The intermediate principal stress (σ2 ) effect is a mechanical property inherent in many rock and soil materials. However, the effect of σ2 is often ignored in slope stability analyses, and its impact on slope stability is seldom investigated. The primary purpose of this study is to thoroughly investigate the impact of the σ2 effect on slope stability via numerical method. A detailed numerical analysis using the Finite Difference Code Fast Lagrangian Analysis of Continua (FLAC) and Unified Strength Theory (UST) is conducted. The numerical analysis evaluates the values of the Factor of Safety (FOS) for two types of slopes (plane strain and axisymmetric) using the Strength Reduction Method (SRM), and the impact of the σ2 effect on slope stability is analysed. The study found that the influence of the σ2 effect on slope stability is not sensitive to the values of friction angle φ, cohesion c, and slope height H, but increases with increasing slope angle σ values. Furthermore, the stability of the plane strain slope is more affected by the σ2 effect than the axisymmetric slope. The impact of the σ2 effect on the footing capacity and slope stability were compared, and the impact of the σ2 effect on slope stability is significantly lower than its effect on the bearing capacity of footings. The innovation of this paper is to systematically analyse the effect of σ2 on slope with different geometric shapes and soil parameters and reveal the inherent characteristics of σ2 effect on the stability of soil slope.

The problem of the concrete durability counted in tens of years is not a frequent subject of research, despite the fact that the oldest structures made with the use of Portland cement are about 140 years old, and the large size engineered constructions (like dams,breakwaters, bridges, chambers, halls) are 110 years old. The considered tank belongs to the last group of objects.In the years 1908–1909, a drinking water treatment station was built for the city of Poznan, which was then 196. 000, taking it from theWarta River. The plan dimensions are 65.5 ×21.5 m, and the height is 9.0 m above and 5.0 underground. It is a pearl of industrial architecture of the end of the 19th and the beginning of the 20th century with the most modern technological equipment in the world at that time. In the underground part, a large-size reinforced concrete tank with a ribbed ceiling supported in the middle with reinforced concrete columns was constructed throughout the projection.Those were the times when the first bold constructions from the cement concrete were built in the world, very few of which have been preserved till the present day. In order to estimate the durability of the concrete, after several decades of influence of very high relative air humidity, it is very significant to check the changes in its microstructure, which influence its strength parameters. This year the author of the project conducted a material and structural analysis of the technical condition of the over hundred ten year old tank structure, which proved that the compressive strength of the concrete is lowered, and there are numerous cracks of the walls and the ceiling, and also some accumulations of white lines and icicles outside. The SEM, EDS and XRD analyses proved that the phase composition of the concrete in the barrier thickness is variable. In the lower layers of the concrete a calcium hydroxide concentration is observed, which outside the barrier changes into the calcium carbonate. The migration of the Portlandite in the direction of the inside of the tank with very high relative air humidity (>95%) results from the mass diffusion caused by different concentration of the porous liquid in the outer and inner layers of the barriers. Those are very slow processes, that last tens of years during the exploitation of the tank. They are beneficial in terms of the gradual alkalinity increase, which protects the steel against corrosion, but they can be harmful due to a local increase of the porosity and the decrease of the concrete strength.This phenomenon has been described in the literature as elution of calcium ions from the concrete structure. Numerous articles in this field focus on creating a sufficiently durable concrete structure by dosing appropriate mineral additives, rather than on several dozen years of observations of the objects in use. Therefore, the intention of the author of this article is not to model the Ca2+ leaching process in a laboratory, but to analyze the gradual degradation of an industrial facility subjected to direct action of water over a period of one hundred years.

The intense development of urban infrastructure and the construction of deep excavations mean, that diaphragm walls are becoming one of the typical structural elements of this type of facilities, the stability of which is ensured by a system of steel struts. The paper focuses on the assessment of the value of the force in the steel tubular strut caused by the temperature difference and values of parameters necessary for proper analysis of diaphragm wall displacements. Using statistical methods to analyse more than 100,000 data from various measurements, the values of the m coefficient describing force increase in the strut at a temperature change of 1◦C were determined. The analyses allowed to determine values of the m coefficients recommended in the design of strutted diaphragm walls. These values can be used in design practice and allow to determine an additional force in the steel tubular strut due to the temperature difference.

Contemporary cities are facing the challenge of integrating public spaces, transport systems, and commercial functions, which is reflected in the revitalization processes of historic buildings. In the transformation of urban spaces, it is essential to preserve cultural heritage while respecting the historical value of architectural monuments and adapting them to contemporary needs and the principles of sustainable development. These include improving energy efficiency, employing renewable energy sources, and implementing circular economy practices. This article presents selected issues related to the comprehensive redevelopment and revitalization of the Warszawa Wileńska Railway Station – a historic facility originally constructed in 1862 as the Petersburg Station. The project, carried out under challenging conditions involving continuous passenger traffic, dense urban development, and proximity to historic tenement buildings, required the development of non-standard design, logistical, and fire safety procedures. Moreover, the construction process necessitated close cooperation with Polish State Railways (PKP) and numerous other institutions. This investment serves as an example of an innovative approach to the revitalization and integration of railway infrastructure with a multifunctional and commercially oriented shopping complex, becoming a symbol of modern revitalization efforts.

