The design of a D-region includes the following steps:

  1. Define and isolate each region.
  2. Determine the resultant forces acting on each D-region boundary.
  3. Select a truss model to transfer the resultant forces across the D-region. The axes of the struts and ties should coincide, approximately, with the compression and tension fields.
  4. Determine the effective widths of the struts and nodal zones based on the concrete and steel strengths and the truss model chosen.