Bearing capacity factor Ny for a rough conical footing

The bearing capacity factor Ny is computed for a rough conical footing placed over horizontal ground surface. The axisymmetric lower bound limit analysis formulation, in combination with finite elements and linear programming, proposed recently by the authors is used in this study. The variation of Ny with cone apex angle (B), in a range of 30o-180o, is obtained for different values of ?; where ? is soil friction angle. For ? < 30o, the magnitude of Ny is found to decrease continuously with an increase in B from 30o to 180o. On the other hand, for ? > 30o, the minimum magnitude of Ny is found to occur generally between B = 120o and B = 150o. In all the cases, it is noticed that the magnitude of Ny becomes maximum for B = 30o. For a given diameter of the cone, the area of the plastic zone reduces generally with an increase in B. The obtained values of Ny are found to compare quite well with those available in literature.