621.177; 621.314

welded truss, temperature, metal structures, thermal effects, thermal deformations. local temperature effects, fracture mechanics.

Welded trusses are widely used in civil engineering due to the optimal combination of high manufacturability and the ability to operate in various force scenarios. During operation, such structures are exposed to a complex impact of various technological and accident factors. This makes it difficult to determine the key parameters necessary for the smooth operation of the farms during the planned period of operation. Under the simultaneous influence of force and high temperature factors on the truss structure, damage may occur in structural elements and their joints due to changes in the mechanical properties of the material, which can lead to structural failure. To identify the features of deformation and fracture of the welded truss, full-scale experimental studies were performed for the physical model at temperatures of 20°C, 200°C, and 450°C. A computer modeling experiment was also performed for similar parameters of the impact on the truss. Based on the results of the full-scale and computer modeling experiments, we generated deformation graphs that make it possible to study the strength and deformability of the loaded welded truss at fire and emergency temperatures. A series of graphical dependencies characterizing the strength and deformability of the truss when it is loaded at different temperatures has been constructed. An analytical dependence has been developed that makes it possible to determine the value of the maximum permissible load on the truss at temperatures up to 450°C based on the known value of this load for room temperature conditions with a coincidence of 97.5...98.3%. It is advisable to use the obtained dependence (graphical or analytical) when designing or operating trusses to determine the maximum permissible loads on the structure at elevated temperatures.