http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1907 Bearing capacity calculations are an important part of the design of foundations. Most of the terms in the bearing capacity equation, as it is used today in practice, are empirical. Shape factors for square and rectangular footings could not be derived in the past because three-dimensional bearing capacity computations could not be performed with any degree of accuracy. Likewise, depth factors could not be determined because rigorous analyses of foundations embedded in the ground were not available. In this paper, the bearing capacities of strip, square, circular and rectangular foundations in clay are determined rigorously based on finite element limit analysis. The results of the analyses are used to propose rigorous, definitive values of the shape and depth factors for foundations in clays. These results are helpful in reducing the uncertainties related to the method of analysis in bearing capacity calculations, paving the way for more cost-effective foundation design. 2010-04-27T06:58:02.965Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1339 This paper describes a new technique for computing the lower bound limit loads in unreinforced masonry shear walls under conditions of plane strain. From a macroscopic point of view, masonry displays similar behaviour to jointed rock or reinforced earth, which have already been successfully modelled using the lower bound theorem. The overall behaviour of the masonry shear wall is controlled by the mechanical properties of the intact unit (brick/block) and the discontinuities or joints, as well as the relative positions and orientation of the joint sets. As a result, masonry needs to be treated as an anisotropic, inhomogeneous material. In order to make use of the lower bound theorem of classical plasticity, two basic assumptions have to be made. Firstly, the material exhibits perfect plasticity, and obeys an associated flow rule without strain hardening or softening. Secondly, the body is assumed to undergo only small deformation at the limit load, and so the geometric description of the body at collapse remains unchanged. Both of these assumptions are reasonable in the case of unreinforced masonry shear walls. In the present paper, the yield surfaces of the intact brick units and of the head and bed joints are expressed separately. By using a Mohr–Coulomb approximation of the yield surfaces, the proposed numerical procedure computes a statically admissible stress field via linear programming and finite elements. The stress field is modelled using linear three-noded triangular elements and allowing statically admissible stress discontinuities at the edges of each triangle. By imposing equilibrium, yield criterion and stress boundary conditions, an expression of the collapse load is formed, which can be maximized subject to a large number of linear constraints on the nodal stresses. Because all the requirements are met for a statically admissible stress field, the solution obtained is a rigorous lower bound on the actual collapse load. The numerical solutions obtained from the lower bound formulation are compared with available experimental and finite element results from the literature. The lower bound approach developed in the present paper is shown to give good approximations to the ultimate collapse load for the two examples presented. 2010-04-27T06:54:16.529Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2840 In this paper, some practical aspects of the finite element implementation of critical state models are discussed. Improved automatic algorithms for stress integration and load and time stepping are presented. The implementation of two generalized critical state soil models, with one described first in this paper and the other recently published elsewhere, is discussed. The robustness and correctness of the proposed numerical algorithms are illustrated through both coupled and uncoupled analyses of geotechnical problems. 2010-04-27T06:33:17.033Z ]]>