Paper describes in detail and gives example of the probabilistic assessment of a steel structural element subject to fatigue load, particular attention being paid to cracks from the edge and those from surface. Fatigue crack damage depends on a number of stress range cycles. Three sizes are important for the characteristics of the propagation of fatigue cracks - the initial size, detectable size and acceptable size. The theoretical model of fatigue crack progression in paper is based on a linear fracture mechanics. When determining the required degree of reliability, it is possible to specify the time of the first inspection of the construction which will focus on the fatigue damage. Using a conditional probability, times for subsequent inspections can be determined. For probabilistic calculation of fatigue crack progression was used the original and new probabilistic methods - the Direct Optimized Probabilistic Calculation (“DOProC”), which is based on optimized numerical integration. The algorithm of the probabilistic calculation was applied in the FCProbCalc code (“Fatigue Crack Probabilistic Calculation”), using which is possible to carry out the probabilistic modelling of propagation of fatigue cracks in a user friendly environment very effectively.

The results of numerical calculations on the resistance of the reinforced concrete bridge deck to chlorides are compared with a different approach to the diffusion coefficient of the input parameter, and presented. The aim is to point out the necessity of a correct model adjustment in the case of using diffusion parameters obtained differently at different measurement times. The diffusion parameter, as a typical concrete material constant, was derived from electrical resistivity measurements and using the least-squares method from a direct chloride test. Due to the different times of obtaining the concrete parameters, a control calculation was performed, which showed that the numerical model for calculating the initiation of reinforcement corrosion in chloride-exposed reinforced concrete requires the application of not only a suitable diffusion parameter but also an adequate reference time. The article points out the need to use an adequate reference time introduced in the numerical calculation of the durability of reinforced concrete with respect to aggressive substances. The results show that the most appropriate reference time value is derived from the average measurement time related to the lifetime of the concrete.

The closed steel supports of different shapes are used in mining and underground constructions. The yielding and unyielding supports are prefabricated from rolled, usually robust steel profiles. The load carrying capacity of the support is considerably influenced by the active loading and passive forces. The passive forces are induced by the interactions of support with the surrounding rock massif [1]. The user-friendly software was processed for the operational determination of load carrying capacity. The analysis has three parts: the first part consists of the structural geometry processing. The second part includes the numerical solution of statically indeterminate structure for the specified load. The third part is the calculation of load carrying capacity, components of internal forces and deformations. The force method and the numerical integration were used for solution. The Winkler model is applied when the support is in interaction with the surrounding environment. The load carrying capacity of support is limited by the slip resistance of the connected parts and reaching the ultimate state of the profile. The plasticity calculation is performed in accordance with EN 1993-1-1 Ed. 2. The limit values beyond the scope of this standard can be selected for an alternative computation.

The paper deals with the calculation of the load carrying capacity of the steel arch reinforcements of underground and mine works with respect to the resulting large displacement and physical nonlinearities. Solution is based on the application of the so-called effective bending stiffness, which is defined as a function of the axial force and bending moment. The numerical model was verified using the values of the load carrying capacity, which have been experimentally obtained using strain-stress test, and implemented into the software that allows very effectively calculate load carrying capacity of steel arch reinforcements.

The degradation of reinforced concrete (RC) in aggressive environments is caused by a combination of factors ranging from force loading to weathering, to various chemical agents. Reinforcement corrosion in RC structures caused by excessive chloride ion diffusion is then one of the highly critical factors related to the potential destruction of this construction. Considering these facts, it is highly desirable to investigate the behaviour of concretes under a combination of force and chemical loading. The present study thus provides the basic results of an experiment in which laboratory concrete specimens were first subjected to partial loading in a press machine, then immersed in a fully saturated salt solution, and in the last step the compressive strength was determined. The loaded specimens were compared with specimens without the first loading and also with specimens immersed in normal water. This makes it possible to evaluate the combined effect. The results were evaluated also with respect to the strength increase under maturation of concrete in time. The results showed that concrete immersed in water after initial partial loading has a lower ultimate strength. Then, concrete without preloading force but immersed in chloride solution showed lower values and concrete preloaded and immersed in chloride for 90 days had the worst residual strength result.