The study presents state-of-the-art in analytical and numerical modelling of random vertical irregularities of continuously welded ballasted railway tracks. The common model of railway track irregularity vertical profiles is applied, in the form of a stationary and ergodic Gaussian process in space. Random samples of track irregularity vertical profiles are generated with the Monte-Carlo method. Based on the numerical method developed in the study, the minimum and recommended sampling number required in the random analysis of railway bridges and number of frequency increments (harmonic components) in track irregularity vertical profiles simulation are determined. The lower and upper limits of wavelengths are determined based on the literature studies. The approach yields track irregularity random samples close to reality. The track irregularity model developed in the study can be used in the dynamic analysis of railway bridge / track structure / highspeed train systems.

The homogenous properties – as flats are – have the set of key features that characterizes them. The area of a flat, the number of rooms and storey number where it is located, the technical state of a building, and the state of the vicinity of the blocks of flats assessed. The database comprises 222 flats with their transaction prices on the secondary estate market. The analysed flats are located in a certain quarter of Wrocław city in Poland. The database is large enough to apply machine learning for successful price predictions. Their close locations significantly lower the influence of clients’ assessments of the attractiveness of the location on the flat’s price. The hybrid approach is applied, where classifying precedes the solution of the regression problem. Dependently on the class of flats, the mean absolute percentage error achieved through the calculations presented in the article varies from 4,4 % to 7,8 %. In the classes of flats where the number of cases doesn’t allow for machine predicting, multivariate linear regression is applied. The reliable use of machine learning tools has proved that the automated valuation of homogenous types of properties can produce price predictions with the error low enough for real applications.

The paper focuses on the problem of optimising the cooperation between a dynamic vibration absorber (DVA) and a structure. The authors analyse a road beam bridge equipped with a working platform (deck) used to service pipelines installed on the structure. The paper studies the problem of choosing the optimal parameters for damping absorbers that reduce the random vibration of a beam subjected to a random sequence of moving forces with a constant velocity. The stochastic properties of the load are modelled by means of a filtering Poisson process. A single-degree-of-freedom (SDOF) absorber model with a multi-degree-of-freedom (MDOF) primary structure model are is considered.

Construction objects are subjected to aging processes and other changes and influences during their life cycle. The paper focuses on one of the stages of the life cycle of a developed property - the final part of the service life phase, which is referred to by the author as “the autumn years”. The paper analyses the problem of classifying a building object to an appropriate life cycle when conducting a real estate valuation. The author searched for the answers to the question of when the liquidation phase begins, because the decommissioning of a building affects the landscape and spatial heterogeneity. The reasons for demolishing buildings were analyzed, and are as follows: the poor technical condition of building objects; functional wear; difficulties in carrying out renovation or reconstruction works; and financial unprofitability, which takes into account the life phases of buildings. This paper aims to prove the following theses: - knowledge of the life cycle is the basis for the correct identification of a property’s condition, - the age of the elements of a building is not a fundamental quantity that determines the course of its physical depreciation, - the liquidation of a building has a big impact on ecological awareness.

The paper considers the problem of optimizing the absorber parameters when random vibrations of the structure create a filtered Poisson process. A new parameter optimization criterion was proposed, consisting in minimizing the probability of the maximum vibrations of the structure exceeding a certain permissible value of displacements. This criterion means maximizing the reliability of the vibrating structure with regard to the maximum vibration amplitudes.