Analysis and Modeling of SSI in Bridge Support Structures (PhD Thesis)
Author: Payman K. Tehrani | Size: 3.6 MB | Format:PDF | Quality:Original preprint | Publisher: University of California, Los Angeles | Year: 2009 | pages: 231
ABSTRACT
The p-y method is an established analysis tool for lateral response of piles. Existing soil lateral load-displacement (or p-y) backbone curves have been calibrated with tests on small-diameter, linearly elastic piles. The first portion of this study is devoted to obtaining several new p-y curves by using data from three solitary reinforced concrete shafts embedded in stiff clay and tested to failure under lateral loading. These new curves are shown to differ from the standard curves, primarily in capacity: For a 6ft-diameter free-head specimen, the new curve reaches a load capacity that is 60% higher than the standard curve; for a 2ft-diameter free-head shaft, the new curve is 20% weaker; and for a 2ft-diameter fixed-head shaft, the new curve is 100% stronger than the existing standard.
In the second part of this study, the calibrated p-y model of the 2ft-diameter fixed-head specimen, and a validated finite element model of a group of nine piles are utilized to determine "group efficiency factors." These scaling factors are found to depend on the magnitude of lateral pile-cap displacement. The efficiencies are less than unity when the passively resisting soil wedges in front of the piles interfere with each other—for the same lateral displacement, a pile in the group generates a resisting force that is less than that of a solitary pile. Usually dubbed as the "shadowing effect," this behavior is observed up to intermediate levels of lateral pile-cap displacement. The group efficiencies tend to unity as the displacement increases.
The third part explores abutment-backfill interaction in bridges. This effect can significantly influence the seismic response of a bridge. Both log-spiral hyperbolic (LSH) and finite element models are validated using data from several abutment tests. Extensive parametric studies are carried out using the LSH model, which is more amenable for this task than the finite element model because of its computational efficiency. Results are used to devise hyperbolic equations to represent the lateral load-displacement backbone curves of abutments as an explicit function of wall height and the backfill soil's physical parameters. This physically parameterized hyperbolic formula is amenable for routine seismic response simulations of bridges.
Advisor: Professor Ertugrul Taciroglu
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SSI and Its Roles in Performance-Based Seismic Analysis of Shear Wall Structures (PhD Thesis)
Author: Yuchuan Tang | Size: 3.2 MB | Format:PDF | Quality:Original preprint | Publisher: University of California, Los Angeles | Year: 2009 | pages: 287
ABSTRACT
In order to systematically assess the complex soil-structure interaction (SSI) effects on the seismic responses of shear wall structures, this dissertation deals with several critical and inter-related topics under the framework of performance-based earthquake engineering. Firstly, the study develops improved pulse representations for earthquake ground motions that govern the peak structural responses. Based on rigorous dimensional analysis, the dimensionless Il-response spectra are derived for both linear and bilinear SDOF systems. They are shown to be congruent with the corresponding (dimensional) response spectrum in bi-logarithmic plotting. This leads to a novel approach to identify pulse parameters that match simultaneously the kinematic characteristics and the response spectrum of the original ground motion. The improved pulse representations can potentially be used as the intensity measures of earthquake ground motions. Secondly, the SSI effects of lumped soil-foundation-structure interacting (SFSI) systems are investigated through the dimensional analysis with pulse motions as input.
The dimensionless terms that govern the interactive behavior of SFSI systems are derived. The SSI effects are related explicitly and directly to the characteristics of input ground motions and the properties of SFSI systems. The conditions under which the SSI effects amplify or reduce the structural responses are also identified. Subsequently, dynamic responses of strip foundations bonded on linear or nonlinear soil half-space are investigated using the finite element method. The dynamic foundation responses are found to depend on the amplitude and frequency of input motion, foundation geometry, and soil properties. The energy dissipation through radiation damping for nonlinear soil case is reduced and can be quantified with two alternative factors related to the yielding of soil medium.
Finally, the SSI effects are evaluated for a realistic shear wall structure using the probabilistic seismic demand analysis where the nonlinear hysteretic behavior of shear walls and foundations are accurately modeled. Either the inelastic spectral displacement or the pulse representation is adopted as the intensity measure of input ground motions. The damage probability of the shear wall generally decreases when the SSI effects are considered for this case study.
Advisor: Professor Jian Zhang
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The purpose of this study is to investigate the P-Delta effect on bridge piers with consideration of soil-structure interaction effect. The traditional P-Delta effect was calculated assuming the base of the structure is fully fixed. However, all structures in real life are supported by soil, and soil is deformable. Therefore, under wind or earthquake loads, the additional lateral deflection of a bridge pier
caused by the deformation of the soil, which supports the pier, should be considered. The traditional method regarding the computation of the deflection of a pier caused by wind or earthquake loads does not take soil-structure interaction effects into account. In this study finite element analysis method will be used to investigate the additional overturning moment introduced by the soil-structure interaction effect.
Advisor: Assoc.Prof. Dr. J. Kent Hsia
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Dear Friends
i need paper
"Settlemet of Raft Foundations"
by Kay.J.N and Cavagano.R.L
Journal of Geotechnical Engineering division of ASCE 1983
vol 109 pp 1367-1382
could anyone share it?
thanks in advance
with best regards
mz55
This book is an introduction to surgery theory: the standard classification method for high-dimensional manifolds. It is aimed at graduate students, who have already had a basic topology course, and would now like to understand the topology of high-dimensional manifolds.
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Author: Romeyn Henry Rivenburg | Size: 5.2 MB | Format:PDF | Quality:Scanner | Publisher: American Book Company | Year: 1914 | pages: 80 | ISBN: B006CN21OW
The object of this book is to provide a thorough and effective review that is necessary in order to prepare college candidates for the entrance examinations and for effective work in the freshman year in college. This is the 1914 edition.
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Hello
I had been developing a spreadsheet for the calculation of Elastic settlements in foundations on granular soils using theory of Elasticity . I had problem for calculating "Depth Influence Factor" . I can only find a chart in literature generated using Fox's (1948) equation from where every time i had to read values and insert in the cell.
Can any one guide me that how can I find this Fox's equation or any other alternate way to get this factor without reading chart for every time.
Posted by: ziggywas1 - 01-22-2012, 08:14 AM - Forum: Archive
- No Replies
I'm looking for the following parts of ISO 17123 Optics and optical instruments - Field procedures for testing geodetic and surveying instruments:
Part 1 - Theory
Part 3 - Theodolites
Part 4 - Electro-optical distance meters
Part 5 - Electronic tacheometers
Any edition (standard, draft, for comment) would be appreciated.
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