New Method for Computing Bearing Capacity of Block Foundations in Transmission Lines-II

Reference 1 dealt with the computation of block foundations in different kinds of soils and the equations presented therein give the values of the yield limit moments. The additional tests which have been carried out since then have given further support to the computation theories. The equations have been further extended and are now also applicable when the moment bends over a corner of the foundation. It is not unusual for the foundation to be tilted at an oblique angle to the sides. Through the extension of the equations in the present paper, they have now a considerably greater range of application than in reference 1. The question of permissible moment has been treated for the different soils. Owing to certain probable errors of the soil characteristics, there will always be an error, of varying extent, in the computation of the foundation. The factor of safety has been chosen so high that this error will always lie between calculated and permissible moments. Greater moment than the yield limit can be permitted for a foundation in cohesion soil if the tilting moments are of short duration, e.g., if they come from wind loads, which is the case with transmission lines. Because the equations are based on soil characteristics that can be determined by simple soil investigations, and owing to the way of determining the permissible moment described in this paper, the calculation will be more accurate than in earlier methods.