Experimental research on concrete deformation during unloading at a descending section and reloading

The results are presented for the experimental research on concrete, loaded to the formation of a descending section on the stress-strain diagram, unloading from the descending section, and subsequent reloading. The tests have been conducted on a special device, simulating a one-time statically indeterminate structural system. The factors influencing the formation of unloading and reloading diagrams are determined. Also, empirical dependencies have been given, using which it s possible to make calculations of structural systems when unloading zones are observed. This happens when systems are not repeatedly reloaded and in cases of local damage occurring for various reasons. The necessity for such studies is substantiated.