Until recently, in the practice of high -rise construction of structures (Koprov, Silov) built in sliding formwork, vertical control was carried out by plumbing.
This method of labor -intensive and does not provide satisfactory accuracy of measurements. In recent years, during the construction of the Kopov in the Donbass, to check the position of sliding formwork, vertical visualization devices-anti-aircraft priests like PZL.
For this, special visir stamps are strengthened on the axes of the intersection of formwork planes. The stamps are drawn on transparent material or a grid of squares with a side equal to 1 cm, printed on a triaceta photograph, and digitizing after 5 cm.
The anti-aircraft sediment is installed sequentially under the stamps so that it is possible to control the verticality of the shaft of the tower, the elevator compartment and the position of the outer walls. The number of visitor brands and their location are determined depending on the form of the formwork and the height of the copra.
When erecting cops with a height of not more than 50 m, the number of marks can be reduced to two in the mine and one brand in the elevator department. In this case, the determination of the position of the external walls is carried out after the end of their construction by profile survey of external faces of the copra, performed by known methods using theodolite and measuring rail.
In the shaft part of the head of the brand, the brand is attached to wooden gestures that support the working floor of the formwork, or on the brackets welded to the circles of the formwork. Peripheral brands roll to wooden gestures supporting the floor of the visor, or directly to the floor.
To ensure visibility under the brand in the suspended forests and in the visors of the formwork, open openings equal to the area of the brand. Each time after the end of observation, the openings should be closed.
To simplify the subsequent processing of observations of the brand, it is necessary to place so that the scales are parallel to the axes of the barrel, an increase in digitization on the corresponding scales was the opposite of the increase in the coordinate X and the axles of the barrel and that the center of the brand and the installation point of the anti-aircraft industry are located approximately on the general vertical.