Introduction. Due to the constant increase in design-exceeding technogenic and natural impacts on buildings and structures, an important direction for improving their safety is to conduct experimental research on structural elements designed to protect against such impacts. The most critical components of these structural systems are the connection joints between their elements, which must ensure the safety of the frames under various, including extreme, conditions. This necessitates a more comprehensive assessment of their crack resistance under special impacts.

Materials and methods. The experimental study was conducted on a specially designed test setup capable of simulating the stress-strain state of a beam both under service conditions and under emergency impacts. During the test, at various stages of loading with the design load and after the emergency impact, the following parameters were measured: strains in the concrete and reinforcement, vertical and horizontal displacements of the joint elements. The pattern of crack formation, propagation, and width was also recorded.

Results. A study was conducted on the connection joints of heavy concrete bar elements under static and static-dynamic loading. The results of experimental investigations into crack resistance, as well as the development, width, and patterns of crack formation in the connection nodes under these loading conditions, are presented.

Conclusions. The study results indicated a similar pattern of crack formation in the connection joints of beams and columns under both static and static-dynamic loading. A difference was observed in the location of flexural cracks in the columns, which is explained by the multi-stage nature and the time interval of the static load application.