Wechat headquarters building ushered in a critical node

Pearl River wave long sea, spring tide microstrip fall xiaguang. In the beautiful Pearl River, The Second Engineering Bureau of China Construction Engineering Co., Ltd. contracted to build Tencent Guangzhou headquarters building project, the future wechat headquarters building. Ushering in the key node -- the installation of the cantilever roof of 28m and 750T was completed. This marks the completion of the installation of all four large single-sided cantilevered gardens, hills, villages and rooftop views!

As the largest single cantilever structure in China, we enjoy its construction highlights

Tencent guangzhou headquarters building is 206.7 meters high, with four large cantileted platforms extending from the 14th, 23rd, 32nd and 38th floors of the south tower, respectively creating four kinds of landscape of gardens, hills, villages and rooftops. It is committed to providing a poetic garden-like office environment for wechat employees. But the construction and installation of the four cantilevers, which can be as long as 28 meters and weigh a total of 1,840 tons, has presented architects with some puzzling mathematical olympiad problems.

At the beginning of the design, in order to ensure the visual effect of the building, the cantilever did not use any roof support or suspension structure. In particular, the 38-story cantilevered platform truss and steel beam with a total weight of about 750 tons and an area of 1657.6 square meters, which is about the size of 4 standard basketball courts, are the largest single-side cantilevered structure in China. A tensile deformation of 1 mm is a structural safety hazard, and without any design for a down-to-top tensile deformation, 100 mm will occur on the top of the core tube.

In the process of cantilever construction, in order to avoid the damage caused by the post-span tension of the cantilever to the concrete, the project adopted the scheme of "embedding prestressed steel rod to offset the remaining tension", that is, 8 prestressed steel rods were installed on the external wall to increase the post-tensioning prestress to offset the tension. In this way, the weight of the floor is skillfully transferred back to the core cylinder and the tensile deformation is eliminated.

Once the deformation problem was solved, the actual installation was challenged. Due to the long length of the cantilever, the weight of the single member, and the location of 200 meters in the air, temporary support cannot be set below the installation, which brings another big problem to the cantilever installation.

In order to ensure the smooth installation of the cantilever, the project adopts the way of lifting in sections for installation. Just like joining "Lego" blocks, temporary fixed connecting plate and cama plate are used to assist the interface of overhanging member, and then component installation correction is carried out to ensure the accuracy and safety of installation of single member

In the process of cantilever installation, the project also combines the "smart site system" to monitor the on-site weather conditions such as wind and rain in real time. Once the safety "red line" is triggered, the construction will be stopped immediately to ensure that the cantilever installation is safe and stable, and the construction of the largest vertical cantilever platform in China is suspended in the pearl River cloud.

New node, new journey, excellence, uphold the spirit of ingenuity. The Second Construction Bureau will strive to create a unique aesthetic architectural space, interpret the spirit of overcoming difficulties with practical actions, empower urban construction, and inject new momentum into the Guangdong-Hong Kong-Macao Greater Bay Area.

This article is reprinted from the public account of China Construction Second Bureau