In the design of circular reinforced concrete footings subject to axial load and flexure in a direction are presented different pressures throughout contact surface, which are exerted by the soil. In this paper, we develop a mathematical model to take into account the real pressure of the ground acting on the contact surface of the circular footing of shear force by penetration (shear force bidirectional), when applying the load that must support the said member of structure. The traditional model takes into account the maximum pressure of the ground to design the footings and is considered uniform at all the points of contact, i.e., that the entire surface has the same pressure. The proposed model takes into account the actual pressures, i.e., considers the pressures generated in the entire contact surface of the footing and generally are different, with a linear variation in the contact surface. Also, develops a comparison between the two models as shown in the result tables. According to the data obtained, it is shown that the traditional model is larger than the model proposed. Therefore, normal practice to use the traditional model will not be a recommended solution. When is best to use the proposed model, since it is more economic and also more attached to real conditions.

circular footings, differential element, real pressures, contact area, resultant force, shear force by penetration, shear force bidirectional.