GMSM Methodologyand Terminology

Christine Goulet, UCLAGMSM Core Members

Plan

Methodology overviewMethod ObjectivesSolicitation InformationTerminology

Methodology Propose scenarios (M, r)

M=7, r=10 km, +22 M=7.5, r=10 km, +11

Select a series of structures (buildings) to be analyzed

Building Stories Type Compliance T1 (s)

A 4 Modern special moment frame

2003 IBC 0.97

B 12 Modern special moment frame

2003 IBC, ASCE7-02, ACI 318-02

2.01

C 20 Modern special moment frame

2003 IBC, ASCE7-02, ACI 318-02

2.63

D 12 Modern (ductile) planar shear wall

None specifically, but consistent with modern planar wall

design

1.20

Methodology Select pertinent Engineering Demand

Parameters (EDPs) Maximum Inter-Story Drift Ratio (MIDR)Others considered, to be discussed:

Peak Floor AccelerationBase shear

Request ground motion suites for each method of GMSM

Perform the nonlinear dynamic analyses (NLDA)

Compute the distribution of the selected EDP response

Methodology

Compute the Point of Comparison (POC)Rerun structural simulationsBased on larger set of records corresponding to

the scenarioPerform the nonlinear dynamic analyses (NLDA)Compute the distribution of the selected EDP

responsePDF

EDP(=MIDR)

POC

Median

Methodology Analysis of results, observations and conclusions

Compare results of suites with POCDraw conclusions and recommendations

PDF

EDP

Method Z

POC

Method Y

… Repeat the whole procedure for other structures and scenarios …

Method objectivesMIDR for a given M, r, S, and F

1. Full distribution2. Median only

MIDR for a given M, r, S, F and Sa(T1)

3. Full distribution4. Median only

Applications: • Earthquake scenarios• PSHA-type integration for

building response

Applications: • Design of new buildings• Rehabilitation of existing

buildings• Performance-Based

evaluation

Solicitation this year

Objectives 3 & 4: predict the maximum interstory drift

Building B, scenario M7 and M7.5 Buildings C and D, scenario M7 Building A, scenario M7 Four sets of 7 records

To match building code requirements (7)To allow larger suites for statistics and research

purposes (28)

19 methods46 variants

Nomenclature – EDP distributions

Median: 50 % of entries above, 50% below Mean: sum of all entries divided by the number of entries

PDF

EDPMeanMedian

Normal distribution Skewed distribution

MedianMean EDP

Nomenclature – EDP distributions

Skewed (lognormal) distribution

0

0.5

1

PDF

CDF

Probability

EDP

98th percentile

Nomenclature – ground motions

Standard deviation , and Epsilon

StandardDeviation,

Median,

Sa(T1)

PDF

Generic GMPEMedian

Median + 1 Standard Dev.

M=7R=10 kmSoil

Sa(g)

T (s)T1

On the scenarios M 7-7.5 within 20 km often controls the

hazard in urban CA Why +2?

To push the structures well in the NL range It is not unreasonable

Relative Contribution

20%

10%

0%

5.0-5.5

5.5-6.0

6.0-6.5

6.5-7.0

7.0-7.5

7.5-8.0

8.0-8.5

Seismic Hazard Disaggregation Sa(1s) = 0.82g

2% in 50 years (2475)

0 < < 0.5

0.5 < < 1

1 < < 2

2 <

Legend

< -2

-2 < < -1

-1 < < -0.5

-0.5 < < 0

East Bay• 2% in 50 average: 1.6• 0.5% in 50 average: 2.1

Relative Contribution

20%

10%

0%

0-10

10-2

0

20-3

030

-40

40-5

0

50-6

0

60-7

0

70-8

0

80-9

090

-100

100-

1000

5.0-5.5

5.5-6.0

6.0-6.5

6.5-7.0

7.0-7.5

7.5-8.0

8.0-8.5

Distance (km)

Magnitu

de

Sa(1s) = 0.55g 10% in 50 years (475)

0 < < 0.5

0.5 < < 1

1 < < 2

2 <

Legend

< -2

-2 < < -1

-1 < < -0.5

-0.5 < < 0

Seismic Hazard Disaggregation