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Integrating Form, Structure And Acoustics: A Computational Reinterpretation Of Frei Otto's Design Method And Vision
Abstract
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.
The work described in this paper could show a possible way of expanding Frei Otto’s two-step design method, which was based on the sequential use of a form-finding model first – to literally “find” structural form – and then a technological model – to study the tectonic aspects of the structure and endow it with materiality.
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”.
... Considering other criteria for the design of the shell structures rather than structural performance in the literature, this is not adequately reflected in the research. Pugnale [29] tried to assess the acoustic and structural performances of two previously wellknown shells that Frei Otto discovered using the traditional hanging model method. Results indicated that taking acoustic as an objective function changes the best (fitness) solution that were provided by the hanging model since it generates the form based on the structural behavior. ...
While the hanging model and physical prototyping are reliable methods for form-finding continuous lightweight shell structures, they cannot explore various design possibilities and consider multiple criteria in the design. This research aims to employ metaheuristic algorithms as a search tool for simultaneous form-finding (form exploration) and optimization, known as computational morphogenesis. This workflow consists of a parametric model and metaheuristic algorithms, which were implemented through costume Python codes. To evaluate the workflow, a double-curvature footbridge was defined, and the forms that GA found were in line with the anticipation. The GA found a better solution (0.04022) than the SA (0.064) by considering elastic energy change. In case study II, the optimal form of a continuous lightweight shell was explored by utilizing GA, PSO, SA, and the hybrid algorithm of GAPSO. The GA improved the fitness solution by 35% in the second run, while PSO showed similar results, and the hybrid GAPSO algorithm did not yield better results. The results show that the optimum result based on different algorithms was not significantly different. Nevertheless, hyperparameters considerably affected finding the global minimum. Moreover, NSGA-II was utilized, which let the designer trade-off between alternatives while considering other criteria.
... This acoustic shell, also known as "ReS", was first conceived in 2012 to be assembled and disassembled from wooden components and its design has then been improved and refined on a yearly basis [11], 17]. Aeolus was also used by Pugnale [18] in 2018 to study the acoustic performance of some of Frei Otto's most known tensile structures. In teaching and learning, Aeolus has been used for the past four years as the parametric acoustic analysis software in an architecture master's design studio at The University of Melbourne: the focus has been the acoustic design and optimisation of a music concert hall and school. ...
The design of music venues, such as concert halls and open-air concert stages, requires an integrated approach in which the acoustic response of the space being created is evaluated at every stage of the process to inform its formal development and associated performance. Various software exists to assess acoustic performance: Odeon is considered by many as the industry standard standalone software for detailed and accurate acoustic analyses, whereas Pachyderm is a plugin for Grasshopper (Rhinoceros 3D), which provides architects and engineers with more rapid feedback on preliminary design ideas because of its integration with a parametric modelling environment. Although an experienced acoustic designer could rapidly learn to use any of these programs, their usefulness during conceptual design or teaching activities is limited by the computational power and time required to get acoustic performance results. In these instances, testing time is more valuable than accuracy.
This paper introduces Aeolus, an acoustic modelling plugin for Grasshopper. Unlike other similar Grasshopper plugins, Aeolus allows users to control the simulation accuracy and can therefore be used to rapidly test the performance of design ideas. Aeolus can also easily be interfaced with various Grasshopper optimisation plugins. Aeolus v0.1 was publicly released on 7 March 2023, and will be the focus of a Masterclass offered at the IASS Symposium 2023 in Melbourne, Australia.
... It is worth recalling that minimal surfaces generated from a single closed frame, either using soap bubbles or fabric sheets, are always anticlastic saddle shapes that closely resemble the geometry of the hyperbolic paraboloid. Therefore, it is easy to draw formal parallelisms between Candela's restaurant at Xochimilco and the 1957 Dance Pavilion designed by Otto in Cologne for the Federal Garden Exhibition (Fig. 4.9) (Pugnale 2018). Although the former is a concrete shell conceived to use hypars, and the latter is a tensile structure, hence a minimal surface, both designs have wavy façades with large openings that result from two different structural-form generation methods. ...
This book reviews Dante Bini’s inventions and designs, focusing on his form-resistant Binishell and other pneumatic construction systems. Dante Bini’s double profile of architect and builder underpins the narrative of the entire book. It is used to analyse the evolution of the early reinforced-concrete Binishell patent into a variety of automated construction systems based on the use of air. Dante Bini has always been quite proactive in promoting his work and disseminating the results of his experimentations and achievements via journal articles, conference presentations and public talks; promotional brochures in multiple languages were also prepared to export and license his patents in various countries, from Italy to the Americas and Australia. Despite this, a rigorous study of Dante Bini’s work is still unavailable, and the relevance of this figure to contemporary architecture has yet to be discussed comprehensively. This book fills in this gap and arrives at the right time: during the last two decades, there has been an exponential interest in shell and spatial structures, particularly concerning the use of complex geometries and innovative construction techniques.
This book will be of interest to academics in architectural design, theory and construction history, and practitioners and students interested in expanding their knowledge in the design and construction of shell and spatial structures.