The article presents the current state of knowledge, design guidelines and principles for shaping glass load-bearing walls, which are increasingly used as structural elements in modern pavilions and public buildings. The properties of glass as a structural material are analysed, including its bending and compressive strength as well as its behaviour in a post-breakage state. Particular attention is given to glass strengthening technologies – tempering and laminating, and their impact on user safety. The article discusses the principles of designing load-bearing systems, methods of panel support, and issues related to structural stability. An analysis of fifteen pavilions from around the world that utilize glass load-bearing walls is conducted, highlighting the diversity of geometric solutions, types of glass and methods for transferring loads from the roof and wind to the supporting structure. The article also describes the draft of Eurocode 10 for the design of glass structures, which introduces consequence classes and limit state scenarios (including post-breakage phase), allowing for a comprehensive approach to the safety of load-bearing glass walls.

The article is based on data about 349 orders for road construction in Poland. The unit prices (per one kilometer of roads) are compared, arising from the following two types of orders: design-bid-build (DBB) and design & build (D&B). As the exact list of construction works, as well as, the precise number of works is unknown before the contract is signed, the contractor’s risk is higher. The probability of underpricing the offer in the case of D&B orders is higher than that of DBB orders. It is assumed that the contractors, to avoid the potential loss (if the offer is underpriced), raise the value of their offers more than in the case of DBB types of orders. This increase in offer price is usually named risk premium. The averaged unit prices of the roads of the same kind ordered as DBB are compared to D&B orders. To find the risk premium, to the values of DBB orders, the prices of the designs are added. This made the scope of the DBB and D&B orders the same i.e. able to compare. It is discovered that the average unit prices for DBB orders are higher than for D&B orders for four groups of orders, so the risk premium can’t be calculated there. For the other two groups of orders, the risk premium is 19% and 49% of the total value of the DBB order i.e. value of the design plus the value of construction works ordered.

This paper analyses the stress state in the walls of a closed steel profile caused by freezing water filling the interior of the profile. The study focuses on a specific case of two damaged girders, where the failure was attributed to freezing water trapped inside the upper chords of the girders. The analysis revealed that the resulting stresses exceeded the steel’s strength, leading to deformation and rupture of the upper chord profiles. The article describes the damage observed in the girders, including outward deformation of the walls and cracks along the bending edge. The presence of water and corrosion products inside the profiles was confirmed through inspections. Finite element calculations were performed to assess the pressure effects, showing that the tensile stresses in the corner of the profile exceeded the yield and tensile strength of the steel. The article concludes that damage caused by freezing water expansion is unpredictable and emphasises the importance of weld quality control in steel structures.

In this paper, four feasible closing schemes are proposed, three of which are optimization schemes, and the deformation and internal force of the main beam are taken as the control elements, and the closing conditions, cumulative vertical displacement, lower and lower edge stress on the cross-section and horizontal displacement of the support are compared and analysed under different closure sequence schemes. It is found that the displacement and stress differences are large in different closure sequence schemes, different structural system conversion timings, and it is necessary to carry out optimization studies and comprehensively compare and select reasonable schemes. The construction control of the closure stage is studied, and the results of bridge construction control are compared, which shows that the optimization technology and construction control technology of the closure sequence can be used in this paper, which can solve the key problems in the construction control of the closure of long-link continuous beam bridges, and can provide reference and basis for the construction control of the same type of bridge.

As part of the research, concrete mixes containing the addition of bottom ash as well as bottom and fly ash mixtures from the combustion of biomass only were made. The ashes were obtained from the combustion of 80% of wood and 20% of sunflower in a fluidized bed boiler. In the study, the elemental composition of ashes was determined by testing with an XRF X-ray spectrometer. Ashes in the amount of 10, 20 and 30% of the cement mass were used as a substitute for sand for testing concrete samples. During the preparation of concrete mixes, tests of consistency and air content in the mixes were carried out. Concrete samples were tested in terms of e.g. compressive strength, water absorption or frost resistance. The compressive strength of the samples with the addition of bottom ash was lower than the strength of the control samples. The use of a mixture of ashes allowed to improve this property and each of the samples obtained a higher compressive strength than samples without the addition of ash. The addition of ashes significantly improves the frost resistance of concrete, i.e. reduces the decrease in the compressive strength of concrete after frost resistance tests. The absorbability of the samples, regardless of the amount and type of added ash, changed slightly in relation to the control samples.

The paper presents analyses aimed at determining how the spacing between legs of a steel lattice telecommunication tower affects displacements of its top, its natural frequency, and its self-weight. The critical characteristic of the results is that they were obtained for structures optimized with respect to the load-carrying capacity of their individual components. It was assumed that levels of effort should be kept between 85% and 95%. As far as engineering practice is concerned, the key conclusion is that a larger distance between the legs has a positive impact on the self-weight of the structure. It was demonstrated that a larger leg spacing is related to a smaller self-weight of the tower and thus a smaller quantity of material required. The proposed research and calculation method makes it possible to conclude that providing a larger distance between the legs while optimizing structural members with respect to their effort (preferably by means of an automated process) results in both higher bending stiffness and lower structure self-weight required.