On the Design Process of Tensile Structures 15 Elastic redundancy re 2.06 Elastic redundancy re =2.33 Elastic redundancy re=2,68 Geometric redundancy r0.02 Geometric redundancy ra0.20 Geometric redundancy r0.33 Fig.17.Change of forces by shortening one link of 0,5%of its length equations for each element in a pretensioned structure and an additional geometric redundancy.The geometric redundancy of 3 says no influence of the geometric stiff- ness is required;the geometric redundancy lower than 3 describes the part of the geometric stiffness necessary for stabilisation and higher than 3 means the element is unstable and needed to be stabilized For the three cable nets the elastic and geometric redundancy can be analysed for the links and gives information to the influence of manufacturing errors,the possibility of pretensioning and the height of the tension forces related to the defor- mation.The change of the 0,5%of the length of one link causes in the net with the hexagonal meshes no changes in the forces,shown by the elastic redundancy close to zero.The opposite can be seen in the net with the triangle meshes,the change in the length causes in that element an increasing force. References 1.Gruindig L (1976)Die Berechnung von vorgespannten Seilnetzen und Hangenetzen unter Beruicksichtigung ihrer topologischen und physikalischen Eigenschaften und der Ausgleichsrechnung.1.SFB 64 Mitteilungen 34/1975, 2.Dissertation DGK Reihe C.Nr.216. 2.Singer P (1995)Die Berechnung von Minimalflachen,Seifenblasen,Membra- nen und Pneus aus geodatischer Sicht.Dissertation,Technische Universitat Stuttgart,Deutsche Geodatische Kommission-Reihe C,Heft Nr.448,Miinchen. 3.Bletzinger K-U (2002)Formfindung von leichen Flachentragwerken.in Baustatik-Baupraxis 8,Institut fuir Statik,TU Braunschweig. 4.Bellmann J (1998)Membrantragwerke und Seifenhaut Unterschiede in der Formfindung.Bauingenieur,3/98. 5.Lewis WJ,Lewis TS(1996)Application of Forminan and Dynamic Relaxation to the Form Finding of Minimal Surfaces.Journal of International Association of space and shell structures 37(3):165-186. 6.Barnes M(1999)Form Finding and Analysis of Tension Structures by Dynamic Relaxation.Int.Journal of Space Structures 14:89-104.On the Design Process of Tensile Structures 15 Fig. 17. Change of forces by shortening one link of 0,5% of its length equations for each element in a pretensioned structure and an additional geometric redundancy. The geometric redundancy of 3 says no influence of the geometric stiff- ness is required; the geometric redundancy lower than 3 describes the part of the geometric stiffness necessary for stabilisation and higher than 3 means the element is unstable and needed to be stabilized For the three cable nets the elastic and geometric redundancy can be analysed for the links and gives information to the influence of manufacturing errors, the possibility of pretensioning and the height of the tension forces related to the defor￾mation. The change of the 0,5% of the length of one link causes in the net with the hexagonal meshes no changes in the forces, shown by the elastic redundancy close to zero. The opposite can be seen in the net with the triangle meshes, the change in the length causes in that element an increasing force. References 1. Grundig L (1976) Die Berechnung von vorgespannten Seilnetzen und ¨ Hangenetzen unter Ber¨ ¨ ucksichtigung ihrer topologischen und physikalischen ¨ Eigenschaften und der Ausgleichsrechnung. 1. SFB 64 Mitteilungen 34/1975, 2. Dissertation DGK Reihe C, Nr. 216. 2. Singer P (1995) Die Berechnung von Minimalfl¨achen, Seifenblasen, Membra￾nen und Pneus aus geod¨atischer Sicht. Dissertation, Technische Universit¨ ¨ at Stuttgart, Deutsche Geod¨atische Kommission – Reihe C, Heft Nr. 448, M¨unchen. 3. Bletzinger K-U (2002) Formfindung von leichen Fl¨achentragwerken. in Baustatik-Baupraxis 8, Institut f¨ur Statik, TU Braunschweig. 4. Bellmann J (1998) Membrantragwerke und Seifenhaut Unterschiede in der Formfindung. Bauingenieur, 3/98. 5. Lewis WJ, Lewis TS (1996) Application of Forminan and Dynamic Relaxation to the Form Finding of Minimal Surfaces. Journal of International Association of space and shell structures 37(3):165–186. 6. Barnes M (1999) Form Finding and Analysis of Tension Structures by Dynamic Relaxation. Int. Journal of Space Structures 14:89–104. Elastic redundancy rE = 2.06 Elastic redundancy rE = 2,33 Elastic redundancy rE = 2,68 Geometric redundancy rG = 0,02 Geometric redundancy rG = 0,20 Geometric redundancy rG = 0,33