  Truss structures composed of members that work exclusively in tension or in
compression appear in several problems of science and engineering, e.g., in the
study of the resisting mechanisms of masonry structures, as well as in the
design of spider web-inspired web structures. This work generalizes previous
results on the existence of cable webs that are able to support assigned sets
of nodal forces under tension. We extend such a problem to the limit analysis
of compression-only 'strut nets' subjected to fixed and variable nodal loads.
These systems provide discrete element models of masonry bodies, which lie
inside the polygon/polyhedron with vertices at the points of application of the
given forces ('underlying masonry structures'). It is assumed that fixed nodal
forces are combined with variable forces growing proportionally to a scalar
multiplier (load multiplier), and that the supporting strut net is subjected to
kinematic constraints at given nodal positions.
