W artykule przedstawiono badania nieukończonych i czasowo nieużytkowanych budynków wielkopłytowych przeprowadzone w celu oceny ich stanu technicznego. Wykorzystanie specjalistycznej aparatury do badań nieniszczących umożliwia ograniczenie liczby badań niszczących. Właściwe opracowanie metody badań oraz określenie metod pozyskiwania miarodajnych wyników skutkuje wiarygodną oceną stanu technicznego budynków.

The conception of special finite elements called multi-area elements for the analysis of structures with different stiffness areas has been presented in the paper. A new type of finite element has been determined in order to perform analyses and calculations of heterogeneous, multi-coherent, and layered structures using fewer finite elements and it provides proper accuracy of the results. The main advantage of the presented special multi-area elements is the possibility that areas of the structure with different stiffness and geometrical parameters can be described by single element integrated in subdivisions (sub-areas). The formulation of such elements has been presented with the example of one-dimensional elements. The main idea of developed elements is the assumption that the deformation field inside the element is dependent on its geometry and stiffness distribution. The deformation field can be changed and adjusted during the calculation process that is why such elements can be treated as self-adaptive. The application of the self-adaptation method on strain field should simplify the analysis of complex non-linear problems and increase their accuracy. In order to confirm the correctness of the established assumptions, comparative analyses have been carried out and potential areas of application have been indicated.

The paper presents an innovative matrix method for defect analysis in heterogeneous structures with significant differences in stiffness parameters. The proposed approach modifies the finite element method (FEM) by introducing a refined type of finite element capable of handling regions with varying material and geometrical properties. Unlike traditional FEM discretization, which increases computational time calculations due to mesh refinement in stiffness-variable areas, the proposed method maintains a consistent discretization while adjusting shape functions to reflect internal stiffness changes. An original functional for modifying linear shape function distributions is introduced, leading to piecewise broken-line shape functions. This enhancement significantly improves the accuracy of numerical calculations, as verified by computational calculations. The explicit formulation of the stiffness matrix enhances computational efficiency, making the approach particularly useful for periodic structures with inclusions, voids, or localized material defects. The results of numerical tests demonstrate that the proposed method provides solutions closely aligned with conventional FEM results while substantially reducing computational costs. The approach is particularly relevant for structural engineering applications where defect analysis and material heterogeneity play a critical role in design and safety evaluation.

Climate change increasingly affects the sustainability and reliability of urban water and wastewater infrastructure. This study analyzes the relationship between climatic variables and the frequency of failures in water and sewage networks in northeastern Poland, using operational data from the Mrągowo system (2020–2023) and meteorological records from 1966 to 2023. Statistical analyses and trend assessments were employed to identify climate-related failure patterns and infrastructure vulnerabilities. Climatic parameters—including temperature extremes, precipitation, snow cover, and sunshine duration—were analyzed in relation to infrastructure reliability. The results indicate rising temperatures, reduced snowfall, and altered precipitation regimes. Although extreme cold corresponded with increased sewage network failures, no significant association was found for high temperatures. Precipitation and snow cover showed weak correlations, except during heavy rainfall events. The study highlights the need to integrate climate resilience into water infrastructure management through preventive maintenance, smart monitoring, and nature-based solutions. Findings contribute to sustainable urban development strategies by demonstrating how climate variability directly affects service reliability. By identifying climate-sensitive failure thresholds, the study supports sustainable infrastructure management by enabling risk-informed adaptation strategies that reduce service disruptions, resource losses, and environmental impacts. This case study offers methodological insights and empirical evidence that may support the assessment of climate-related vulnerability of water and wastewater infrastructure in similar urban contexts.