The first sketches to capture an idea are always free of any thoughts of loads or compulsory form finding processes. At this stage, the designer is as free to draw a curved line as to outline a box. It is crucial not to focus attention on loads or computational modelling. It’s only the second step that involves complementary design features. With respect to form finding beyond the initial sketch, tensile constructions follow completely different principles to other structures. The main difference lies in the self-regulation mechanisms of tensile membrane constructions.
The initial decision for an overall form implies reactions from the material that must not be undermined by contradictory features. Furthermore, the geometry of a tensioned membrane system cannot be precisely defined before analysis. Nonetheless, permanent tensile membrane structures are designed to resist the same basic loading criteria as conventional buildings. Imposed minimum live loads and wind pressures are derived from the requirements of the local building code or the governing model code.
As part of a preliminary design process, a provisional load analysis will give typical load directions. One output of the so derived computer model is figures of the loads to be transferred to the supporting structure. The architect will usually already cooperate with an engineer at this early stage in the design process. A prompt cooperation not only makes sense concerning the handling of modelling software, but also simplifies the integration of different parts of the structure – often there is a combination of tensile and non-tensile architecture. The architect and engineer together can make the best of this combination.