huangyhg

design of fabric membrane roofs
muttum,
i do not think i can answer all your questions but the following may be helpful...
the analysis of tensioned fabric structures is a non-linear problem. actually, the materials used are also highly non-linear, but fortunately the materials are approximately linear for the allowable stress range of most structural membranes.
scaled models using stretched fabric or soap films are often used to investigate the initial behavior, and the initial shape or form.
load analysis is done from a starting shape that is in equilibrium with the initial prestress. form finding is the process of determining this initial equilibrium shape, and finding this unique shape compatible with the given prestress usually requires a nonlinear computer analysis.
most companies that design and constructed these specialized structures (eg birdair) have in-house software that somewhat automates the form finding process. such programs use techniques such as non-linear stiffness analysis, dynamic relaxation, or force density to converge on the equilibrium shape.
it is a specialized subject area, and you are probably best to do a literature search on the topic. guru's like horst berger, frei otto and peter rice have written substantial works on this topic, including topics covering the art and architecture of these structures.
also the asce has a publication called "a practical introduction to tensioned fabric structures" that may prove useful to you.
hart.
muttum (visitor)5 feb 02 6:23
thank you very much for your response. i got some docs on membrane structures but they don't give much info about the design process. i'm studying a steel structure being attached with fabric membranes and stainless cables and trying to verify the reaction from membrane fittings and cables given by a fabricator. my problem is about the starting shape to do nonlinear fe analysis as you mentioned. will try to get more docs as suggested.
2 references
fabdes on cdrom- a design and educational resource for tensioned
fabric structures
dr peter kneen, consultant
engineering education development project
jakarta, indonesia
(a downloadable pdf, search in google)
dr peter kneen is the author of fabdes and was a professor at the university of new south wales, sydney, australia.
fabdes does have form finding capabilities, but it is written in fortran and the input and output is a bit cumbersome - not graphical input etc. his notes that are available on the web (as per ishvaaag post) are good and worth reading but peter no longer works on supporting fabdes, so you may get some good info, but you probably will not be able to get any additional support.
i recently recevied a sample copy of strand7 fea software(
thank you very much for all inputs. ingenuity. could you mail me the strand7 example? i had few experiences with strand7 in the past and would like to take a look how it looks like.

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