Air-supported membrane structures maintain their shape and resist external loads by maintaining internal air pressure. Meanwhile, the internal pressure also acts as a load on the structure and should be considered along with other loads. The internal pressure is a variable parameter in structural design, which can be pressurized or depressurized according to the external loads to adjust the stiffness and strength of the structure.
Internal working pressure refers to the maximum pressure that can be used by the operator when the structure is subjected to adverse external conditions, such as the indentation of the membrane due to water (snow) accumulation. Determining the maximum working internal pressure should consider various factors, including the design strength of the material and the type of external loads. The internal pressure of an air-supported membrane structure should ensure that the structure meets the requirements for strength and stability under various loads.
Internal working pressure under small load refers to the small pressure value required to maintain structural stability under normal climate and operating conditions. When the dead load is distributed over a certain influence area, the internal working pressure under small load should exceed the maximum value of the dead load per unit area.
Normal operating pressure is a pressure range determined by designers. Under normal operating pressure, the structure can maintain stability under common loads. The operating pressure should vary between the minimum and maximum working pressures based on usage and flow conditions. In public gathering places, to ensure comfort, the wind speed at entry and exit points and the pressure exerted on the doors should be appropriately reduced, with the working pressure not exceeding 287Pa. For spaces primarily used for storage, the working pressure can be higher during vehicle entry and exit to ensure structural stability.
When designing, it is essential to reasonably determine the membrane structure's large working internal pressure, small working internal pressure, and normal working internal pressure. The large working internal pressure should ensure that the structure does not undergo excessive deformation under adverse external environmental conditions. The small working internal pressure should guarantee the stability of the structure under normal climatic conditions and normal use, with a value not less than 200Pa. The normal working internal pressure should ensure the stability of the structure under common loads and maintain indoor comfort.
The anchoring system should be selected based on the nature of the structure (temporary, semi-permanent, or permanent). The foundation anchoring system is prone to both short-term and long-term creep under tension or buoyancy, which can lead to uncertain additional loads between the upper structural system and the foundation anchoring system. All anchoring components of the air-supported membrane structure should be carefully designed.
The design of the membrane structure's anchoring system should comply with relevant structural design standards and ensure that the membrane, tendons, or other reinforcing elements are securely and reliably anchored to the ground or other structural components.