Surface Fitting Approach for Tensile Membranes Design

The aim of this paper is to introduce a method for the conceptual design of membrane structures. Actually, there is a lack of computer based tools for the people involved in these first stages of the design process, in which the shape of the membrane is being defined. Not many parameters are needed at this stage for the designer. An easy graphic interface is needed, in which the designer had the possibility of varying in real time the shape of the membrane, and the environment around it, to achieve the desired shapes. A hybrid algorithm, based on a structural analysis and a surface fitting approach has been carried out to meet all the requirements. 1 Tensile membranes design process, from conception to realization This paper deals with the design of membrane structures. In this section, a description of the tensile membranes design process will be shown, from the preliminary sketches to the realization of the structure. As example, Figure 1 shows the initial sketch of a membrane structure, and a picture of the finished structure. Many tasks need to be completed to achieve the final structure. Figure 1. Tensile Membrane. San Sebastián. Spain. From conception to realization. Architects and Engineers are involved in the study of tensile membranes. It is widely know that architects are focused on the geometric shape of the membrane, while engineers are concerned with the internal stress distribution of the membrane. Both approaches are directly related, since the geometric shape of the membrane depends on the given initial pre-stress of the membrane. In Figure 2, a diagram with the tensile membrane design process is shown. Architects and Engineers have to work together, to meet the proposed requirements. The initial steps of the process are defined by the architect or the designer. At these stages, the initial ideas and sketches are drawn, to comply with the shape and space requirements. Many objects and volumes are located into the same space, and different iterations are needed until the desired layout and shape is achieved. These preliminary steps are really the most important stages of the process, because the initial conditions are being defined, and will be the base for the next stages. Once the project has started, a change in these initial specifications could result in the change of the whole project. Formfinding is a common technique used to obtain the initial shape of a structure membrane. There are different computer tools based on this technique, which help the designer to obtain the desired shape. Although the use of this kind of tools is indicated for the designers, the majority of the applications need to be used by advanced users, and many task need to be completed to achieve the final shape. IASS 2004 SYMPOSIUM MONTPELLIER