Reliability is one of the most significant requirements for structures given in Eurocodes. Thus, the specific level of safety, serviceability, and durability have to be satisfied to fulfill the reliability of structures. In the case of reinforced concrete (RC) members, the corrosion of reinforcement is not assumed in the stage of structure design, which is in contrast with the structures in service, where the corrosion of reinforcement can significantly decrease their diameter ø in time. In these cases, the moment resistance in time M_Rd(t) decreases during the designed lifetime T_d of a structure. The corrosion speed is as a basis for the calculation of moment resistance in time M_Rd(t), i.e., a first-year corrosion rate r_corr and a corrosion model as well. The corrosion itself is a very complicated issue, so the first-year corrosion rate r_corr and also the corrosion model can be different under various conditions in Slovakia. The paper is focused not only to determine the corrosion speed (first-year corrosion rate r_corr and the corrosion model) and parametric study of the moment resistance in time M_Rd(t) under various conditions in Slovakia but also shows an overview on some parameters that may influence the corrosion process.

In the case of prestressed concrete structures, information about the actual state of prestressing is an important basis for determining their load-carrying capacity as well as remaining service life. During the service life of the prestressed concrete structure, the initial level of prestressing is inevitably reduced as a result of the actions of various factors. These reductions of prestressing force are considered as prestress losses, which are influenced by construction stages, used materials, prestressing technology, or required length of service life. Available standards enable the determination of the expected values of prestress losses. Ultimately, their calculation is part of the design procedure of every prestressed concrete structure. However, aging and often neglected infrastructure in Europe is also exposed to factors, such as environmental distress, that are not considered in standard calculations. Therefore, verified and reliable methods for determining the actual state of prestressing are needed. This paper presents an experimental program of an indirect method for the evaluation of the value of prestressing force in seven prestressed concrete sleepers. Particularly, the non-destructive saw-cut method as a pivotal object of this study is performed and assessed. Furthermore, the Barkhausen noise technique is used as a comparative method. Subsequently, the experimental campaign is supported by the numerical analysis performed in the ATENA 3D software. Finally, the experimentally determined values of residual prestressing force are compared to the expected level of prestressing according to Eurocodes.

Ageing infrastructure leads to the need for a proper assessment and final decisions considering its state. In the case of prestressed concrete structures, knowledge of the residual state of prestressing is the crucial factor. Therefore, reliable diagnostic techniques for determining the residual value of the prestressing force are needed. This information is subsequently used in the process of the quantification of the load-carrying capacity and remaining service life of prestressed concrete structures. The presented paper introduces an evaluation of a monolithic 62-year-old prestressed concrete bridge, which was built in 1959. The assessment was carried out as a result of concerns after exposure of the anchorage area of the bridge, which was executed during the construction of the new system of anti-flood barriers in the town of Banska Bystrica in central Slovakia. Therefore, the diagnostic survey and subsequent determination of the residual prestressing force included the application of the saw-cut method, the structural response method, and the Barkhausen noise technique. Finally, the experimental program supported by numerical analysis provided information about the actual state of prestressing in the bridge. Results of performed analysis suggested that the state of prestressing of the bridge in question does not significantly differ from the expected level of prestressing after 62 years of service. Subsequently, obtained conclusions enabled the determination of the load-carrying capacity for future use in the form of a pedestrian bridge.

These elements are innovative and of interest to many researchers for the reinforcement of wooden elements. For the reinforced beam elements, the effect of the reinforcement factor, FRP and steel elastic modulus or FRP and steel arrangement of the reinforcement on the performance of the flexural elements was determined, followed by reading the load-displacement diagram of the reinforced beam elements. The finite element model was then developed and verified with the experimental results, which was mainly related to the fact that the general theory took into account the typical tensile failure mode, which can be used to predict the flexural strength of reinforced timber beams. From the tests, it was determined that reinforced timber beam elements had relatively ductile flexural strengths up to brittle tension for unreinforced elements. As for the reinforcements of FRP, the highest increase in load-bearing capacity was for carbon mats at 52.47%, with a reinforcement grade of 0.43%, while the lowest was for glass mats at 16.62% with a reinforcement grade of 0.22%. Basalt bars achieved the highest stiffness, followed by glass mats. Taking into account all the reinforcements used, the highest stiffness was demonstrated by the tests of the effectiveness of the reinforcement using 3 mm thick steel plates. For this configuration with a reinforcement percentage of 10%, this increase in load capacity was 79.48% and stiffness was 31.08%. The difference between the experimental and numerical results was within 3.62–27.36%, respectively.

Components of civil buildings are frequently made of low-alloyed steel, which can suffer from corrosion damage. This damage reduces their bearing capacity and/or redistributes the load to neighboring regions with the potential risk of their collapse. For this reason, this study deals with the non-destructive monitoring of bodies made of these steels based on Barkhausen noise emission. The superimposing contribution of corrosion extent and exerted tensile load is investigated on samples of variable yield strength in the range from 235 to 1100 MPa. It is found that the presence of a corroded layer attenuates Barkhausen noise and makes the body harder from a magnetic point of view. The reduced effective thickness of the samples as a result of corrosion damage increases the true stress. Barkhausen noise grows along with the tensile stress in the direction of exerted stress at the expense of decreasing Barkhausen noise in the perpendicular direction. The evolution of Barkhausen noise versus tensile stress is mostly shifted to the lower values of Barkhausen noise, along with the increasing degree of corrosion damage. The evolution of Barkhausen noise versus tensile stress is also affected by the initial microstructure and the corresponding yield strength of the low-alloyed steel. Corrosion attack results in the growth of FWHM, which is compensated by the decreasing evolution along with the tensile stresses. The effective values drop down with the higher extent of corrosion damage. However, the response with respect to the tensile stress is asymmetric in RD and TD due to the realignment of DWs into RD. Finally, PP tends to increase with the corrosion attack as well as the tensile stress and this parameter only exhibits the systematic behavior in RD as well as TD. On the other hand, MBN-extracted parameters as well as their combination provide no exclusive values on which the pure contribution of corrosion and tensile stress can be distinguished.

Reinforced concrete (RC) structures are basically composite elements because they consist of two materials—concrete and reinforcement (reinforcing steel bars). From the point of view of the design of new constructions, it is necessary to design them in such a way as to ensure their reliability, safety and durability throughout their design lifetime, T_d. However, all elements, including RC members, are affected by the environment in which they are located. An aggressive environment causes degradation of materials. In the case of reinforcement, corrosion of the reinforcement is considered to be the most well-known and at the same time the most serious way of degradation. From the point of view of existing reinforced concrete elements, it is therefore important to know whether and how the corrosion of the reinforcement affects the mechanical properties of the given reinforcement. The mechanical properties of reinforcement are very important when assessing the actual condition of reinforced concrete (RC) elements, to determine the resistance and load-carrying capacity of the elements. Therefore, it is necessary to investigate the effect of corrosion on mechanical properties of reinforcement. The paper reports on the results of an experimental analysis of the effect of corrosion on the change in the mechanical properties of reinforcement. Furthermore, it presents both the redistribution of mechanical properties along the cross-section of reinforcement, produced by various techniques, such as hot-rolling, hot-rolling with controlled cooling from rerolling temperature and cold-rolled as well as the mechanical properties under the action of corrosion.