The three stations of the Shanghai Subway Station Line 6 are covered by 16 inverted umbrellas each. The umbrellas are shaped with a cable borderline at the high point and have a drainage system integrated at the lower part.
It is known that PTFE can absolutely not be folded. In the designed configuration it was a problem how to weld the last FEP film seam successfully to make the whole into the shape of an umbrella. The common way is to use aluminium clamps to put the last two welded pieces together and wrap over the clamps some film of the same type. However, the client insisted that the umbrella should be a whole unit and they did not agree to change the way of connection. So when the fabric was being welded and installed we had to find a solution for the following problems:
1. How to make the last welding seam?
The last welding seam was welded on site with a width of 10cm.
2. How to manage the installation?
First the welding desk was positioned according to the 3D shape of the welding seam, next the welded fabric was wrapped around the steel structure and then it took five minutes to weld the last seam.
3. How to drain the rainwater?
The rainwater is evacuated through the bottom circle of the inverted umbrella. The steel columns supporting each umbrella were designed to be equipped with drainpipes and were galvanized inside from top to the bottom to create an integral drainage system that is unperceivable. These columns are connected to the underground-drainage system of the subway station.