Research On Construction Technology Of Long Span Prestressed Concrete Floor Of Existing Buildings

With the acceleration of urbanization and the increasing demand of people on the function and spatial layout of modern building structure,prestressed concrete structure is gradually used in various engineering construction.The cross-section size of the long-span prestressed concrete structure is often large.During the construction period,the floor weight and construction load are very large,which is very easy to produce deflection deformation.Before the floor tension and prestress,all the loads are borne by the temporary formwork support system under the beam body.Therefore,during the construction of the large-span prestressed concrete floor,the construction process of the prestressed concrete floor is very large,The design of the structural formwork support system is particularly important,and the quality of construction directly affects the safety of the whole structure.Based on the construction of a large-span prestressed concrete floor structure of an existing building in Shijiazhuang,aiming at the characteristics that the distance between the beam bottom and the roof of the existing building is too small during the construction of the floor,this paper completes the formwork support scheme of the large-span prestressed concrete floor,analyzes the construction scheme of the large-span prestressed concrete floor structure,and finally analyzes the floor structure during the construction period through the finite element software The main work is as follows.(1)According to the construction characteristics of the project,the site investigation of the existing buildings is carried out,the space where the formwork support can be set up at the lower part of the large-span prestressed concrete floor structure and how to build the formwork support system are analyzed,and the construction scheme of the formwork support for the prestressed concrete floor is determined.(2)Combined with the construction scheme,the strength,stiffness and stability of the supporting components are analyzed.In order to ensure that the existing building will not be damaged,the bending and shear capacity of its structural members are calculated.The results show that the supporting scheme of the template system is safe and feasible.(3)Using Midas Gen finite element analysis software,established the prestressed concrete floor model of frame structure,analyzed the displacement and deformation of the floor structure in the construction process,obtained the influence law of prestressed tension on the floor deformation,through adjusting the size of prestress,made the deformation difference of each part of the floor in a small range,at the same time,analyzed the frame column before and after the application of prestress and the upper part in the construction process The change law of the displacement of the top of the column after the floor load is applied.(4)This paper summarizes the formwork support process of each component of the floor structure in the construction process of the project,the construction technical points and the treatment methods of construction joints when the prestressed concrete is tensioned.