Award Date

1-1-2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

First Committee Member

Barbara Luke

Number of Pages

210

Abstract

Deep sediment columns play a significant role in defining surface response to earthquakes. For the Las Vegas basin (Nevada, U.S.), the basin sediments are capable of amplifying ground motions by a factor of up to 5 to 10 with respect to motions recorded at near-rock sites at the edges of the basin, over the period range 0.3 to 5 sec; A one-dimensional (1-D) equivalent-linear model is used to study the impact of sediment columns on surface response. The 1-D model is optimally parameterized through iterative assessment to select the depth to halfspace so that the projected response spectrum best matches the measured or anticipated response. This approach compensates for intrinsic uncertainties associated with shear wave velocity and dynamic soil properties at great depths; The established procedure adequately captured ground motion amplification in the period range 0.2 to 1 sec, which has engineering significance for 2- to 10-story structures. The appropriate depth to halfspace was 400 m; Monte-Carlo simulation can be used to generate bounding response spectra. This approach is especially useful for site response studies for deep deposits (>200 m); Shear wave velocity profiles can be effectively and efficiently characterized to significant depths (to 300 m or more in Las Vegas) using combined active- and passive-source surface wave measurements; Parametric studies using Monte Carlo simulation revealed that (1) a high VS inclusion can amplify as well as deamplify the surface response; and (2) site response analyses using V S averaged over the upper 30 m can underestimate surface response; Earthquake hazard in the Las Vegas basin is significant. Six faults are found to have high earthquake potential. The basin can be zoned in two major site response units according to predominant near-surface grain size. Bounding response envelopes are developed for each zone based on a deterministic site response projection, using the 1-D model, lithologic and shear wave velocity databases, and Monte-Carlo simulation. The upper bound values of peak ground acceleration and peak spectral acceleration for the Las Vegas basin are on the order of 0.3 g and 1 g, respectively.*; *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office.

Keywords

Basin; Columns; Deep; Earthquake; Earthquake Las Vegas Basin; Las Vegas Basin; Microzonation; Projections; Responses; Sediment; Sediment Columns; Site Response; Vegas

Controlled Subject

Civil engineering

File Format

pdf

File Size

5048.32 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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Rights

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