Review and Validation of Stochastic Ground Motion Models: which one does it better?

TL;DR

This paper reviews and validates hierarchical stochastic ground motion models (GMMs), focusing on their optimal configuration and demonstrating their ability to generate realistic ground motions comparable to real data.

Contribution

It introduces a hierarchical formulation of GMMs with an optimal MFWNM and compares copula models, providing a validated framework for realistic ground motion simulation.

Findings

Hierarchical GMMs produce statistically compatible ground motions with real datasets.

An 11-parameter MFWNM with copula models offers high accuracy with fewer parameters.

Validated models accurately reproduce key intensity measures and response spectra.

Abstract

Stochastic ground motion models (GMMs) are gaining popularity and momentum among engineers to perform time-history analysis of structures and infrastructures. This paper aims to review and validate hierarchical stochastic GMMs, with a focus on identifying their ''optimal'' configuration. We introduce the word ''hierarchical'' as its formulation contains two steps:(1) selecting a modulated filtered white noise model (MFWNM) to replicate a target record and (2) constructing a joint probability density function (PDF) for the parameters of the selected MFWNM, accounting for the record-to-record variability. In the first step, we review the development of MFWNMs and explore the ''optimal'' modeling of time-varying spectral content. Specifically, we investigate different frequency filters (single- and multi-mode) and various trends (constant, linear, and non-parametric) to describe the filters' time-varying properties. In the second step, the joint PDF is decomposed into a product of marginal distributions and a correlation structure, represented by copula models. We explore two copula models: the Gaus-sian copula and the R-vine copula. The hierarchical GMMs are evaluated by comparing specific statistical metrics, calculated from 1,001 real strong motions, with those derived from their corresponding synthetic dataset. Based on the selected validation metrics, we conclude that (1) Hierarchical stochastic GMMs can generate ground motions with high statistical compatibility to the real datasets, in terms of four key intensity measures and linear- and nonlinear-response spectra; (2) A parsimonious 11-parameter MFWNM, incorporating either the Gaussian copula or the R-vine copula, offers sufficient and similar accuracy.