AbstractsEngineering

This report describes the development of a multifunctional building and the research that supports the design. The question was “what are the characteristics of a multifunctional exhibition hall of which the structural design is integrated with the variable acoustical design and of which the acoustic properties are used as decisive factors in the visual appearance of the design?” Combining acoustical shapes with structural design can lead to intriguing forms. Using computer analysis, literature studies and case-studies a concept design was developed. As a foundation for the design the existing exhibition complex WTC expo Leeuwarden was used. The new hall replaces an existing hall and thus it has to be an addition to the functionality of the building, rather than a replacement. This has been done by not creating a hall only functional as an exhibition hall but as a concert (amplified music) hall, acoustical music hall and speech hall as well. Especially the acoustical music hall should meet very specific acoustical properties. The other functions have different acoustical properties. The exhibition hall requires an empty floor plan, which results in a challenging structural design scope as well. To minimize the amount of materials needed for the structure the aim is to integrate the acoustical shape and materialisation with the structural design. Literature study explains the relation between sound waves, frequencies, reflections and how they contribute to the experience of the audience in a concert hall or auditorium. Important elements for the experience of the receiver of the sound are envelopment, reverberation, clarity and loudness. Envelopment depends on the sound direction as perceived by the receiver. A larger variety of sound directions results in a better envelopment, which is desirable for music related functions. Reverberation time, clarity and loudness can analysed objectively. The current shapes of concert halls are derived from optimization of either view or envelopment, but not both. The rectangular and hexagonal shaped concert halls are the most successful in combining a good view and envelopment. Folding techniques have been inventoried. By folding the roof or wall, a surface is created which can diffuse the lateral sound reflections and create a better envelopment. The angle of the folds and direction of the surfaces strongly influences the envelopment. They function best when the folding lines are parallel to the main sound direction. The exhibition building in Turin, designed by Nervi, shows how a structure with a large span can be reached with a minimum amount of material. Nervi also designed the UNESCO conference building in Paris. This building is an example how structure can be combined with the acoustical shape of a hall. While these projects where used as an inspiration, ‘de Spiegel’ in Zwolle is an example how moving elements and changing volumes can change the reverberation time and clarity of a hall. Based on the literature study and case studies, a concept was developed where a…