ROOFING CONSTRUCTION TECHNOLOGY OF SADDLE-SHAPED OVERHANGING STEEL STRUCTURE RETICULATED SHELL SKIRT BUILDING OF HANGZHOU GATE SUPER HIGH-RISE BUILDING

 Hangzhou Century Center, which is the tallest building under construction in Hangzhou and the tallest twin tower building in the Hangzhou Bay area, is known as the gate of Hangzhou. The wings of the two towers of Hangzhou Gate, together with the surrounding Olympic Sports Center, natatorium, International Expo Center, as well as the civic center, international Convention center, and grand Theater on the other side of the Qian River, form a "seven-star bright" urban picture. The Gate of Hangzhou is like a cloud floating in the seven stars, with a strong sense of design and visual impact.  

The main body of Hangzhou Gate is composed of symmetrical 63-story east and west towers, with a building height of 302.6m and a total construction area of about 532,500 square meters. The east and west towers are connected by steel arch Bridges on the 1st to 6th floors above ground. The maximum span of the bridge is 85m at the north and south ends, the minimum span is 55m in the middle, the width is 60m from south to north, and the arch height is 19m. The arch feet are supported on the steel-concrete columns set independently in the basement of the tower. The whole steel arch bridge is completely wrapped by the saddle-shaped suspended steel structure reticulated shell roof and the suspended side walls on the north and south sides (referred to as "suspended roof"). The suspended roof is cantilevered from the end of the cantilevered steel truss on the edge sealing beam on the 22nd floor (elevation 103.45m) of the twin towers to the corresponding height on the 7th floor of the tower, with a maximum suspension height of 65m. The cantilever roof is mainly composed of 47 parabolics "catenary lines" with different lengths from east to west and 39 transverse parabolic connecting beams from south to north. Both catenary lines and transverse connecting beams are made of H-shaped steel. Cylindrical steel drum joints are designed at the nodes of the mesh shell. The overhanging roof and side walls are supported by three horizontal tie rods on the 11th, 14th, and 18th floors of the east and west towers to provide lateral restraint. The overhanging roof realizes the perfect transition between the curved facade of the towers on both sides and the roof of the steel arch bridge, fully displaying the beauty of the spatial curved surface.  

The cantilevered roof of Hangzhou Gate is a super-high-altitude cantilevered steel structure reticulated shell with a large area and unique shape, which is the most difficult and complex part of the whole project. It has the following typical structural characteristics:  

(1) Overhanging stress system: The dead weight load of the entire overhanging roof is entirely borne by the steel truss suspension extending from the 22-floor edge sealing beam of the east and west towers, while the lateral three horizontal tie rods only play a role of restraint and do not bear the vertical load.  

(2) Saddle-shaped space frame structure curved surface, the maximum height difference of a single catenary in the east-west direction is nearly 65m, and the maximum height difference of a single connecting beam in the south-north direction is nearly 10m, indicating great spatial curvature.  

(3) Semi-rigid space reticulated shell, single catenary twisted by multi-segment h-shaped steel through steel drum joints rigid connection to fit, suspended roof not only has the flexibility of catenary structure but also maintains a certain stiffness.