Super large section frame column post tensioned bonded vertical prestress Construction method
The post tensioned bonded vertical prestressed construction method of cast-in-place concrete super large section frame column has the following characteristics: 2.1 Prestressed reinforcement installation Prestressed reinforcement installation has two different forms, namely "first through construction" and "second through construction". According to different forms of design, corresponding measures shall be taken when installing prestressed reinforcement in place, Especially for the prestressed reinforcement of the first through construction, since the anchorage end is generally located inside the concrete structure, the prestressed reinforcement is required to be installed from the bottom to the top at one time, and a special operation platform must be set up to stack the prestressed reinforcement. 2.2 The form of prestressed bellows is compared with the conventional horizontal prestressed construction. When the cast-in-place concrete frame column with super large section has bonded vertical prestressed construction, because the steel strand and metal bellows are flexible materials, it is difficult to fix the bellows and steel strand bundles during construction, and it is impossible to ensure the vertical construction of the bellows to the top, Therefore, the post tensioned bonded vertical prestressed internal prestressed reinforcement of the super large section frame column shall be installed by steel pipe forming holes, and the prestressed tendon shall be constructed by embedding the steel pipe in sections and then passing through the steel strand. 2.3 The prestressed hole at the side of the frame column is reserved with cast-in-place concrete structure. The anchor end of the prestressed reinforcement with bonded vertical prestress in the post tensioning method of the super section frame column is generally located between the bottom of the structure and the upper floor, that is, the prestressed reinforcement can be used in the post through construction. Therefore, the reserved hole is set at the side of the prestressed frame column, and the foam is placed in advance, which will be chiseled out after the later formwork removal, At the same time, adjust the arrangement of the main reinforcement of the prestressed frame column in the reserved opening area. 2.4 Setting of grouting holes for prestressed frame columns Due to the influence of the height of prestressed frame columns, in order to ensure the compactness of the prestressed duct grouting, grouting holes are set at the fixed end of the prestressed tendon (first through construction), or grouting holes at the fixed end (later through construction), and 2 to 3 grouting holes are set in the middle section of the duct, each grouting hole is about 300mm above the floor. 2.5 End structure of vertical prestressed tensioning Since the main reinforcement of the frame column is designed as large-diameter reinforcement, in order to minimize the impact of bonded vertical prestressed tensioning on the main reinforcement of the frame column by the post tensioning method, while ensuring that the installation of the steel structure at the top of the frame column is not affected, "external" and "internal" end structure measures can generally be adopted. 2.6 Cooperation between different types of work As the prestressed works belong to professional construction, there are cross operations with the main civil structure construction and steel structure construction, corresponding special technical disclosure shall be carried out before construction to ensure the smooth and orderly construction of various types of work on site.
