Date of Award

8-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil Engineering

Committee Member

Dr. Qiushi Chen, Committee Chair

Committee Member

Dr. C. Hsein Juang, Co-Chair

Committee Member

Dr. Ronald Andrus

Committee Member

Dr. Jie Zhang

Abstract

The ground motion parameters such as amplitude, frequency content and the duration can be affected by the local site condition and may result in amplification or de-amplification to the original bedrock motion. Shear wave velocity is an important site parameter to describe the site condition and is widely used in estimating site response, classifying sites in recent building codes and loss estimation. This dissertation is aimed at: modeling the spatial variation of shear wave velocity using geostatistical tools; improve the random field framework for estimating soil properties to account for multiple sources of data; develop finite element model to qualify the uncertainty propagation in dynamic site response; introduce the response surface concept into seismic hazard analysis and quantifying the uncertainty propagation in dynamic site response caused by the variation of shear wave velocity and design parameters. To model the spatial variation of shear wave velocity, a multiscale random field-based framework is presented and applied to map Vs30 - the time-averaged shear wave velocity in the top 30 meters of subsurface material - over extended areas. In this framework, the random field concept is employed to model the horizontal variation of shear wave velocity. Suzhou Site is selected as the research area and its measured shear wave velocity data is combined with the U.S. Geological Survey (USGS) slope-based Vs30 map for mapping the Vs30 around whole research area. Moreover, a different method of integrating multiple sources of data is used and tested based on a synthetic digital field. To quantify the uncertainty propagation in dynamic site response caused by the variation of shear wave velocity, the finite element method (FEM) is developed and combined with random field realizations of shear wave velocity profiles. A viscoelastic constitutive model is implemented in the FEM model to account for the non-linear hysteresis response of subsurface materials under cyclic loadings. The analyzed site responses, as well as the input parameters generated with Monte Carlo simulations (MCS), are then used to study the peak acceleration at site surface subjected to a given input seismic wave. Finally, the response surface method and the first order second-moment method (FOSM) are integrated into dynamic site response analysis to characterize the variation of site performance caused by spatial variation of shear wave velocity. Through illustrative examples, the effectiveness, advantage, practicability, and significance of improved random field framework and developed uncertainty propagation evaluation methodology are demonstrated.

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