The article is devoted to determining of the thermal reliability rates of CFS wall panels based on three thermo-technical failure criteria - reduced heat transfer resistance, exceeding the values of the temperature difference between the reduced temperature of the inner surface of structure and internal air temperature above the permissible temperature values by the sanitary requirements and criteria of reduction of local values of the inner surface temperature to the temperature of vapor-liquid condensation. With increasing coefficient of variation of thermal conductivity from 2.28% to 20%, the probability of refusal of wall panels of light steel thin-walled structures, under the criterion of the specified heat transfer resistance, is increasing from 9,85´10-7 to 0,015 respectively.

The article analyzes one of the ways to increase the heat-protective properties of thebuilding corner - rounding the outer surface of the outer wall the corner . The walls of houses nearthe outer corner, due to their configuration, have less heat-insulating properties than the walls inother areas. This is due to the fact that the area of heat flow perception on the inner surface of thewalls at an angle less than the area of heat transfer on the outer surface. Convective heat exchangenear the inner surface of the corner, due to the inhibition of air movement is less than in other areas,so the amount of heat coming from the indoor air to the wall surface is less. For climatic conditionsof Poltava region the research of temperature fields of calculated sections of the wall (withoutrounding of a corner, with rounding of a wall of various radius an external surface) with definitionof a heat stream size, the minimum temperature on an internal surface of a wall and the resulted heattransfer resistance is carried out. The dependences of the rounding radius of the wall outer surfaceon the heat flow passing through the design area of the wall outer corner, brick consumption withinthe design area, insulation consumption within the design area, the amount of room area reductiondue to rounding the wall for five design schemes. The analysis of dependences the constructed graphsshowed that the intensive reduction of the heat flux passing through the calculated section occurs ata radius of the wall outer surface rounding of 0.9 m and more; a slight decrease in the area of theroom due to the rounding of the wall occurs to a radius of curvature of 1.4 m; intensive reduction ofbrick volume within the calculated area occurs when the radius of curvature is more than 0.8 m,similarly to mineral wool up to 0.7 m. It is determined that the optimal radius of curvature of theouter wall is 0.8 m, it will increase the thermal properties of the angle and reduce the heat transfercoefficient by the transmission of the external enclosing structure of the building as a whole.

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The article presents the results of stability calculation of reinforced concrete columns using light steel thin-walled structures investigation. Two steel thin-walled profiles of type “C” or “∑” were used as the steel shell of such columns. The profiles were combined in the form of a box section with bolts. To increase the stability of the shell, the inner cavity was filled with concrete with lightweight aggregates. Technique of steel thin-walled elements stability calculation with consideration of concreting and joint work of the whole structure involves two types of calculation: for central compression and for joint action of compression and uniaxial bending. To verify the analytical calculations, a computer simulation was performed, which proved the correctness of the theoretical calculations and made it possible to clearly observe the different forms of column stability loss at different coefficients of overload. It was found that the increase of bearing capacity due to the thickness of the profile varies within 2-10%. For smaller profiles this difference is significant (10-23%), and for larger profiles - smaller (5-8%). This is due to the complexity of the manufacturing technology and the cost of materials.

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