In a paper are considered four existing analytical methods for determination a bearing capacity of concrete-filled tubes structures under axial compression. Analyzed approaches to the questions of a limit compression load calculation are able to withstand a composite element. Highlighted the fundamental features and similarities of discussed methods, and also their shortcomings affecting to the accuracy of the strength and stability computing results. On the particular example performed a results comparison of determination the bearing capacity by the four methods.

An article compares the theoretical and experimental researches of joint work of steel tower type supports' fragments of overhead power transmission lines (OHPL) 110 kV. Attention is focused to high voltage supports operated on the Ukraine territory. Is described a spending principle of static experimental researches for flat trusses on the developed specialized experimental installation, allowing to investigate the joint work of overhead lines supports' fragments. Are presented the technique and results of the flat support model calculation in the "SCAD" software package. Are presented calculation numerical results of the experimental installation together with a testing model. Are determinated experimental values of stresses in lattice elements and also horizontal and vertical displacements of braces holding on nodes. During the displacements determining is analyzed the joint work of the lattice elements of the experimental samples, is taken into account the supporting effect of the extended braces.

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Abstract. The article presents a new concept of design of power lines which allowed us to develop new unified power transmission supports, efficient and reliable ones. For the first time, a method of optimum design of overhead power lines has been developed which considered the power line as a united structural system, the relief, the atmospheric and climatic conditions, the environment pollution, the efficiency requirements, the technological and operational expenditures. The article describes the changes introduced into the requirements for the dimensions and parameters of grid metal works with the minimum mass. The optimum design, the computer-aided assembly process and the use of advanced technologies guarantee the reduction of the construction period and the increase in the maintenance period of power lines.