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Abstract

Concrete structures that are influenced by degradation, overloading, the thawing, and freezing cycles, corrosion of reinforced bars, should be repaired or strengthened. Each of the mentioned influences lead to decreased load-carrying capacity of the structure or its member. Exceeding the load-carrying capacity leads to mechanical damage of members or excessive deformation. The damaged member has to be strengthened to the required level of reliability and load-carrying capacity. There exist many types and methods of strengthening the columns. This research work deals with strengthening of columns by concreting a new layer of fiber concrete. When applying that type of strengthening, it is necessary to assure the contact between the old layer and the new one. The paper deals with analysis of different types of contacts and determination of their parametric values.

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Pollack Periodica
Authors: Stepan Shapoval, Nadiia Spodyniuk, Vasyl Zhelykh, Volodymyr Shepitchak, and Pavlo Shapoval

Abstract

In line with the energy development strategy of Europe, it is necessary to implement energy efficient buildings, in which the external enclosures are converters of solar energy to thermal. Therefore, the purpose of the publication was the scientific substantiation and development of the solar heating system with the use of rooftop solar panels. Graphical and analytical dependences of the coefficient of thermal efficiency of the solar panel in heat supply system from the angles of solar radiation incoming and the density of the radiation flux were obtained. Analysis of the results showed that the coefficient of thermal efficiency of the solar panel without transparent coating with the placement of pipelines of the circulation circuit of the coolant over the heat absorber increases by 50%.

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Abstract

Safety valves are the most important safety devices of the pressure system. For safety valves in the vast majority of cases in industrial environment, direct spring-loaded safety valves are used. The most important parameter of the equation of motion is the flow force. The main goal of the analysis was to compare the simulated flow forces with the measured results and validating the computational fluid dynamics model. Simulations were made in ANSYS 2019 R1 code for numerous fixed valve disk positions on different pressures. Results are in good agreement with the measured data.

Open access

Abstract

Concrete indeterminate flexural members represented by continuous beams reinforced with both fiber-reinforced polymers and steel bars in a way that allows for moment redistribution at failure are analyzed. The efficiency of introducing steel bars in the critical sections where plastic hinges are likely to form is evaluated in terms of reliability. Monte Carlo simulation and the concept of comparative reliability are both employed. Ultimately, the effect of different design parameters on the strength reduction factor is evaluated.

Open access

Abstract

The aim of this paper is to introduce the visual elements that may influence the lighting quality, and link them with the functioning of drug addiction institutes to understand the adequate design for each function and assure the well-being of the patient, therefore reduce their stress. The suggested strategy accords the qualitative and quantitative lighting design conditions to afford a complete reference for the forward study.

Open access

Abstract

With the continuous development of society and cities, people’s demand for urban public space is constantly changing, and the methods for public space renewal are becoming more and more diverse. As a flexible space renewal strategy, street art activities can not only partially update the space, increase the vitality of the space, but also improve the quality of the space and meet people’s needs. This paper first discusses the concepts and types of street art and clarifies the scope of research, Then, through the analysis of the role and impact of “street art activities intervening in urban space”, and finally summing up the relevant enlightenment, to create a favorable material environment for the future art intervention space.

Open access

Abstract

Castellated beams are made from a hot rolled steel I-section in a few steps. Firstly, the web of the parent I-section is cut in a particular zigzag pattern and the two halves are reconnected by welding to form a castellated beam with hexagonal openings. In other cases, a spacer plate is placed between the two halves to produce octagonal openings, which increase the section depth. Increasing the depth by adding spacer plates leads to web-post buckling. This study focuses on improving the castellated beam to obtain high strength with relatively low cost by placing a steel ring inside the octagonal openings to strengthen the weakest part, which is its web. The results show that the steel ring is effective in strengthening the web-post.

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Abstract

Cold asphalt emulsion mixtures are produced at ambient temperature and it have several advantages i.e., energy savings, safety and reducing CO2 emission during manufacturing and construction, reduction of adverse environmental impact. Cement kiln dust is a fine powdery substance with appearance similar to Portland cement that is generated as a by-product material of cement manufacturing industry. The aim of this research is addition of cement kiln dust instead of Portland cement as filler in asphalt emulsion mixtures. Cement kiln dust was added with 2, 4, 6, and 8% from total weight of aggregate to improve the mechanical properties and durability of this mixture. The results were very positive and encouraging, due to the improvement of the mechanical properties and durability of the mixtures.

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Pollack Periodica
Authors: Ivan Baláž, Yvonna Koleková, Lydia Moroczová, and Antonio Agüero

Abstract

Eurocodes give guidance how to design built-up columns having effective bending stiffness, smeared shear stiffness and local bow imperfection amplitude e 0 = L/500 under compression. The guidance is valid only for columns supported by hinges at their ends. The second order theory is presented, which allows analysis of the battened and laced built-up columns with initial imperfection under combined compression and bending with the bottom end fixed and the upper one free in the case of in-plane buckling. The application of the theory in several numerical examples is given in Part II.

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Abstract

The congested traffic flow is significantly different from both the free flow and the non-congested but limited flow. Two of those differences are in the merging and crossing movements. Based on the conducted measurements, this movement could be up to 10 times faster in the congested condition. Another important feature is the giveway gestures. It was found that the vast majority of the gaps needed to merge or cross are not generated by the traffic dynamic, but created by the arterial road's drivers in the interactions with drivers wishing to merge or cross.

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