Abstract:
Starting from the reinterpretation of the natural forms that recurs in the consolidated
shapes of historical buildings, the research proposes the umbrella vault as isolated selfsupporting
cover. The research outcome, defined with the term "structural tree", can be
considered as an extreme experimentation of the cooperation possibilities between natural
stone and steel reinforcement.
The idea arises from the observation of fan vaults in which appears an isolated support:
its static behaviour works, of course, because of the presence of an opposite structural portion.
In this case, on the contrary, there are no lateral supports but it arises as a self-referential
element, while the task of restoring the structural balance is left to the upper reinforcement
that allows a free composition of the "tree" without static constraints. The study is based on a
formal research that combines the possibility to create serial and repeatable compositions with
the achievement of an ideal static equilibrium configuration of the stone structure that
considers the collaboration between the voussoirs and the upper reinforcement.
The steel structure is not assumed as a pre-tensioned reinforcement, like in the other
prototypes, but as a passive reinforcement to recreate the compression condition of the arch,
usually generated by the opposing forces belonging to the two symmetrical halves.
