Alberto Pugnale

On the optimal design of glass grid shells with planar quadrilateral elements

This paper presents an optimization procedure for the solution of the planarity problem, a requirement of grid shells with four or more sides faces that need of having four adjacent nodes laying on a plane in order to use plane glass slabs as cladding elements. It can be satisfied by applying specific geometric rules in the grid generation phase but, when the architectural shape is already defined at the conceptual stage, an optimization procedure can yield to suitable configurations. A Relaxation method based on nodal planarity errors and an evolutionary population based Genetic Algorithm have been applied to set of benchmarks, in order to tune parameters and to obtain general information about the solution. the problem and their efficiency compared. The Relaxation method in general shows better efficiency in reaching optimal solutions, as an effect of the regularity of the target function. The Genetic Algorithm, on the other hand, performs a wider exploration of feasible solutions, generating unexpected sub-optimal configurations.

Integrating Form, Structure and Acoustics: A Computational Reinterpretation of Frei Otto's Design Method and Vision

In several of Frei Otto’s early membrane structures, acoustics was a rather relevant design aspect that could not be controlled through classical form-finding approaches based on physical models. Moreover, it is possible to add that, geometrically speaking, Frei Otto’s membranes could naturally perform acoustically, because of their anticlastic shape and the ability of the convex areas to scatter sound. In this paper, two of Frei Otto’s key projects are revisited and redesigned parametrically using mathematical optimisation: first, the Dance Pavilion that was conceived for the Federal Garden Exhibition in Cologne (1957); and, second, the large umbrellas that were built at the same venue in 1971. His architectural form of “necessity” represents the structural optimum, that is, a buildable technology, which can now be informed by other performance criteria, such as acoustics. This paper was inspired by the rock set designs of Mark Fisher and – in particular – by the retractable umbrellas that Frei Otto designed, in 1977, for the second leg of Pink Floyd’s “In the Flesh Tour”, which was also known as the “Animals Tour”.

Parametric Design and Construction Optimization of a Freeform Roof Structure

The pioneering works by Poleni, Rondelet and especially Gaudi, shows how some structural principles related to the field of shape-resistant structures has been well-known for centuries. The design of structural shape has been approached differently; the more analytical way of engineering, such as the works of Dyckeroff and Widmann or the intuitive approach of engineering referring to the works of Torroja. The focus for the new structures was lightweight, large spans, functionality, efficiency and economy. This brought new developments of form-findings structures, i.e. a set of tools and strategies to find the form of ’structural minimum’ - in shells where the surface is mainly stressed in the plane with compression, tension and shear. The research started with the development of experimental tools, or physical models, reaching a high point with the work of Heinz Isler [2]. However, this prosperous period has been concluded in about 20 years, since the rigid generative rules of shape-resistant structures brought to the rapid exploration of the complete family of potential shapes of shells during the 60ies.