33407 2304-6295 11 74 2018 1-38

RAR RUS 7-16 Strakhov Dmitry Aleksandrovich sdaleks2008@rambler.ru Sinyakov Leonid Peter the Great Saint Petersburg Polytechnic University Vasilenko Anastasia

Polytechnicheskay, 29

High-strength concrete bending elements The object of this article research is the reinforced concrete bending elements (beams) with the use of highstrength concrete. In the first part of the paper, the effect of concrete grade increasing on the load-carrying ability of beams depending on reinforcement percentage was considered. According to the results of the calculation, it was found that with the same sizes of a normal cross-section and single reinforcement of only the tension side, the most expedient is the use of high-strength concrete in beams with high value of reinforcement percentage. At low value of the reinforcement percentage, the increase of a load-carrying ability with change in concrete grade is insignificant. In the second part of the paper, the calculation of a material cost of the 1 linear meter of the beams is executed and the field of the use of high-strength concrete in relation to the considered case is defined. 10.18720/CUBS.74.1 69 reinforced concrete beam; load-carrying ability; grade of concrete; percentage of reinforcement; cost; utilization efficiency https://unistroy.spbstu.ru/article/2018.74.1/ 74_1.pdf

RAR RUS 17-25 Kazan State University of Architecture and Engineering Mukhametrakhimov Rustem muhametrahimov@mail.ru

1, Zelenaya st., Kazan, 420043 Russia

Kazan State University of Architecture and Engineering Galautdinov Albert Polyfunctional chemical modifier for gypsum cement compositions The wide range of chemical modifying admixtures is used in gypsum-cement-puzzolan binders production. Complex chemical admixtures with multi-functionality of the effect have more powerful capabilities in controlling setting process of binders based on gypsum and portland cement. In this regard, production of the polyfunctional complex admixtures with the purpose of improving the performance properties of gypsum-cement-puzzolan compositions is a relevant objective and necessitates undertaking experimental studies. This work objective consists in studying characteristics of interreaction of chemical modifiers in structure and gypsum-cement-puzzolan binders’ properties, in determining their mechanism of synergistic interaction, in production and optimization polyfunctional complex admixture (CA) composition that helps to improve performance properties of gypsum-cement-puzzolan stone based on low-graded gypsum binder. In consequence of undertaken studies the mechanism of synergistic interaction of superplasticizing admix “Best-TB”, polycarboxylate superplasticizer “Odolit-K”, organosilicone compound “N-oktiltriehtoksisilan” was determined. With the use of these chemical modifiers the polyfunctional complex admixture that helps to improve the performance properties of gypsum-cement-puzzolan compositions was produced. Based on mathematical experimental design techniques optimum doses of above-named chemical admixtures in composition of mixture were determined. Elaborated polyfunctional complex  admixture with tailored composition helps to raise coefficient of softening of the products based on studying type of binder to 0.98, ultimate bending strength – by 86%, frost resistance – by a factor of 4.2 10.18720/CUBS.74.3 69 gypsum cement mixed binder complex additive polyfunctional additive chemical modifi https://unistroy.spbstu.ru/article/2018.74.2/ 74_2.pdf

RAR RUS 17-28 Peter the Great Saint Petersburg Polytechnic University Zhukov Vladimir

Polytechnicheskay, 29

Kolgatin Sergey The use of similarity criteria in the study the mechanical strength of metals During the construction of high-rise buildings, a significant attention is paid to the quality of construction materials. In our article we are presenting the possibility of using the criteria of similarity of the processes of low-cycle and high-cycle fatigue in the creation of metal structural materials. The composition of the criteria includes determining values, the sizes of which are not determined by measurement in the process of testing materials. The efficiency of the presented criteria is demonstrated by the example of selection of titanium alloy compositions for marine engineering, structural and technological parameters of structural steels. The invariance of the similarity criterion of low-cycle fracture in artificial seawater of titanium alloys with yield strength up to 785 MPa was experimentally established. The possibility of evaluation of the theoretical stress concentration factor of welded elements on the test results of specimens under symmetrical cycle of stretching-compression is shown. 10.18720/CUBS.74.2 69 Similarity criteria; low- cycle fatigue; high- cycle fatigue; titanium alloys; constructional steel; invariance; https://unistroy.spbstu.ru/article/2018.74.3/ 7403.pdf