Structure and Properties of the Steels of Hyperboloid Gridshell shukhov’s Towers After Long-Term Operation

We study the chemical composition, structure, hardness, corrosion resistance, and electrochemical prop- erties of the metal of authentic and repair structural elements of water towers in the cities of Mykolaiv and Cherkasy and also of the Adziogol lighthouse built at the beginning of the 20th century according to the projects of V. G. Shukhov. We analyze possible causes of fracture of the repair welded joints of steels produced by using different technologies and the influence of the composition of corrosive medi- um and testing temperature on the corrosion-electrochemical properties of authentic steels. It is shown that the metal of the Adziogol lighthouse has the lowest corrosion resistance, which is obviously con- nected with the effect of long-term hydrogenation in more corrosive (chloride-containing) media. At present, the problem of preservation of old-time metal structures attracts strong attention of the world scientific community. This includes the diagnostics of the engineering state of structural elements aimed at the detection of defects and the analysis of the characteristics of the metals, which deteriorate in the process of oper- ation and may fail to meet the requirements to the structural strength of the investigated objects. Thus, for this purpose, the researchers study the physicomechanical properties of the steels of bridges and viaducts built in the 18th and 19th centuries (1-3) and, on this basis, predict their residual service life. In Ukraine, much attention is given to the engineering structures in the form of hyperboloid gridshell towers built at the beginning of the 20th century according to the projects of V. G. Shukhov (4, 5). For the same bear- ing capacity, the amount of metal used for their construction is three times lower than the amount of metal used in the other similar structures of that time. As examples of Shukhov's structures, we can mainly mention operat- ing lighthouses in the Dnieper mouth and water towers, which should necessarily be preserved as monuments of industrial architecture, although they are no longer used in the systems of water supply. The main structural elements of Shukhov's towers are angles made of low-carbon steel sensitive to atmos- pheric corrosion. In the course of erection works, separate elements of the towers were joined only by rivets. In the course of long-term operation, the metal of angles and riveted joints suffered noticeable corrosion damag- es of different types and intensities. To guarantee the required serviceability and maintain the appropriate engi- neering state of these structures, they were repaired with the use of newer types of metals and the technologies of welding typical of the time of repair.