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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 89
Edited by: M. Papadrakakis and B.H.V. Topping
Paper 190

A Study of Foundations in Low Bearing Capacity Soil Using a Hyperbolic Paraboloid Shell

C.J. Martins1, O.S. Figueiredo1, R.A.F. Peixoto1 and L.A. Martins2

1Department of Civil Engineering, Federal Centre of Technical Education - CEFET, Belo Horizonte, Brazil
2Geological Service of Brazil - CPRM, Belo Horizonte, Brazil

Full Bibliographic Reference for this paper
C.J. Martins, O.S. Figueiredo, R.A.F. Peixoto, L.A. Martins, "A Study of Foundations in Low Bearing Capacity Soil Using a Hyperbolic Paraboloid Shell", in M. Papadrakakis, B.H.V. Topping, (Editors), "Proceedings of the Sixth International Conference on Engineering Computational Technology", Civil-Comp Press, Stirlingshire, UK, Paper 190, 2008. doi:10.4203/ccp.89.190
Keywords: non-linear analyses, constructive systems, finite elements methods, shell foundation, soil-structure iteration, parallel computing.

Engineering's foundation consists of a science as old as the art of construction, and no doubt we can say that this activity is present in all buildings developed by man [1]. Among the many structural elements used for the construction of foundations, the floor foundation is a flat structure that has many advantages when correctly specified and implemented. Overall, floor foundations are massive slabs that support and distribute, in a uniform way, the loads of buildings to ground. Given its simplicity of execution and excellent geotechnical behaviour, has been widely used in both residential as industrial structures [2].

To resist the loads from the superstructure acting perpendicular to the plan, internal forces of bending and shear develop in a flat foundation. In another way, in shell foundations (such as the hypar shells) internal forces due superstructure loads provide only internal forces in the plan, mainly in compression and in-plane shear forces [3]. This difference in behaviour implies a structural optimization in the design of shell foundations, since the material is subject mainly to internal forces of normal compression. The economy of material becomes more evident when such elements of the foundation are made of structural concrete, whose high performance under the action of internal forces of compression provide a great reduction in consumption of material. Obvious economic benefits reached from the use of shallow foundations in the form of shells are proven in several reports of applications in various parts of the world [2].

This objective for this work is to undertake a technical and economic analysis of the paraboloid hyperbolic shell foundation (hypar), made from reinforced structural concrete, as a solution for the shallow building foundation placed in a soil with low bearing capacity. The paper describes aspects of the structural and geotechnical behaviour of this shell foundation and a non-linear numerical analyses using a parallel finite element (FEM) code is described. From the results obtained through the numerical analyses and design, it will be demonstrate the technical and economic advantages of adopting of hypar shells to replace the usual solutions in shallow flat foundations. The validation of the work will be shown through a study of a set of residential building of three floors constructed in a soil with low ground bearing capacity, were about 50% of reduction in cost was achieved.

J.E. Bowles, "Foundation Analysis and Design", 5 ed., McGraw-Hill, 1996.
N.P. Kurian, "Shell Foundations - Geometry, analysis, design and construction", Alpha Science International Ltda, 2006.
W. Flugge, "Stresses in Fhells", New York, Springer-Verlag, 1973.

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