| Abstrakt: |
When carrying out installation work at the enterprises of the branch, the use of universal lifting equipment is sometimes impossible or impractical. In such cases, resort to the use of mounting masts - relatively simple in design and quite efficient lifting equipment [1], the construction of which is largely based on the practical experience of foremen of assembly organizations or foremen- riggers. Existing methods of calculation of mounting masts, developed many decades ago on the basis of sufficiently primitive considerations, without taking into account additional loads, give approximate results and should be revised and improved. An attempt at such work is reflected in this article. Since the main structural elements of the mounting mast are its riser and cables, the definition of the parameters of the mast is to calculate the strength of the riser and cables of the accepted dimensions under the loads provided by the initial data of a specific technical task. Evaluation of the strength of the riser should be performed both in the plane of torque and from the plane of torque. To find the value of the maximum stress in the mast riser and the maximum stress in the i-th cable, it is necessary to calculate the stress-strain state of the riser and cables using a mixed method, according to which some unknowns are displacement and part - effort. The mathematical model of the problem is described by four algebraic equations. The equation of continuity of riser deformations is based on the use of Tymoshenko's functions, which take into account the influence of longitudinal forces on the deflection of the mast riser in the plane of action of wind load and weight of cargo. Loads from the weight and tension of the cables are taken into account their possible ice and the force of pre-tension. The wind load of the riser and cables is determined using data on the standard speed pressure, N / m2, which for Ukraine is 0.38 kPa. Calculations of riser and cable parameters also take into account the temperature difference, which in the climatic conditions of Ukraine does not exceed the interval ±40 0С. Mast structures are recommended to rely on the combination of both permanent and temporary loads according to the data given in the article. All this together gives reason to hope that the considered method of calculation of parameters of assembly masts will be useful to experts of the assembly organizations and students studying questions of technics and technology of rigging works. [ABSTRACT FROM AUTHOR] |
