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Title: Non-linear finite element analysis of shallow footings
Author: Abdullah, W. S.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1983
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This research involves the analysis of any kind of foundation is considered satisfactory unless proper consideration is paid to the foundation materials i.e. soil. The objective of this research has therefore been two-fold. The first aspect is the analysis of footing problems, whilst the other has been the introduction, modificaion, and implementation of more realistic soil models. Several footing problems have been analysed. A method of predicting the Load-Settlement relationship for shallow footings acting on sandy soils has been proposed. The proposed method is based on several features characteristic of any Load-Settlement relationship namely the elastic range, the ultimate load, and the elastic-plastic region. The proposed method is very simple to use either by manual calculation or fully computerized computation. The obtained results are compared with results obtained from elastic/viscoplastic finite element analysis on very carefully designed mesh. Shakedown principles are also presented with some examples on the shakedown analysis of footings acting on homogeneous and non-homogeneous clays. Shakedown/incremental collapse anticipation was carried out using a criterion based on Melan's theory, whilst Capourso's theory provided the bound on settlement when the shakedown state is reached. The determination of the contact pressure distribution underneath rigid footings has been presented by using different lines of approach. The intention was also to evaluate and verify Schultz's method for use in different soils in the light of the highly credible approach element method. The second aspect of the research is the implementation of a work-hardening elasto/ lactic model into the viscoelastic algorithm for the analysis of footing on sandy soils. Bearing capacity predicted by the use of this model is compared with other analytical methods. Some comparisions with the Coulomb model are also presented. A tangential non-linear elastic/viscoplastic model has been introduced as a realistic approach for the analysis of all kinds of soils and sandy soils in particular. This approach proved to represent soil behavior more accurate and realistically as has been demonstrated by the presented examples. The efiosen approach of implementing this model is based on the capability of handling all kind of circumstances associated with a soil/tooting system such as the influence of the pre-loading or the initial state of stress. The choice is also based on the economy of the obtained solution. The compatibility of the proposed model with the physical behavior of soils has substantial numerical advantages. Four no-tension criteria have been proposed. Their physical and numerical aspects have been discussed and examined with some examples. The choice of the no-tension criterion used throughout this thesis has been based on toqical, as well as numerical considerations. The results obtained with this criterion concerning the region of tensile stresses in a vertically pulled Anchor are compared with a sophisticated soil-structure interaction method proposed by Davis and I. Rowe. Finally a technique for the analysis of rigid footings based on physical considerations of soil behavior is introduced. A number of examples have been presented and substantial numerical improvement on the number of viscoplastic iterations has been demonstrated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available