the spectral response accelerations represented by a 5 percent damped acceleration response spectrum having a 2 percent probability of exceedance within a 50-yr. period.”

Here we use the +2 σ response spectrum at all periods, to facilitate comparison and since that has a ~2% probability of exceedance, given the scenario magnitude and distance.

The 150%-of-median deterministic cap is ignored here to allow comparison with other results.

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Selection approachSelection approach

Start with the NGA ground motion library (7038 horizontal components)

Eliminate records not meeting specified criteria (e.g., magnitude and distance ranges)

Select the 28 records that most closely matched the target spectra after scaling

If the average of the 28 spectra fell significantly below the target spectrum, perform some additional minor scaling

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Case 1 (Method Tag 9980)Case 1 (Method Tag 9980)No M/R/Mech. Restrictions

No filter frequency restriction

7038 records available

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0.2 T1 1.5 T1

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Case 2 (Method Tag 9981)Case 2 (Method Tag 9981)No M/R/Mech. Restrictions

Restricted filter frequencies

3454 records available (50%)

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Case 3 (Method Tag 9982)Case 3 (Method Tag 9982)6.5 < M < 7.6

No Dist./Mech. Restrictions


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Case 4 (Method Tag 9983)Case 4 (Method Tag 9983)0 < R < 30 km

No Mag./Mech. Restrictions


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Case 5 (Method Tag 9984)Case 5 (Method Tag 9984)Strike slip events only

No Mag./Dist. Restrictions


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Case 6 (Method Tag 9985)Case 6 (Method Tag 9985)6.5 < M < 7.6,

0 < R < 30 km

Strike slip events only

Target spectrum not always exceeded


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Case 9 (Method Tag 9976)Case 9 (Method Tag 9976)

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Set #4

6.5 < M < 7.6

0 < R < 30 km


Max scale factor = 2


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9 records available (0.1%)

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ObservationsObservations

Are the magnitude/distance/mechanism restrictions needed?

We know they affect spectral shape, but we are already specifying a target spectral shape

Median response spectra from events with differing magnitudes and distances

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Are scale factor restrictions needed?

They don’t seem to have an effect. Again, this may result from the target spectrum requirement

Note that no such restriction is given in the code

Is the one-record-per-event restriction needed?

It doesn’t seem to have an effect, and severely limits the available number of records


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Is the filter frequency limitation needed?

Presumably over-filtered motions will not match the design spectrum, so the target spectrum should ensure we have records with proper filtering (assuming that 0.2T to 1.5T are the only periods we need to worry about)


0 5 10 15 20 25 300

1000

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Maximum usable period [s]

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ConclusionsConclusions

Responses seem to be controlled by the target spectral shape, rather than the other selection criteria

This suggests that the choice of the target spectrum is a more important consideration than the choice of additional criteria

Benefit of the additional criteria: more “insurance” that you have appropriate record properties

Disadvantage of the additional criteria: a reduced number of records to chose from, meaning that you will not be able to match the target spectrum as closely

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Structural Responses – Preliminary Structural Responses – Preliminary

Results and ObservationsResults and Observations


Curt B. Haselton, PhD, PECurt B. Haselton, PhD, PE


California State University, ChicoCalifornia State University, Chico


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Detailed Review: Matching CMSDetailed Review: Matching CMS

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Point of Comparison


Median = 0.019POC = 0.019


Median: 1.01

c.o.v.: 0.20

Minimum: 0.76

Maximum: 1.51

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Median = 0.019POC = 0.019


Median: 1.01

c.o.v.: 0.20

Minimum: 0.76

Maximum: 1.51

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All methods aim to match the CMS one algorithm or another.

The predictions are all close to the POC, on average.

Comparison to Buildings A and D:

Trends are similar.

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Overall Median = 0.019POC = 0.019

10: CMS with Scaling [Baker]

Median = 0.0189

15 :Genetic Algorithm [Alimoradi, Naeim]

Median = 0.0192

24 :Semi-Automated Selection and Scaling

[Rathje, Kottke]

Median = 0.0197

45 :Design Ground Motion Library [Wang, Power,

Youngs]

Median = 0.0199

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Detailed Review: Matching CMS (#10, 15, Detailed Review: Matching CMS (#10, 15, 24)24)

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ED

P:

IDR

max

AllS

torie


Point of Comparison


POC = 0.019

Methods 10, 15, and 24:

Predictions agree with the POC consistently.

