The durability of prefabricated buildings largely depends on the quality of embedded parts and welded joints between them. Steel embedded parts and welds under the action of an aggressive medium penetrating through the gaps and pores corrode, which leads to weakening and destruction of the steel joint between the structures. By permanently fixing the structures to a greater degree prevent the negative influence of the environment.
One of the main tasks in the construction of buildings is a reliable connection of the individual structures to each other, since the quality of such a connection to a certain extent determines the quality and reliability of the mounted structure. Connections element have three types: seams, seams and knots.
Stitches - the most common combination of elements; these are all horizontal and vertical planes, cavities between adjacent elements. The cavity between the adjacent floor panels, the floor panel and the bolt wall, on which it lies, the plane of the joint between the floor panel and the wall panel installed on it are the seams of the structures to be connected.
A joint is a more responsible articulation of two framework elements, this is a junction, and to a large extent a load transfer zone of one framework element to another. The joint is the place where two columns are connected to each other vertically, the place of supporting and transferring the load from the crane girder to the column console, the joint of the truss and the column are similar.
Metal structures are fastened with bolts and often additionally with welding.
Reinforced concrete columns of one-story industrial buildings and columns of the first floor of high-rise buildings, embedded in the glasses of foundations, are fixed by pouring concrete mix into the glasses, while the gaps between the column and the walls of the glass should not be less than 3 cm for the free passage of concrete mix. The time for recruitment of 70% grade strength with aluminous cements is 3 days, with ordinary Portland cement it is 7 days.
The remaining reinforced concrete elements are fixed by welding the embedded parts. Joints between such frame elements as slabs and girders, girders and columns, etc. have different designs. In accordance with this, in the projects indicate the methods of sealing: the sealing of welded assemblies, the caulking, the sealing of joints with mortar.
Prior to the start of welding work, check that the structures are installed correctly. Releases reinforcement, embedded parts, linings and lining should be thoroughly cleaned from the influx of concrete, bitumen, paint, rust and other contamination with a metal brush, hammer, solvents, torch flame immediately before stitching.
When performing welding work under adverse weather conditions, you need to use tools (tents, screens) that protect the workplace of the welder from precipitation and the effects of sudden gusts of wind. Welding work can be performed at temperatures up to -30 ° C. At negative temperatures, welding is carried out according to the usual technology, but with increased amperage.
Corrosion protection of embedded parts is carried out in the manufacture of structures in the factory. To restore the coating after welding in the conditions of the construction site, metallization is used - the application of a zinc-polymer coating with a protective coating unit. The thickness of metal coatings and the metallization layer should be: for zinc - at least 120 ... 180 microns, for aluminum - at least 150 ... 250 microns. The thickness of zinc coatings obtained by hot-dip galvanizing should be 50 ... 60 microns.
Seal joints consists of the following operations: caulking, waterproofing, insulation, monolithing, sealing, surface finishing. Filling seams of floor slabs and coatings, sealing joints and pouring seams of wall panels contribute to increasing the rigidity of the frame, improving its thermal and insulating characteristics
Works on sealing joints are carried out during installation and perform overlapping. If the design provides for the processing of the joint from the outside, this operation is carried out in the course of installation on the first floor from a stepladder, and on subsequent ones - from mounted cradles. The cradle is hung on the ceiling and fastened to parts of the building, most often to the mounting loops of the floor slabs. The cradle is rearranged along the building with the help of a mounting crane.
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