Introduction. The data of the results of the inspection of steel structures are given, based on the analysis of which strength classes of structural steels are established. The goal has been solved by determining the chemical composition of metal structures and full-scale tests of the mechanical characteristics of steel structures, followed by a calculated conversion of the hardness index HB to the value of temporary tensile strength σv. Materials and methods. Strength indicators of metal structures are determined by non-destructive express method by means of a portable hardness tester of the dynamic principle of action. For the calculated determination of the breaking strength σv adopted the average lengthening coefficient kδ. By its value, the indicators of elongation and contraction are established, as well as the yield strength of the metal. Based on the calculated standard indicators of plasticity (δ, ψ) and strength (σv, σt), the complex criterion C equation is compiled. Using it, calculated the uniform elongation δр and the transverse narrowing ψр, which were used to assess the tensile strength (Sv, Sk) and fatigue (σ–1, τ–1). The chemical composition of small-sized samples in the form of metal shavings was determined by x-ray fluorescence. Additionally, the chemical composition of the steel was monitored using a scanning microscope with an attachment for determining the chemical composition by energy dispersive x-ray spectroscopy. Results. The proposed research method makes it possible to conduct full-scale tests of metal structures and reduces the complexity of the selection and delivery of samples for laboratory research. The results obtained by both methods are correlated with the source data (design documentation for the object of the survey). Conclusions. An integrated method of sampling and direct measurement of hardness on site allows one to determine the chemical composition of metal structures, the grade and type of structural steel and its mechanical properties. At the same time, the scientific novelty is the given technique as a whole, which is characterized by a significant reduction in labor costs and minimization of damage to the objects under study.
Introduction. In landmark buildings, floorings and roofs are performed as vault and arch systems. For accommodation of horizontal forces in the arches, aerial braces are used. Aerial braces of an arch system are a tie made of wrought iron with a cross-sectional area from 10 to 50 cm2. In the scientific and technical literature, information on aerial braces is extremely poor. Materials and methods. To assess the impacts of temperature deformations on the bearing strength of the aerial braces, a computational analysis was performed. On the basis of data on standard structural schemes of the landmark buildings, the characteristic length of aerial braces was taken into account. Averaged climatic data calculated on the basis of weather observations for the period 1988–2017 for 13 climatic regions of Russia were analysed. Since the data on the temperature of the closure of the distance piece system are irrevocably missing, two variants of the outdoor temperature were considered for the installation of the aerial braces: zero and the maximum summer temperature. Results. Calculations were carried out and the strain arising in the aerial braces at the corresponding temperature elongation values obtained under recognition of the different temperatures of arch system closure was determined. Totally 78 temperature graphs were obtained and analysed for different climate areas, with different closure temperatures of arched systems. Conclusions. It was found out that, for the assessment of the impacts of temperature deformation on the bearing capacity of aerial braces, the actual temperature of the arch system closure is decisive. The safety factor of the bearing strength of aerial braces of arch systems for most climatic zones exceeds 50 % and can reach 92 %. At the same time, for two areas with significant negative temperatures in the winter period, the utilization ratio of aerial braces can reach 0.6–0.63. The maximum temperature elongation of aerial braces with a length of 6 m does not exceed 3 mm in case of mounting at the maximum summer temperature and 2 mm at the zero point.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.