Abstract: The construction of the core tube of Tianjin Goldin 117 Building has many construction difficulties, such as large volume(the maximum single-layer area is 1 072 m²), high structural height(the construction height of the structure is 596.2 m), many changes in storey height(a total of more than 20 storey heights), many changes in wall segmentation, thickness and elevation(the thickness of the external wall is reduced from 1 400 mm to 300 mm), and many stiffness column components.
In order to ensure the progress and quality of engineering construction, the project team integrated a variety of formwork forms at home and abroad, and finally selected the anti-lateral modular low-position jacking steel platform scaffold system for core tube construction, and studied its design principle and composition, installation and construction process and operation points. The research results include:1) The formwork system consists of five parts:steel platform system, support and jacking system, hanging frame and retaining system, formwork system and anti-lateral device. Each part needs to meet the safety and quick requirements of super high-rise construction and its strength and stiffness. 2) In order to adapt to the change of layer height, the formwork system is equipped with the stereotyped formwork according to the standard layer height. The vertical position of the formwork can be adjusted by itself when the formwork frame system is fixed, and the formwork at the end of the core tube needs to be adjusted according to the structure. When the layer height changes greatly, the support column is adjusted by adding non-standard sections. The hydraulic cylinder with large stroke meets the lifting height requirements of different layer heights. 3) In order to facilitate the hoisting of steel members in the core tube, steel plate and rigid column hoisting holes are left on the steel platform, and the horizontal slideway is set up for the steel plate that cannot be in place at one time and slide horizontally to the installation site. The height of the column meets the requirements of the maximum hoisting section. 4) According to the overall construction deployment of the project, after the core tube construction of four layers of sandwich structure, the tower crane is first installed, and then the top die is inserted after the installation of the tower crane is completed. It is planned to install and debug for 30 days. 5) The overall process of jacking formwork installation is as follows:measurement setting-out → hoisting of lower box girder → hoisting of hydraulic cylinder → hoisting of upper box girder → hoisting of supporting column → installation of steel platform truss → installation of hanger and enclosure system → installation of formwork system → installation of lateral resistant device. 6) The installation method of prefabricated steel truss platform truss is "ground assembly, aerial assembly", that is, the platform truss is pre-assembled into short pieces in the manufacturer, transported to the site, and then assembled into pieces on the ground, and then hoisted to the aerial assembly and bolted. The internal and external hangers are assembled into units on the ground, and then hoisted in pieces or blocks.
The application practice of Tianjin Goldin 117 Building has proved that the top formwork system has the unique advantages of supporting column height, carrying out the vertical flow construction of the whole process of steel plate shear wall at the same time, and resisting wind-induced lateral displacement. It has reached the construction speed of 5 days/floor, created good economic and social benefits, and has broad application prospects.