53

Detailed Review: Matching CMS (#45)Detailed Review: Matching CMS (#45)

10 10 10 10 15 24 24 45 45 45 450

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

12 3 4

1

2

1

2

3

4

Method Tag

ED

P:

IDR

max

AllS

torie


Point of Comparison


POC = 0.019

Average predictions agree well with the POC

[median = 0.0199].

However, there is more scatter in the prediction.

Let’s looks at the spectra to see if that explains it.

54


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g

]Scenario: M7, Method: 45, Building: C, Record Set: 1, Obj.: 4



Individual Records

Record Set: 1

Median MIDR = 0.014

55


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Record Set: 2

Median MIDR = 0.029

56


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Record Set: 3

Median MIDR = 0.021

57


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Record Set: 4

Median MIDR = 0.015

Small differences in spectra at T > T1 seem to correlate with predictions.

However, similar variations are present in

spectra for method 10, and the predictions do not vary

as much.

Is there another reason for the differences in the

Method 45 predictions, which is not shown in the

acceleration spectra?

58


Summary of Observations (same for Buildings C, A, and D):

All methods give predictions close to POC.

Methods 10, 15, and 24:

Predictions agree with POC consistently.

Method 45:

Average prediction agrees with POC.

There is more prediction variability.

Variability may be partially explained by differences in the

spectra, but it looks like spectra do not full explain the

differences.

Explanations?

59

Detailed Review: Proxy for Spectral ShapeDetailed Review: Proxy for Spectral Shape

57 57 57 57 58 58 58 58 30 31 31 31 31 20 20 20 200

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

1

2

3 41

3

4

1 2 3

4

1/7 1/7 1/7 5/7 3/7 3/7 10/28 2/7 3/7 1/7 1/7

Method Tag

ED

P:

IDR

max

AllS

torie


Point of Comparison


Overall Median = 0.022 (w/o 57-58)POC = 0.019


Median: 1.15

c.o.v.: 0.30

Minimum: 0.79

Maximum: 1.88

With 57-58 removed

57-58: Assume some error in our analyses, so excluded from

discussion for now.

60

Detailed Review: Proxy for Spectral ShapeDetailed Review: Proxy for Spectral Shape

57 57 57 57 58 58 58 58 30 31 31 31 31 20 20 20 200

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

1

2

3 41

3

4

1 2 3

4

1/7 1/7 1/7 5/7 3/7 3/7 10/28 2/7 3/7 1/7 1/7

Method Tag

ED

P:

IDR

max

AllS

torie


Point of Comparison


POC = 0.019

57-58: Assume some error in our analyses, so excluded from

discussion for now.

30-31: ε Selection with Sde(T1) Scaling [Tothong and Luco]

Median MIDR = 0.022

20: Selection based on M, R, ε, and Site Class [Skyers, Stewart, Goulet]

Median MIDR = 0.021

Overall Median = 0.022 (w/o 57-58)

Comparison to Buildings A and D:

Trends are similar.

61

Detailed Review: Proxy for Spect. Shape Detailed Review: Proxy for Spect. Shape (#31)(#31)

57 57 57 57 58 58 58 58 30 31 31 31 31 20 20 20 200

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

1

2

3 41

3

4

1 2 3

4

1/7 1/7 1/7 5/7 3/7 3/7 10/28 2/7 3/7 1/7 1/7

Method Tag

ED

P:

IDR

max

AllS

torie


Point of Comparison


POC = 0.019

30-31: ε Selection with Sde(T1) Scaling [Tothong and Luco]

Median MIDR = 0.022

Look at spectra for method 31 (objective 4).

Try to explain variability in predictions.

62


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

All 4x7 records.

The spectra match the CMS well on average.

Let’s look at spectra of individual sets….

63


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Set 1

64


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Set 2

65


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Set 3

66


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Set 4

Observation:

All 28 records match CMS well, but individual

sets of 7 have scatter. This explains scatter in

predicted response.

67


57 57 57 57 58 58 58 58 30 31 31 31 31 20 20 20 200

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

1

2

3 41

3

4

1 2 3

4

1/7 1/7 1/7 5/7 3/7 3/7 10/28 2/7 3/7 1/7 1/7

Method Tag

ED

P:

IDR

max

AllS

torie


Point of Comparison


POC = 0.019

20: Selection based on M, R, ε, and Site Class [Skyers, Stewart, Goulet]

Median MIDR = 0.021

Look at spectra…

68


10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

All 4x7 records. Individual sets of 7 look similar.

