The development of tensioned fabric membranes has gone from the use of early stocking models and
'soap bubble' tests to the current use of multi programme software suites. Special non linear techniques are necessary for the structural analysis of tension structures, since membranes undergo large shape changes under varying load conditions and fabric materials exhibit complex stress-strain response. Finite element techniques can be used to solve these non-linear problems. FEA or finite element analysis breaks down the surface into finite elements or areas and analyses the
reaction effects and inter relationships of the elements. The main processes that generally need to be undertaken are as follows;
Simulated application of loads
Even with a rectilinear building it is difficult to asses the loads that may be imposed due to the variables of weather and in particular wind, which can exhibit unpredictable eddies and turbulence. When the force calculation is made more difficult due to the three dimensional form of a membrane there
are only three ways to assess the potential forces. One is to apply an overall pressure co-efficient (uniform load) which makes allowance for most conditions. While factors of safety are a vital part of engineering, over engineering can be detrimental to a project and not just on the grounds of cost. We use software applications which break down the surface of the membrane, sector by sector and apply a simulated load determined by direction of force and angle of approach. This provides a more
accurate method of determining potential force.
Validation of fabric properties
To provide accurate analysis of membrane structures, it is necessary to accurately asses the performance characteristics of the engineering fabric chosen, within the software. Once the chosen fabric exhibits the same performance characteristics in software as the physical tests, analysis can begin.
Finite element analysis
Typical membrane structures defy
classical analysis. Modern engineers use sophisticated software tools to generate virtual models which can represent the real world project. Every part of the virtual model can have properties simulated to represent forces and structural components in software. The model can then have surface pressures defined from projected wind and snow patterns as above and assigned. The analysis provides output forces and geometry. The output forces are used in the design of supports. | 
