In book: La bellezza per il rospo (Beauty according to the toad) (pp.221-222), Publisher: CLEAN Edizioni, Editors: Roberta Amirante, Carmine Piscopo, Paola Scala. Born in the world of mathematics to define all those “equations that express a set of quantities as explicit functions of a number of independent variables, known...

[More]*In book: "AAD Algorithms-Aided Design. Parametric strategies using grasshopper", (pp.352-359). Publisher: Le Penseur. Editor: Arturo Tedeschi.*

In architecture and structural engineering, ‘form-finding’ identifies the process of designing optimal structural shapes by using experimental tools and strategies, i.e. physical models, to simulate a specific mechanical behaviour.

The reverse hanging method is the oldest and probably most diffused form-finding technique for arches, vaults and shells – a physical model, made with elastic cables or membranes with no rotational stiffness, is first subject to gravitational forces to obtain a structural state of pure tension; such a form, which is called “funicular”, is then inverted to identify the mechanical compression-only situation.

This principle was first mentioned in a publication by Robert Hooke in 1675 . With a Latin anagram, only solved in 1701, he proposed to reverse the curve which was generated by a hanging chain, under self-weight and supported only at its ends, in order to define the optimal structural form of an arch. Such a curve is called “catenary” when the chain presents a constant distribution of weight . Initially confused with a parabola by Galileo Galilei, the catenary was then mathematically described by David Gregory in 1697.

[Less]