The method of fixing soils is injection filling of voids, which is produced by binding materials - cements, clays, bitumen, etc., and sand, sawdust, loam, suspensions are used as inert fillers. It is possible to improve the quality of cement composite solutions through the use of reinforcing additives, which in the future will ensure a high degree of reliability, safe operation of facilities. The paper considers the possibility of involving nano-additives in grouting compositions, such as aluminosilicates, in particular boehmite. Studies of the hardening processes of composite solutions in the presence of bentonite grade P1T1 with different content of boehmite have been carried out. The concentration of boehmite at which the rate of hardening of the composite solution is maximal is determined. In order to save cement, the effect of the surfactant on the strength of the composite solution was investigated, it was found that the 20% introduction of the surfactant into the composite solution gives a strength that almost coincides with the zero sample.

Keywords: safe operation, plugging compositions, boehmite, surfactants, strength, structure formation, optimal concentration, nanosystem, modifier, cement

The issues of unification of metal truss trusses are considered, the results of comparison of technical and economic indicators are presented, the cost of unified and non-unified trusses is determined. Metal truss trusses are lattice structures consisting of individual rods. The design of such trusses consists in determining the forces in the rods, followed by the selection of their cross sections. In this situation, we are dealing with a large number of parts and standard sizes of sections. All this leads to an increase in the labor intensity and cost of manufacturing farms. In order to reduce these indicators, after selecting the sections, the elements of the farm are unified. For this purpose, the entire upper and lower belts are usually made of one larger section, which reduces the number of main parts. For the convenience of manufacturing trusses (reducing the number of standard sizes of rolled metal ordered by the plant), all other grid sections are reduced to 2-3 sizes. Naturally, such unification leads to an increase in the mass of the entire farm and the cost of all rolled metal used.

Keywords: truss, unification, seriality, cost, installation

The article presents calculation of the cost of overlappings from LSTK and wooden ones. The floors of the two-storey house with a span and overlap with a span of 12 m were calculated. Calculation of the cost of materials is presented for each option. In conclusion, conclusions were drawn on the rational use of material types for each of the calculated spans.

Keywords: light steel thin-walled structures, LSTK ceiling, wooden flooring, reduced characteristics, effective cross-section, construction

The lack of standards for the calculation of lightweight thin-walled steel structures allowed low-quality producers to save on production, which endangered the people who exploited such buildings. The appearance of normative documents for the calculation of thin-walled structures entails responsibility for the affirmers of these normative documents. In Russia, such norms appeared relatively recently and the purpose of this study was to compare domestic normative methods of calculation with non-significant ones. During the presentation of the study, the concept of a reduced (effective) section of a beam when working on bending was considered. Also, the same stages of the calculation methods were noted, indicating the places where the methods differ in their opinions. The result of this study is a comparison table for the basic geometric characteristic for obtaining the bearing capacity of an effective torque element of resistance. An analysis was carried out and a conclusion was drawn on these values.

Keywords: steel structures, light steel thin-walled structures, thin-walled beams, reduced cross-section, bending work, C-shaped profile, effective cross-section, effective area, effective resistance moment

In this paper, it is proposed to update the values ​​of the bearing capacity of the hinge attachment of the beams to the columns on 2 bolts. A comparative analysis of the bearing capacity of the assembly presented in the 2.440-2 release 1 series and calculated according to modern building codes is carried out. Five calculation formulas were obtained for the five possible limiting states of the node. A table with the values ​​of the limiting forces perceived by the connection is presented. A possible variant of improving the assembly is presented, by including a support table in the work.

Keywords: bearing capacity, metal structures, hinged unit, structural solution, connection of elements, limit state