In the paper, experimental studies of the hydrogen and pre-strained effect on fracture resistance of steam generator steel 22K were carried out. Special cylindrical samples were loaded up to fracture under a uniaxial tensile test with different pre-strained degrees and hydrogen charged times of the material. Stress-strain curves «S_i–e_i» were plotted. The true strain «e_i» in the local volume was determined using the method of optical-digital image correlation (ODIC). The results showed that the hydrogen influence is practically absent in the elastic area of strain. The fracture energy of steel 22K decreases under the hydrogen influence and pre-strain in all investigated cases. It is shown that during six months of air exposure, with the 0% pre-strained samples release almost all hydrogen. In pre-strained samples, the hydrogen concentration decreased by 1–3% compared to the initial values. This indicates that they have trapped hydrogen that cannot escape on its own. Hydrogen embrittlement (HE) indexes for 0% pre-strained samples at different levels of hydrogen-charging calculated by the strain and energy approaches are equal to each other. There is a difference in the values of the HE index depending on the hydrogen-charge time for pre-strained samples. This indicates that both strain and strength characteristics of the material, which are integrally taken into account in the energy approach, are sensitive to HE.

A methodology for determining the technical state of reinforced concrete bridge structures has been developed. It is based on establishing the depth and location of the largest deflec­tion using a laser projection system, as well as an approach to finding the stress-strain state along the height of the beam. For this, an energy approach is used, which involves the cal­culation of the energy of elastic-plastic deformation of concrete and reinforcement. The specific fracture energy as an invariant characteristic of concrete strength under tension, compression, and also tension of reinforcement have been established experimentally. A method of constructing true diagrams of deformation and fracture of concrete samples taken from the structure has been created. The results of experimental studies of the stress-strain state during bending of a reinforced concrete beam agree well with those calculated by the finite element method.

The results of experiments studying the contact angle dependence for different initial gaps at a pin joint under loading are presented. Considering the change of the interacting sur­face area of the composite plates with a pin, the bearing capacity of the hole is deter­mined. The modified correlation algorithm for digital image processing is used to obtain the experimental results.