The spectra do not match the CMS.

They are higher at T < T1 and lower at T > T1.

Even so, the predictions agree with the POC.

This is the case for this building, and also Buildings A and D.

69

Detailed Review: Proxy for Spectral Shape Detailed Review: Proxy for Spectral Shape

Summary of Observations:

Predictions are typically 10-15% higher than POC on average.

Methods 30-31 [prediction is 15% above POC]:

Spectra match CMS on average, though each set of 7 has

variability.

Variability in spectra leads to variability in MIDR prediction.

Method 20 [prediction is 10% above POC]:

Spectra consistently do not match the CMS.

Even so, this gives consistent predictions that are close to

the POC. This also is true for Buildings D and A.

Why good/consistent predictions when the spectral shape is

distinctly different from CMS?

70

Detailed Review: Inelastic-Based MethodsDetailed Review: Inelastic-Based Methods

A

A

A

aOverall Median = 0.022POC = 0.019


Median: 1.14

c.o.v.: 0.19

Minimum: 0.76

Maximum: 1.58

26-27: Sdi [Tothong and Luco]

Median MIDR = 0.024

6: Vector of Record Properties Identified by Proxy [Watson-Lamprey]

Median MIDR = 0.019

35-35: IM1I&2E [Luco and Tothong]

Median MIDR = 0.022

11: Inelastic Response Surface Scaling [Shantz]

Median MIDR = 0.023

71

Detailed Review: Inelastic Methods (#26-Detailed Review: Inelastic Methods (#26-27)27)

A

A

A


26-27: Sdi [Tothong and Luco]

Median MIDR = 0.024

10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g

]

Scenario: M7, Method: 27, Building: C, Record Set: Combined, Obj.: 4



Individual Records

72

Detailed Review: Inelastic Methods (#6)Detailed Review: Inelastic Methods (#6)

A

A

A


6: Vector of Record Properties Identified by Proxy [Watson-Lamprey]

Median MIDR = 0.019

10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g

]




Individual Records

73

Detailed Review: Inelastic Methods (#34-Detailed Review: Inelastic Methods (#34-35)35)

A

A

A


35-35: IM1I&2E [Luco and Tothong]

Median MIDR = 0.022

10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g

]




Individual Records

74


A

A

A



Median MIDR = 0.023

10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g




Individual Records

Sets 3-4: Includes consideration of 2nd mode

75


A

A

A



Median MIDR = 0.023

10-1

100

101

10-2

10-1

100

101

Period [sec]

Spe

ctra

l Acc

eler

atio

n [g

]




Individual Records

Sets 1-2: No consideration of 2nd mode

76

Detailed Review: Inelastic MethodsDetailed Review: Inelastic Methods

Summary of Observations:

Predictions are typically 15% higher than the

POC, on average.

Not all spectra pass through Sa(T1) target.

Consideration of higher mode seems to help

prediction.

77

Summary of ResultsSummary of Results

Comparison of results for Buildings A and D

Median(MIDR/POC)Building T1

(sec)Sa(T1) UHS CMS

*Proxy (i.e. ε)

Inelastic

Building C (20-story RC frame) 2.63 1.48 1.26 1.01 1.15 1.14

Building A (4-story RC frame) 1.00 1.48 -- 1.05 1.05 1.17

Building D (12-story RC wall) 1.20 1.17 -- 0.94 1.09 1.00

* With methods 57 and 58 removed. Averages: 1.38 1.26 1.00 1.10 1.10

78

DiscussionDiscussion To reiterate the purpose of this time:

To obtain feedback and insights from the group (preliminary

results, approach, etc.).

To ensure that we correctly interpret the various methods.

To begin the process of coming to a collective consensus.

Discussion/Comments/Questions/Suggestions:

What are your thoughts on the results and possible explanations

for what we have seen?

What are we missing, or what have we not bee considering that we

should?

What do we need to address as we to refine and write-up the

findings of this study?

Other comments, suggestions, questions, discussion?

1 Structural Responses – Preliminary Results and Observations PEER GMSM Program Workshop, Richmond...

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