Fig. (13) Examples of singular stress fields. Singular (right) and regular (left) statically admissible
stress fields, corresponding to a concentrated load applied at a point on the boundary:
(a). Singular stress inside a reinforced concrete beam: (b), (c). Uniaxial stresses emanate form
the upper boundary, concentrated compressive stresses have support on the curved lines (represented
by a double line in the pictures), tensile concentrated stresses have support on the
solid straight line at the bottom (the rebar). Below the curved lines the stress is zero.