Examination on ultimate bearing capacity of footing by regid plastic finite element analysis

Abstract

In designing superstructure of buildings, it is important to estimate the ultimate bearing capacity of the building foundation. The ultimate bearing capacity formula of foundation is specified in the guideline published by Architectural Institute of Japan for design of building foundation. The rigid plastic finite element method was developed by Tamura to estimate the ultimate bearing capacity of footing. The characteristic of this method is to employ few numerical parameters. It does not use the Poisson's and the elastic modulus since it deals with the limit state directly by disregarding the deformation of building and ground. The rigid plastic constitutive equation proposed by Ohtsuka, which is displayed by the relationship between stress and strain rate, is employed in this paper. The strength parameters as cohesion, c and friction angle, φ are only employed. By performing a series of rigid plastic finite element analyses, the comparison of ultimate bearing capacity between the formula by Architectural Institute of Japan and the simulation results was conducted. Finally, the case study applied to the practical design was exhibited to show the applicability of numerical method to practice. In conclusion, it is clearly shown that the ultimate bearing formula is highly rational and the rigid plastic finite element method is effective to assess the ultimate bearing capacity of foundation.