The use of the node-based smoothed finite element method to estimate static and seismic bearing capacities of shallow strip footings

Abstract

The node-based smoothed finite element method (NS-FEM) is shortly presented for calculations of the static and seismic bearing capacities of shallow strip footings. A series of computations has been performed to assess variations in seismic bearing capacity factors with both horizontal and vertical seismic accelerations. Numerical results obtained agree very well with those using the slip-line method, revealing that the magnitude of the seismic bearing capacity is highly dependent upon the combinations of various directions of both components of the seismic acceleration. An upward vertical seismic acceleration reduces the seismic bearing capacity compared to the downward vertical seismic acceleration in calculations. In addition, particular emphasis is placed on a separate estimation of the effects of soil and superstructure inertia on each seismic bearing capacity component. While the effect of inertia forces arising in the soil on the seismic bearing capacity is non-trivial, and the superstructure inertia is the major contributor to reductions in the seismic bearing capacity. Both tables and charts are given for practical application to the seismic design of the foundations.