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Devi, Dipika
- Finite Element Analysis of Strip Footing in Layered Soil Using MATLAB
Authors
1 Department of Civil Engineering, North Eastern Regional Institute of Science and Technology, Nirjuli, Arunachal Pradesh, IN
Source
International Journal of Innovative Research and Development, Vol 5, No 9 (2016), Pagination: 28-32Abstract
A finite element analysis program is written using the powerful interactive language MATLAB. The program is used to analyze the deformation characteristics of soil under a strip footing. The soil is modeled as layered with uniform elastic constants for each layer. The results of the layered soil are compared with that of an equivalent uniform soil. The elastic constants of the equivalent uniform soil are determined by taking the weighted average of that of the layered soil. The analysis is also performed by modeling the constitutive behaviour of the equivalent uniform soil to be nonlinear. The nonlinear hyperbolic model is used for this purpose and the results are compared with that of linear analysis. The results show that analysis with a linear equivalent uniform soil may underestimate the settlement and overestimate the allowable loads.
Keywords
MATLAB, Strip Footing, Layered Soil, Non Linear Soil, Bearing Capacity.Full Text
- Nonlinear Solution Techniques and Load Stepping Schemes for Modified Cam Clay Model
Authors
Source
International Journal of Innovative Research and Development, Vol 5, No 8 (2016), Pagination: 238-243Abstract
Critical state models are developed from the application of plasticity to soil mechanics and they are the most widely used soil constitutive model. The model is highly nonlinear in nature and in finite element analysis, with a nonlinear material model; an iterative and incremental scheme is required to solve the resulting system of nonlinear equations. Variety of incremental and iterative schemes are developed in the past to integrate the load-displacement curve for nonlinear material models and each of them has advantages and limitations over other while using with a specific constitutive model. As critical state models are nonlinear in nature in the elastic as well as plastic parts of the constitutive relation, the performance of different load stepping schemes for finite element analysis particularly with critical state models is to be done and can be an active area of study. In the present study the review of the literature on the use of various nonlinear solution techniques and load stepping schemes used for general plasticity models and critical state soil constitutive models are carried out. It is observed that very little literature is available which study the influence of the nonlinear solution techniques and load stepping schemes on the solution of nonlinear finite element problems with critical state models. From the available literature it can be concluded that critical state models are very sensitive to the load step size and iteration tolerance as well. A comparative study on the performance of some of the mostly used nonlinear solution techniques and load stepping schemes with modified cam clay model is also carried out. The solution schemes which are included in the study are: Newton-Raphson methos, Modified Newton-Raphson methos, Accelerated modified Newton-Raphson methods and Arclength method. The study reveals that the performance of Arclength method as compared to other methods is better while using them with modified cam clay model.
Keywords
Critical state models, cam clay model, finite element analysis, nonlinear solution techniques, load stepping schemesFull Text