Inflatable structures or pneumatic structures are air-supported structures and find application in a variety of new engineering projects. By these structures the gas gives shape and strength to the structure in such a way that with larger volumes and higher pressures larger spans can be abridged. Their architectonic flexibility and the search for better structural efficiency are strong favorable arguments to the use of this kind of structure. Furthermore, inflatable structures can be erected or dismantled quickly, are light, portable and materially inexpensive. Also, some characteristics such as the utilization of natural lighting and ventilation and its possibility of reuse contribute to the pursuit of sustainable development. In this work the influence of the pressure-volume coupling on structure behavior is studied. A membrane formulation with deformation-dependent forces was implemented in a finite element model to take into account the influence of gas volume variation, with corresponding change in pressure for enclosed gas on the stiffness of membrane structures. An analytical solution of inflatable membranes was developed for the validation of the numerical results. Comparisons are carried out on a clamped circular membrane inflated by a uniform pressure.
