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Tkachov A. V., Tkachov O. A.
Hoisting and transport equipment, 2020, №1(62)
This paper addresses issues related to the load-bearing capacity of pre-tensioned bridge cranes. The solution is to use a new circuit solution to unload the main beams of the crane and to study their static rigidity at any place of temporary loading. A mathematical model of a bridge crane with prestressed beams is presented, which is based on the general theory of stability of elastic systems. In this paper, we obtained equations of the curve of deflections of this beam, which allowed us to consider and analyze the influence of eccentrically longitudinal forces on its stress-strain state. According to the results of the obtained equations, the study of the static stiffness of the main beam, depending on the nature of the external temporary load.
An analysis of the results revealed that the use of the proposed circuit solution minimizes the curvatures of the overhead structure when finding a trolley with a load above the support. In addition, it was found that when working a bridge crane with cargo in the middle of the span, the deflections of the span structure do not go beyond the regulated deflections of a conventional crane bridge. This has a positive effect on the deformation state of the main beam and facilitates the operation of the crane as a whole.
The results obtained in this work can be further used to upgrade cranes to increase their load capacity, extend their service life without dismantling, as well as to improve existing structures and engineering calculation methods both during their design stages and under actual operating conditions.
bridge crane, load carrying capacity, previous stresses, main beams, static stiffness, deformation state.