Modular Design And Application Of Jack-raising Formwork In Super High-rise Core Tube

In general, more than 100 m high or over 40-storey building is internationally known as super high-rise building. With the development of economy and technology,the height and the number of super high-rise building are increasing. Structure of super high-rise building generally uses the structure of "outer frame + inner cylinder",in which the construction of concrete core tube structure is a major factor restricting the construction of super high-rise building. In construction of concrete core tube structure, jack-raising formwork is a new mold system after sliding formwork and climbing formwork, and is one of the "10 new technologies in the construction industry(2010)", which is promoted by the Ministry of Construction.Currently, the jack-raising formwork has been only applied in a few projects. A circulating of jack-raising formwork is poorer and a one-time investment is large in the application of jack-raising formwork. Design and production of jack-raising formwork is executed by the construction unit. Because of the lack of professional third-party, this increases the difficulty of management in jack-raising formwork application for the construction unit. And to some extent, it hinders the promotion of jack-raising formwork. Based on the East Tower Project of Zhenjiang Suning Plaza,modular design and application of jack-raising formwork is expounded in this paper,so as to promote the wide application of the jack-raising formwork, and improve the cycle utilization of the formwork and ultimately achieve the professional development of the formwork. The research work is mainly as follows:1. On the basis of reading and studying the relative references and research,firstly this paper introduces the composition and process principles of jack-raising formwork. Secondly it analyzes the construction technology of jack-raising formwork,including standard floor construction, the coordination of vertical transportation equipment and construction safety control and so on. Finally by comparing the jack-raising formwork and traditional formwork, it generalizes the advantages of jack-raising formwork.2. The origin, basic theory and achievement in the construction industry of modular design is systemically described, and the demand for modular design in jack-raising formwork is analyzed on basis of the above. Through theoretical study,this paper presents a modular design method of jack-raising formwork, which is to firstly set up the module database of jack-raising formwork and then to select and fabricate module according to the design requirements of the specific project.3. According to the existing research on the assembly structure design of jack-raising formwork, this paper sets up a module database of a four-fulcrum jack-raising formwork. And in view of the complexity of the calculation in the jack-raising formwork, it provides the calculation method for structure safety of the modular jack-raising formwork, which can guide the practice of engineering application.4. In the east tower project of Zhenjiang Suning Plaza, for example, this paper analyzes the application of four-fulcrum modular jack-raising formwork. Firstly, it selects and fabricates the module according to the project characteristics. Secondly, it completes structure calculation and analysis. In the structure calculation and analysis,this paper uses finite element analysis software Midas Gen to establish a main support structure model. The calculation and analysis is divided into two cases. One is construction phase, the other is lifting phase. Lifting phase is the most adverse circumstances in which only the lower box girder supported on the core tube wall.Based on the analysis results, some modules are adjusted, such as oblique lace bar column, diagonal struts, supporting box girder, etc.5. This paper analyzes the assembling and dismantling process of a four-fulcrum modular jack-raising formwork. Its main support structure module is made to order,but beyond that, some other modules are rent, such as Scaffold, template, oil cylinder,control device and so on. A circulating of the jack-raising formwork is richer and a one-time investment is smaller in the application.