Designing efficient and sustainable buildings is an essential focus in architecture and engineering, often tackled through various different optimization methods. However, the complexities of the design process and its multiple criteria pose challenges. In this sense, multi-objective optimization has emerged as a valuable tool for integrating these diverse requirements. This study synthesizes research on multi-objective optimization in building design, identifying key characteristics, and evaluating the correlation between its variables and objectives. A literature review was conducted to assess the main studies about this type of optimization, determining the most common variables and objectives and their combinations. The results show that although multiple objectives exist, they often belong to the same field. The findings reveal that volume shape and structural shape are standard variables in optimization, linking architecture, structure, and environmental impact. Overall, the review showed the opportunities for exploring multi-objective optimization to integrate these three fields.
This study presents the optimized shape and thickness of thin continuous concrete shell structures, minimizing their weight, deflection, and elastic energy change while meeting performance requirements and minimizing material usage. Unlike previous studies that focused on single-objective optimization, this research focuses on multi-objective optimization by considering three objective functions. This combination of objective functions has not been reflected in previous research, distinguishing this study. The computational design workflow incorporates a parametric model, multiple components for measuring objective functions in the grasshopper of Rhino, and a metaheuristic algorithm, the non-dominated sorting multi-objective genetic algorithm (NSGA-II), as the search tool, which was coded in Python. This workflow allows us to perform form-finding and optimization simultaneously. To demonstrate the effectiveness of this metaheuristic algorithm in structural optimization, we applied it in a case study of a well-known shell designed using the physical prototyping hanging model technique. Interpretations of samples of optimized results indicate that although solution-1 weighs nearly the same as solution-2, it has less deflection and strain energy. Solution-3, with a three-fold mass, has significantly less deflection and strain energy than solution1 and solution2, with deflection reductions of over 50% and 17%, respectively. Solution-3 and Solution-4 show better deflection and strain energy performance. Furthermore, A comparison of the MOO results with the Isler shell revealed that this method found a solution with less weight and deflection while being stiffer, confirming its practicality. The study found that MOO is a reliable method for form-finding and optimization, generating accurate and reasonable resul
This paper presents a deterministic method to design acoustic chambers for outdoor performances, and emphasises the benefits of a computational morphogenetic approach to the problem. It represents the newest outcome of a research program, conducted by ReS-Team and sponsored by VPM, on the development of the acoustic chamber ReS. The research work is based on the interaction between two different topics – Computational Morphogenesis and Acoustics-which proceed on independent but parallel paths. As a computational tool for any Python ®-based environment, it aims to fill the gap between the architectural and acoustic design. By means of geometrical acoustics theory, descriptive geometry and genetic algorithms, the acoustic performance of a given topology is optimised according to defined acoustical parameters. The awareness of possible variations in the acoustic configuration is also increased. Applications are meant to predict the acoustic behaviour within any semi-reverberant field of an acoustic environment.
Today architectural design processes are more and more influenced by parametric methods. As
these allow for a multiplicity of alternatives, the design process can be enriched by computational
optimization. Extensive research has shown the efficiency of optimization in engineering and design
disciplines. Though, optimization is hereby rather a technical than a design task; it is limited to
different autonomous specialist areas and does not enable a comprehensive approach. Advanced
optimization methods facilitate the generation of complex systems, but these procedures are directed
and do not provide turnoffs, multiple solutions, or altering circumstances.
These, however, are things that are essential for architectural design processes, which mostly
do not have clearly defined starting and end points. This practice subdivides the workflow into two
independent and recurring tasks: the generation of a parametric model followed by optimization of
its driving parameters. The result is then assessed with respect to its actual qualities. The design
either is kept, or modifications on the parametric model, its auxiliary conditions, and parameters are
made and the optimization process starts again from scratch.
The aim of this work is the development of basic structures for a flexible generation and optimization
framework for practical use in the sense of a continuously accompanying design explorer,
in which parameterization is adaptable and objective functions are changeable at any time during the
design process. The user is supported in his/her understanding of correlations by identifying a multiplicity
of optimal solutions utilizing state-of-the-art multi-objective search algorithms within the core
of the framework. Considering the tool as an interactive design aid, an intuitive interface allowing
for extensive manual guidance and verification of the search process is featured. User-selection of
prefered solutions support man-machine-dialogue and incorporation of non- or not-yet quantifiable
measures. A reusable search history aids examination of design alternatives and the redefinition of
constraints maintaining the continuity of the search process and traceability of results in the sense of
a rational design verification.
Within this work it is not planned to focus on specific optimization targets, but to build an open
framework to allow for all kinds of objective functions and in particular the mediation between conflicting
targets. A basic platform should be established, applicable in real-world modes of operation
that satisfies increasingly complex correlations of modern architecture’s requirements as a powerful
extension of classical design methods.
Membranes used for building materials have a certain degree of acoustic permeability, which has been disregarded in general membrane-vibration theory, and may cause serious effects especially on the acoustic properties. In this study, a theory for sound absorption of, and sound transmission through, a single permeable membrane is developed. Subsequently, sound absorption of structures composed of air layers, absorptive layers, and the facings of permeable membranes is investigated theoretically, and discussed in comparison with the experimental data measured by using the reverberation-room method. The results are in fairly good agreement; thus the present theory should give an effective tool for prediction of the acoustic properties of this type of membrane structure. (C) 1996 Acoustical Society of America.
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