Experimental investigation on forming design methods of EFTE cushion

Abstract

ETFE cushion structure has been widely used as building roof and façade in lots kinds of civil buildings due to its advantages that mainly include transparent, lightweight, durability. There are mainly two design methods to determine the form of ETFE cushion. According to the model used for the analysis process of cutting, the two forming design methods consist of three-dimensional pattering method and flat patterning method. To investigate the forming design methods of ETFE cushion, two methods are presented which are the three-dimensional patterning method based on the zero-stress state and the flat patterning method based on nonlinearity of ETFE material. The physical states and mechanical models are defined for the two methods, respectively. On the basis of the theoretical analysis, experiments and numerical simulations on the two separate ETFE cushions are performed to obtain the shapes, stress distributions and the variations. It is found that, for the three-dimensional patterning model, the maximum difference of the shapes between experimental and numerical results is only 4 mm and the difference of the stress distributions is only 0.4 MPa. For the flat patterning model, a good agreement between the experimental and numerical results is obtained for the initial shape, and it is obtained that the stress decreases when the shape height and the ratio of rise to span increase due to the creep properties of ETFE materials. These findings have validated the proposed forming design methods, which are great importance for the application and development of ETFE cushion.