What percentage of reinforcement should be when creating the foundation

What is the percentage of reinforcement, why is it to take into account the reason for the construction

 Typically, the percentage of reinforcement is accepted no more than 3%, the minimum percentage is accepted 0, 3-0, 4%, which is most common in practice – 1-2%.

Design features of centrally compressed elements. The central compression occurs when the line of action of the longitudinal force coincides with the geometric axis of the element. Stags and columns, the upper zones of the farms during nodal load, individual grate elements, etc. work for central compression. D.