Numerical implementation of a yield vertex non-coaxial model

This paper ascertains the reasons for the numerical non-convergence problem when the yield vertex non-coaxial model is implemented in the finite element analysis to predict the behaviour of a complicated geotechnical engineering problem, shallow foundation behaviour. It is found that a large non-coaxial influence at the start of elastoplastic loading, which causes the predominance of non-coaxial plastic strain rate over the coaxial plastic strain rate in stress-strain responses, is the reason for the numerical problem. The original yield vertex non-coaxial model is modified to overcome the numerical problem. It is shown that the modified non-coaxial model retains the functions of the original non-coaxial model. Meanwhile, it overcomes the non-convergence problem when a larger non-coaxial influence is considered.