Our research work on the physical and mechanical properties of centrifuged concrete, the strength and deformability of cylindrical and conical transmission towers made it possible to reveal some incorrect calculations according to the old and new standards. To identify discrepancies in the calculations for the supports with annular section according to the SNiP 2.03.01-84 and according to the SP 63.13330.2012, we carried out the numerical experiments on the example of the transmission tower supports. As the test sample, the cylindrical transmission tower according to the Certification System GOST 22687.2
Numeral experiments to study influence on design strength of conical poles, limitations of crack width and breaking strain have been conducted. The analysis of influence on conical poles crack strength and deformability and relation between areas of prestressing steel and total area of steel (Asp/As,tot) has been performed. Research has revealed that dependence of crack width on relation between Asp/As,tot for all types of conical poles is close to linear. Percentage of reinforcement μs, tot % does not influence this dependence. A moment of force increase caused by vertical load Mv/M leads to a significant increase of crack width. Presence of prestressing steel (Asp/As,tot) has the greatest influence on the deflection of conical poles. Still total percentage of reinforcement has little influence on a type of function fпр=f (Asp/As,tot). Calculations of poles made according to a strain pattern showed that regulations understate approximate value of deflection. For that reason, it is advisable to make calculations of poles CONS22, CONS26 according to a strain patter.
A numerical experiment was carried out to study rigidity, critical force, and bearing capacity of reinforced concrete racks with annular section under short-term and long-term loading. The effect of long-term loading was estimated in the numerical experiment by changing the coefficient φl from 1 to 1.8 times 0.2, as well as the modulus of deformations Eb,τ, taking into account the operating conditions (W = 40-75%). At the same time, the external load on the rack N was taken in the experiments as a multiple of the critical force Ncr from 0.2 to 1.0, and the relative eccentricity δe of the load application varied from 0.15 to 1.35, which made it possible to estimate the stress state of the struts in an extended range of possible loadings. The results obtained made it possible to identify qualitative and quantitative regularities of rigidity changes, critical force and bearing capacity of annular struts during short-term and long-term load application.
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