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The paper considers the methodology for assessing the technical condition of welded load-bearing metal structures of operated agricultural hoisting cranes. In the course of the study, the relationship between structural, mechanical and magnetic parameters was established during cyclic elastic-plastic deformation of low-carbon and low alloy steels. Based on the analysis, it was concluded that the dependence of the minimum values of the magnetic parameter on the acting stresses Нр(σ) is influenced by the metal structure and its chemical composition. It has been established that the coarser-grained structure of the studied steels under elastic-plastic deformation contributes to a shift in the minimum values of Нр towards lower acting stresses; an increase in the strength characteristics of steels shifts the minimum of Нр toward large values of s, which must be taken into account when conducting technical diagnostics of the elements of the operating metal structures of hoisting cranes. Based on the results of the study, a method for determining the acting stresses in the elements of the metal structures of hoisting cranes was developed, which, by the nature and magnitude of the change in the residual magnetization of the scattering field during their stepwise loading (unloading), allows judging the magnitude of the acting stresses. The work also presents a methodology for assessing the technical condition of welded load-bearing metal structures of hoisting cranes based on the integrated use of passive flux-gate and other control methods, which allows determining the acting stresses used in strength calculations in the identified hazardous zones of concentration of stresses in the elements of metal structures.

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Since ancient times, limestone has been known as an inexpensive and reliable building material. The main problem of limestone materials in the construction of buildings is its reduced longevity due to various factors, such as wind and rain. These factors have a huge impact on the strength characteristics of the building material, so adherence to special recommendations is an important practical task. A review of literature on the problem of durability and the use of limestone is presented. With the help of experience, the strength of nummulite limestone is established. The analysis of the obtained data is made, as well as its comparison with the indices of other artificial and natural stones. The main methods of strengthening the structures made of limestone are considered at three different stages. Practical recommendations for minimizing the impact of negative factors on this material are given.

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