Responding to an array of conditions in Shanghai, Gensler’s team proposed a building design that employs a curtain wall system designed as a symbiosis of two glazed walls—an exterior curtain wall (Curtain Wall A) and an interior curtain wall (Curtain Wall B)—with a tapering atrium in between. The main support for the exterior curtain wall is a horizontal ring beam consisting of a horizontal pipe 356 mm in diameter laterally supported, at 0 meters on-center in Zone 2 and 7 meters on-center in Zone 8, by a radial pipe strut support. This variation is a result of the geometry that included tapering and rotation of the tower.
The horizontal radial pipe strut supports consist of a 29-mm diameter pipe (with varied but mainly 22 mm wall thickness) that transfers the exterior façade lateral load to the inner circular building slab edge. The radial strut pipes are rigidly connected with the horizontal girt while using a hinge connection on the other side—at the interior slab edge steel support—to allow the exterior façade to move up and down relative to the inner structure.
To carry the gravity load of the façade and façade support structure, two 60-to-80-mm high-strength rods (depending on the zone) are hung from the mechanical room/refuge area above, with a robust steel structure designed within, to the horizontal 356-mm ring pipe beams at 4.5 meters (4.3 meters in Zones 7 and 8) on-center vertically at every strut location, including an amenity floor that uses steel bushings instead of perpendicular struts to limit lateral movement. Steel bushings move in vertical direction to allow for expected combined closing and opening movements to be largest at Zone 2, at 4 mm.
This is also where the curtain wall system vertical expansion joint is located. In the horizontal direction, there are total of eight expansion joints, each allowing typically about 56 mm of combined open and closing movement. Special considerations were given to fire protective requirements of the Curtain Wall Support System (CWSS), and additional allowances had to be provided to total vertical and horizontal movements.2