INSTALLATION OF PREFABRICATED CONCRETE AND CONCRETE CONSTRUCTIONS 13. Examination of elements

The alignment ensures that the structures are exactly aligned with the design position. Depending on the type of structures to be mounted, their equipment, joints and conditions for ensuring stability, the alignment is made visually or instrumentally during the installation process, when the structure is held by the mounting mechanism or after installation when it is fixed.

Visual alignment is performed with sufficient accuracy of the bearing surfaces and the joints of structures. At the same time steel roulettes, calibers, templates, etc. can be used.

Instrumental alignment is performed with the difficulty of ensuring the accuracy of the installation of mounting elements and structures by checking only the supporting surfaces, end bases or joints of the assembled structures. It is produced when installing special mounting devices (conductors, frame-hinged indicators, etc.). Instrumental alignment is the most common type of verification of the position of assembled structures in plan, height and vertical positions. In the process of such an adjustment, theodolites, levels, laser devices and devices are used.

A strapless installation has become most prevalent in the installation of prefabricated metal structures (in some cases, reinforced concrete structures). Its main condition is the use of structures with an increased class of accuracy of geometric dimensions in the assembly joints. This allows for installation to install, for example, steel columns, supports and other frame elements with milled bearing ends in the design position, excluding alignment in height and vertical.

Automatic alignment involves the installation of structures with parallel alignment using automatic devices.

When reconciling items:

■ Vertical installation of elements checked by plumb or using a theodolite;

■ horizontal installation check level or level;

■ before installing the columns in the glasses of the foundations, they control their actual dimensions, prepare the foundations for these dimensions — they deepen the nest of the foundation glass or pour the concrete mixture into the glass, more often they put reinforcement pads 1 and 2 cm thick.

During the reconciliation period, the structure should be stable under its own weight, installation and wind loads due to the correct sequence of installation, compliance with the design dimensions of the support sites and interfaces, timely installation of permanent or temporary ties or fixings provided for in the project, as well as ensuring measures for the safe management of construction processes .

Possible maximum deviations from the design position of the elements and structures during installation should be established in the project of production of works, depending on the design solutions, devices and equipment used, welding procedures and other conditions within the limits provided for by the SNiP. The results of the inspection are drawn up by acts of intermediate acceptance of the assembled critical structures and acts of examination of hidden plots with the application of the executive scheme of geodetic control.