Introduction. The use of polymer composites as structural materials for bridge superstructures represents a promising area for scientific research and development, particularly in challenging climatic and geological engineering conditions. The use of polymer composites as structural materials for bridge superstructures represents a promising area for scientific research and development, particularly in challenging climatic and geological engineering conditions. The aim of the work is to identify methods for increasing the efficiency of using polymer composite materials in bridge span structures based on the study of their physico-mechanical char acteristics as part of experimental studies. Methods and materials. The relevance of this research stems from the need to develop a structurally similar model of a bridge superstructure made of polymer composite materials that meets modern stability and safety requirements, thereby facilitating infrastructure development in remote northern regions. The variety of fibers, matrix materials and reinforcement schemes used in the creation of polymer composite structures makes it possible to control characteristics such as strength, rigidity, operating temperature and other physical and mechanical properties of materials. Results and Discussion. The study included a brief overview of the components of polymer composite materials and the development of a testing program, which led to the production and testing of a batch of flat samples using domestically produced materials. Selecting the composition, adjust ing the component ratios and improving the composite's macrostructure allows for optimal performance characteristics depending on the requirements. Conclusion. Tests of flat FRP samples aimed at determining the values of their physico-mechanical, strength and deformation characteristics have been carried out. The test results obtained for FRP are comparable to those of traditional structural materials. The expediency of using fiberglass in highly loaded structural elements is substantiated, which demonstrates the potential for developing a bridge superstructure design from FRP. The prospects for further research based on computational and experimental analysis of nodal connections of elements from FRP are outlined.
The article presents the results of study of reaction products of sulfur with a mixture of higher fatty acids and polyethylenepolyamines. It was found that the resulting materials exhibit elastomeric properties under normal conditions and thermoplastic properties when heated to100-140 °C. The microstructure of the new substances is amorphous-crystalline, and the chemical composition contains compounds with polysulfide fragments and unidentified crystalline and amorphous substances. Using the reaction products into petroleum bitumen at a rate of5 % by weight allows for the production of new sulfur-containing binders for road asphalt concrete, which exhibit greater thermal stability at high positive temperatures compared to known «sulfur-bitumen» binders or pure bitumen.
The problem of determining the limiting load under tension of composite rods with different fiber placement is considered in this paper. The methodology is proposed that is based on the use of a nonlinear elastic material model, and that is an alternative to the classical approaches to determining the limiting load. It is assumed that the ‘‘stress–strain’’ diagram is smooth, but it has an extreme. In this case, the descending branch of the diagram has a horizontal asymptote. This allows avoiding the occurrence of stress concentration and always obtaining the limiting load. In this case, no strength criteria are used. The proposed approach is tested numerically by the finite element method (FEM). Two approaches are used to solve the nonlinear elastic problem. The first is based on the method of successive additional loadings, the second—on the method of successive approximations.
The relevance of this study stems from the need to find effective approaches to transforming former industrial sites in the context of post-industrial urban development, increasing demands on the quality of the urban environment, and the need to reuse industrial heritage sites. This article examines Russian and international examples of industrial site renovation to identify successful practices and formulate typological guidelines for their further implementation in domestic design practice. The goal of the study is to identify the most effective approaches to industrial site renovation and determine the architectural and urban planning solutions that ensure their sustainable integration into the modern urban environment. To identify the key effective tools for industrial site renovation, twenty-two successfully reconstructed sites were analyzed. For each, eight key parameters were examined: the degree of site integration into the urban fabric, accessibility and safety, the quality of public spaces, the preservation of industrial identity, the use of functional hybridity, the preservation and transformation of operational functions, as well as the renovation of façade solutions and the reconstruction of the site's planning structure. The assessment was conducted using a matrix analysis method, which allowed for comparing objects based on a set of criteria and identifying the most effective tools for the comprehensive renovation of industrial buildings into art clusters. The study found that the most successful renovation examples involve the formation of multifunctional art clusters that combine the preservation of industrial identity, the richness of public spaces, the flexibility of new use scenarios, and the preservation of operational functions. The findings of this study can be applied within the framework of domestic urban planning practices when developing strategies for the development of industrial zones and the creation of multifunctional urban spaces.
The results of developing a fiber-reinforced concrete composition modified with multi-walled carbon nanotubes (MWCNTs) for application in monolithic beams are presented. A comparative analysis of six concrete compositions with various combinations of modifying components was conducted. It was established that the complex modification of concrete with steel fiber, superplasticizer "Polyplast SP-3" (1.5 % by cement weight), and MWCNTs (0.0005 % by cement weight) provides an increase in compressive strength by 84.4 % and flexural strength by 2.48 times compared to the control composition. The application of the developed composition allows increasing the strength class of structures from B27.5 to B50 or reducing the consumption of bar reinforcement by 19.2 %. A synergistic effect of the three-component modification system was revealed, attributed to the reduction of water-cement ratio, densification of the cement matrix at the nanoscale, and effective absorption of tensile stresses by the fiber.
