Special Topic

Description

Title - Seismic Site Response: Theory, Modelling, and Incorporation in Seismic Design and Assessment

Fundamental concepts of wave propagation that influence seismic site response. Case studies that illustrate the phenomenon, including examples of linear and nonlinear site effects, and basin effects. Acquisition and derivation of input parameters for geotechnical site response analysis using field methods, and empirically-based and lab-based correlations. Modelling of linear and nonlinear site response analysis using empirically-based methods and simulations. Commonly used and more sophisticated site proxies for estimating site response empirically, for implementation into building codes and regional ground motion characterisation. Methods for non-ergodic modelling of site response in seismic hazard analysis, including approaches utilised in critical infrastructure projects globally.


• Theme 1: Site-Response Phenomena
o Introduction to site effects, including demonstrative global case studies. Presentation of fundamental concepts in site response such as: wave propagation, impedance, reflection, and refraction.

• Theme 2: Geotechnical and Geophysical Site Characterisation for Site Response
o Discussion of invasive and non-invasive approaches for collecting site characterisation data for site response.  CPT, SPT, VS profiles, VS30, and recording earthquakes and microtremor data for H/V ratios.

• Theme 3: Theoretical Modelling of Site Effects
o Modelling via closed-form solutions (i.e., linear and equivalent linear methods) and 1D-3D wave propagation modelling, including nonlinear analyses. Calculation and interpretation of transfer functions for various scenarios. Interrogation of the 1D assumption in site response, including comparison of predicted and observed transfer functions from case studies to illustrate multidimensionality in site response. Detailed discussion on required input parameters for nonlinear site-response analysis. Instructional tutorial on using DeepSoil software for site response.

• Theme 4: Site-Response Prediction via Parameters/Proxies (Part I)
o Introduction of commonly used site parameters, VS30, Z1.0, Z2.5 and f0, in site-response estimation. Discussion on predictions via empirical ground-motion models (i.e., the site-response functions in such models and how they attempt to capture physics).  Discussion on site-response factors in seismic design codes (for those codes that still use site factors, compared with those codes, e.g., new NZ code, which just directly give spectra for different sites from PSHA results).

• Theme 5: Site-Response Prediction via Parameters/Proxies (Part II)
o Discussion on prediction of site response in regional ground-motion characterisations which naturally use easy-to-obtain site proxies, e.g., topographic slope and surface roughness that can be derived from digital elevation models. Introduction of more refined attempts to quantify site response via 'new' proxies such as H/V ratio of microtremors and other frequency-dependent vectors.

• Theme 6: Site-Response in Seismic Hazard Analysis
o Brief introduction to PSHA. Non-ergodic modelling for site response via the consideration of measurements or use of site-response analysis. Development of site amplification functions using observations, simulations or empirical methods, and application of the functions to modify hazard calculations (e.g., the convolution method). Introduction to the scaled back-bone approach used in seismic hazard analyses of critical infrastructure.