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first a digression The POC Ranking the Methods. Jennie Watson-Lamprey October 29, 2007. A Digression. Top 20 MIDR Values. Top 20 MIDR Values. Not a lot of overlap. We don’t know going into the problem which ground motions are high and which are low. Top 20 MIDR Values.

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first a digression the poc ranking the methods

first a digressionThe POC Ranking the Methods

Jennie Watson-Lamprey

October 29, 2007

top 20 midr values1
Top 20 MIDR Values
  • Not a lot of overlap.
  • We don’t know going into the problem which ground motions are high and which are low.
top 20 midr values2
Top 20 MIDR Values
  • If we’re after the median EDP, we use a GMSM method to get rid of the outliers
  • If we’re after the distribution of EDP, we don’t want to throw away the outliers.
top 20 midr values3
Top 20 MIDR Values
  • The point isn’t to identify the outliers.
  • The point is to figure out which GMSM method does it for you.
calculating the point of comparison
Calculating the Point of Comparison
  • Time series from a bin of M, R
    • Should work for a median
    • Too much variability!
  • Time series from a bin of M, R corrected for the difference between the recorded event and the design event
    • Not enough records to push the structure into the nonlinear range -> not a good estimator of rare response values
calculating the point of comparison1
Calculating the Point of Comparison
  • Current Method:
    • Run scaled and unscaled time series through a structural model
    • Perform a regression on a response parameter using time series properties (spectral acceleration)
    • Use predictive equations to define the joint distribution of the time series properties
    • Integrate the regression over the joint distribution
    • This gives a distribution of a response parameter
method for estimating point of comparison
Method for Estimating Point of Comparison
  • A suite of records from Mw6.75-7.25, Rrup 0-20km events was developed. A total of 98 records were distributed to the group June 26th.
  • The suite is run through each model using scale factors of 1, 2, 4 and 8.
  • A model of the desired structural response parameter using properties of the input time series (e.g. Sa(T1), Sa(2T1), duration, etc.) is developed.
method for estimating point of comparison1
Method for Estimating Point of Comparison
  • The EDP model is checked to ensure that there is no bias with scale factor.

- This is only a test for the limited M,R range represented by the 98 selected recordings

  • Models for the record properties that affect response are developed using the full PEER database and correlations between properties.
  • Combining the models in step 5 gives the joint pdf of record properties
  • Using the joint pdf of record properties and the model for building response based on those record properties, the pdf of structural response for a M7, Rrup=10km earthquake is calculated.
building a regression
Building A - Regression
  • Perform a regression to determine probability of collapse - Here it’s 0.
  • Perform a regression to determine median and variability of MIDR.
  • Regression is based on spectral values at a number of periods.
ranking of methods
Ranking of Methods
  • Focus on suites of 7-ground motions
  • 10 contributors provided 4 suites of 7 ground motions for buildings A, C & D.
  • Develop an estimated distribution of predictions
  • Use the estimated distribution and the goal of the analysis to develop a statistic for ranking
ranking statistic
Ranking Statistic
  • Goal: Accurate estimate of MIDR | M, R, Sa
  • Statistic: P ( -0.1 < X < 0.1)
ranking statistic1
Ranking Statistic
  • Goal: Minimize under-estimation of MIDR | M, R, Sa
  • Statistic: P ( X > 0 )
ranking of methods1
Ranking of Methods
  • Ranking is dependent on analysis goal.