| Summary |
Most of the structural forms in which ETFE film is used are the cushion type (pneumatic membrane structures) and tension type (tensile membrane structures), which are generally accepted to be the most efficient forms. For the tension type, the structures are pulled outward from the exterior to introduce membrane tension. And such structures offer the advantage of a natural shape formed by tensile stress and eliminate the need for blast air. Recently, the number of tension type structures is increasing. But, there are problems of creep and relaxation of ETFE films under long-term stresses. In previous works, the authors proposed a method for stretching the film into the plastic region during initial tensioning as a way to increase its strength, and demonstrate its effectiveness. To apply a stretching method in tension type structures, it will be necessary to introduce the initial stress and to generate a cutting pattern. In this paper, we investigate a possibility of stretching method in study models for various shapes. And then we examine its effectiveness by applying stretching method for membrane structures of tension type using ETFE films. |