Although there exist some consensus regarding seismic soil liquefaction assessment
of free field soil sites, estimating the liquefaction triggering potential beneath
building foundations still stays as a controversial and difficult issue. Assessing
liquefaction triggering potential under building foundations requires the estimation of
cyclic and static stress state of the soil medium. For the purpose of assessing the
effects of the presence of a structure three-dimensional, finite difference-based total
stress analyses were performed for generic soil, structure and earthquake
combinations. A simplified procedure was proposed which would produce unbiased
estimates of the representative and maximum soil-structure-earthquake-induced
iv
cyclic stress ratio (CSRSSEI) values, eliminating the need to perform 3-D dynamic
response assessment of soil and structure systems for conventional projects.
Consistent with the available literature, the descriptive (input) parameters of the
proposed model were selected as soil-to-structure stiffness ratio, spectral
acceleration ratio (SA/PGA) and aspect ratio of the building. The model coefficients
were estimated through maximum likelihood methodology which was used to
produce an unbiased match with the predictions of 3-D analyses and proposed
simplified procedure. Although a satisfactory fit was achieved among the CSR
estimations by numerical seismic response analysis results and the proposed
simplified procedure, validation of the proposed simplified procedure further with
available laboratory shaking table and centrifuge tests and well-documented field
case histories was preferred. The proposed simplified procedure was shown to
capture almost all of the behavioral trends and most of the amplitudes.
As the concluding remark, contrary to general conclusions of Rollins and Seed
(1990), and partially consistent with the observations of Finn and Yodengrakumar
(1987), Liu and Dobry (1997) and Mylonakis and Gazetas, (2000), it is proven that
soil-structure interaction does not always beneficially affect the liquefaction
triggering potential of foundation soils and the proposed simplified model
conveniently captures when it is critical.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12610285/index.pdf |
| Date | 01 December 2008 |
| Creators | Unutmaz, Berna |
| Contributors | Cetin, Kemal Onder |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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