Architectural and Structural Development of Plate Tensegrity

Plate tensegrity is a structural principle combining the approach to the play of forces seen in tensegrity with plate and shear-plate action of surface elements and facetted shells. The origin of the concept and the potential development as a structural element system describes a step-by-step modification of the original definitions of tensegrity towards a hybrid structure with cable-stayed plates. The work deals with development of the combination of structural elegance and efficiency and architectural utility and quality. The structural principle has not yet been applied in practice, but the performance of different assemblies are being further analysed from structural and architectural points of view. There are a number of features of plate tensegrity that can be utilised both structurally and architecturally. Stability of plate shells has been treated by e.g. Almegaard and Vanggaard. Pure shells tend to be sensitive to cuts in their edge zones and loose in stability and there are polyhedral types showing the same behaviour if certain facets are removed, as described by e.g. Wester. The cable network in plate tensegrity may be utilised to allow removal of elements inside as well as at the edge of an assembly. The cables also make possible different geometries of the assemblies, by variations in lengths i.e. intermediate distances between the strut ends in the structure. The first modelling of plate tensegrity was focused on straight assemblies of a single unit type with a square plate shape, considering production rationality and economy. Analyses of curved assemblies are now in progress, however, and triangular plate shapes to open up for other geometries are aimed at and planned. The geometrical relations in the structure are of importance for both structural performance and architectural usability. Comparisons with an existing equestrian hall have been initiated and are to be continued, eventually aiming for a stock example of a hall of medium size. In the case of the structural performance, geometries, shapes, cuts and edge stabilisation are of interest. In case of the architectural usability the utilisation of the structural potential as well as relations between the structural principle, its supporting structure and the created space need to be worked through. The paper describes further development of structural principles and architectural use.