SEISMIC BEARING CAPACITY FACTORS OF SHALLOW STRIP FOOTINGS

In determining the bearing capacity of shallow strip footings under earthquake loading conditions, most seismic codes neglect the effect of the inertia of the soil mass underneath a footing. Seismic acceleration is considered to be acting on the structure only. In this Paper, the seismic bearing capacity factors (i.e. Nq, Nc and Nr), are determined by using the limit equilibrium technique of slope stability analysis with inclined slices. The analysis shows that the factor. Vq is dependent on the inertia of the surcharge load; the relationship between Nc and Vq given in the literature is found to be incorrect for inclined loads and the inertia of the soil mass certainly has an effect on Vy. Results of the analysis are shown in graphical forms as functions of the horizontal acceleration factor and of the angle of internal friction of the soil. The analysis does not include the effect of the excess pore water pressure generated by the earthquake. For small accelerations, smaller than 0·lg the effect of the i...