Action 4.2.2 : Characterizing variability and model uncertainties

Technical Issue.

Up to now, site response calculations usually considered a uniform Vs per layer and the ground propertie variability was accounted for by shifting the modulus value of the whole layer by 2 coefficients around the best estimate value (typically 2/3 and 3/2). This approach poorly represents the reality nor the effects that a spatial variability have on the ground motion. The objective of this task is to develop and/or improve methodologies to account for 1D/2D/3D variability and to assess modelling uncertainties.

Proposed Approach

1. Ground variability into 1D soil column calculations.
2. Characterizing 2D variability and calibrating attenuation at high frequencies
3. Numerical strategy to properly account for the variability in 2D and possibly in 3D models
4. Methodology to properly assess the uncertainties of the models and predictive capabilities of the models, especially when few field data is available
5. Quantifying uncertainties related to empirical and numerical approaches for 2D site effect evaluation in low seismicity areas

Deliverable

Methodology to characterize the variability of a site.