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Dissertation
Stress-deformation behavior of footing foundations
Doctor of Philosophy (Ph.D.), Drexel University
1999
DOI:
https://doi.org/10.17918/00008735
Abstract
A rational method for studying the fundamental aspects of the stress-deformation behavior of footing foundation systems on sand is proposed. This method incorporates a newly developed constitutive model which captures the single most important aspect of soil behavior in general, and sand in particular: the increase in stiffness due to confinement. This unique property makes soil stronger under certain applied loads. The constitutive model is based on the results of isotropic compression tests. It traces the increase in stiffness due to loading by describing the instantaneous bulk modulus in terms of the effective mean stress or volumetric strain levels and two hyperbolic constants, namely the initial bulk modulus and the ultimate volumetric strain. The nonlinear stress-strain relationships of the proposed constitutive model are incorporated into a comprehensive finite element analysis procedure for footing foundations. The solution process starts by calculating the initial state of stress for each element and performing a linear elastic analysis. Due to the linearization errors, the strains and stresses based on equilibrium will not agree with the nonlinear isotropic stress-strain relationships. This results in unbalanced loads. The solution is repeated using a combined incremental-iterative method until the equilibrium condition and the isotropic material stress-strain relations are simultaneously satisfied. Verification of the proposed constitutive model and analysis procedure is achieved by: (1) simulating the stress-strain curves generated in isotropic compression tests; (2) modeling two-, and three-dimensional systems of small-scale, strip and spread footings and checking the predicted settlements against the experimentally measured ones; and (3) comparing the analysis findings with elasticity-based finite element as well as traditional settlement prediction methods.
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Details
- Title
- Stress-deformation behavior of footing foundations
- Creators
- Bashar S. Qubain
- Contributors
- Joseph Paul Martin (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xv, 187 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Engineering (1970-2026); Drexel University
- Other Identifier
- 991021889069304721