Technological features of metal structures strengthening by gluing of high-strength FRP-systems during reconstruction

The building heritage of Ukraine includes numerous examples of metal structures, especially used in industrial buildings and for large-span structures. The use of metal structures in construction is primarily due to their mechanical properties. They are frost-resistant and can withstand temperatures down to -65 degrees, tough, resistant, durable and reliable. They can also be used in areas with increased seismic activity. But, in certain situations metal structures need to restore or strengthen due to structural defects, wear of load-bearing elements, as well as in order to increase the bearing capacity. In some cases, strengthening with fiber-reinforced polymer composites (FRP) gives better results than traditional methods with metal strengthening. A significant part of the Ukrainian architectural and historical heritage is made up of buildings and structures using metal structures. The first designs were made of cast iron or wrought iron (machined or tinned), but they subsequently developed rapidly along with the evolution of methods for forging mineral iron. The main cultural reason for the restoration of old metal structures that guarantee structural functionality and load-bearing capacity, based not only on the need to preserve their historical origin, but also on the value of the landscape in which they are located. Long-term operation of buildings and their structural elements made of metal without timely maintenance and major repairs, insufficient strength of structural materials, as well as changes in weather conditions and current regulatory documents in Ukraine, often leads to the need to recalculate the load-bearing metal structures of the building frame and strengthen them with the most effective methods, both from the point of view of reliability and from the point of view of profitability, which is influenced by prolonged shutdown of enterprises, stoppage of the production process or the inability to use the adjacent territory to carry out reconstruction work. The article discusses the technological features of metal structures strengthening by gluing high-strength FRP-systems during the reconstruction of building, and also provides basic recommendations for the installation, monitoring and maintenance of strengthened elements.