How to ensure the uniform distribution of pretension in tensioned membrane structures?

To ensure uniform pretension distribution in a tensioned membrane structure, precise initial design, graded tensioning operations, and regular maintenance are crucial. Specifically, this can be achieved through the following steps:

I. Initial Design Stage:
* **Pretension Setting:** Based on the membrane material type (e.g., PTFE membrane) and project requirements, set the warp and weft pretension values ​​(e.g., 200 kg/m) to ensure the membrane material does not loosen under normal use.
* **Morphological Analysis:** Prioritize finding the smallest surface with uniform stress. If this does not exist, select a surface with non-uniform stress but self-balancing properties.

II. Tensioning Operation Stage:
* **Graded Tensioning:** Use tools such as wire rope tensioners to tension the membrane in stages along the perimeter or stabilizing cables, ensuring uniform force on each clamp.
* **Force Application Point Selection:** Distribute force evenly to the perimeter through the force application point, avoiding dead zones; reduce force values ​​in high-altitude or confined areas.
* **Displacement Margin:** Allow for appropriate displacement margins to facilitate pretension adjustment and eliminate structural errors.

III. Maintenance and Adjustment Phase

Secondary Tensioning: After 1-2 years of normal use, secondary tensioning is required to compensate for stress loss in the membrane material.

Force Value Testing: Random force value testing is conducted at representative stress points to ensure that the construction results match the design.

IV. Precautions
Membrane Material Characteristics: The fiberglass membrane surface is tensioned to approximately 110% of the design value to compensate for stress loss during use.

Construction Conditions: The supporting structure must be completed, and conditions for component stacking and crane access must be met.

Through the above steps, uniform pretension distribution can be effectively ensured, improving the safety and durability of the membrane structure.