rss_2.0Slovak Journal of Civil Engineering FeedSciendo RSS Feed for Slovak Journal of Civil Engineering Journal of Civil Engineering Feed Simplified Approach for the Evaluation of the Non-Visual Potential of Daylight in Side-Lit Rooms<abstract><title style='display:none'>Abstract</title> <p>This article reports on the development, validation, workflow and implementation of a simplified method for evaluating the non-visual (melanopic) potential of daylight in typical side-lit rooms. The method is suitable for climatic areas with a dominant occurrence of cloudy skies. The non-visual daylight evaluation tool is based on a modified average daylight factor method. A simplified daylighting model improves the calculation of the vertical daylight factor and the passage of daylight through a vertical lighting opening. The proposed calculation method makes it possible to determine the illuminance of a vertical plane in the interior. The method is based on the uniform sky and the external diffuse horizontal illuminance at the location of interest. The outputs of the tool can also be used to quickly estimate visual levels of daylight. The article also proposes a classification of the availability of melanopic daylight in side-lit rooms, which is based on the outputs of the proposed calculation method.</p> </abstract>ARTICLEtrue of Hypoplastic Parameters for Danube Sand<abstract><title style='display:none'>Abstract</title> <p>The relationship between stress and strain tensors in soil is described by the soil constitutive equation, which depends on the soil type and deformation conditions. The development of various constitutive models has enabled a better understanding of the macromechanical properties of soil. One such model is hypoplasticity, which was discovered more than three decades ago. The purpose of this study is to determine whether hypoplasticity could accurately represent the behavior of Danube sand, a specific type of sand. The researchers conducted laboratory measurements to obtain the eight basic hypoplastic parameters of Danube sand and employed the intergranular strain concept as an extension of hypoplasticity to achieve a more precise material behavior. All the parameters were then utilized to simulate the cyclic triaxial test using the SoilTest Module of PLAXIS. The results showed that the hypoplastic constitutive simulation model for Danube sand was capable of making relatively accurate predictions for accumulative settlement.</p> </abstract>ARTICLEtrue Relative Success in Obtaining Grants for Smart Cities in the European Union and on the Cost of the Outcome<abstract><title style='display:none'>Abstract</title> <p>The concept of smart cities is gaining momentum with efforts to go greener and be more sustainable along with the growing demand for data-driven policies. The European Union (EU) is highly committed to fostering sustainable urban development through targeted funding programs that encourage innovation, collaboration, and practical solutions for climate-neutral and smart cities. We have used data mining on the data of the Community Research and Development Information Service (CORDIS) and Eurostat during 2014 – 2022, to analyze such projects. Firstly, we can report that in absolute measures, Germany, Spain, France, Sweden and Lithuania have obtained the largest amounts of money fromthe EU Horizon program to support the development of smart cities. Secondly, we have found that when accounting for the size of funding per capita, Estonia leads in terms of funds invested in smart cities followed by Luxembourg, the Netherlands, Finland, and Cyprus. Focusing our attention on the cost of outcomes, i.e., the efficiency of spending funds on smart cities, we can see that the leading countries in the EU are Romania, Switzerland, Norway, and Luxembourg. The authors have compared the success of European projects in their different phases, while considering the overall results as most relevant for our evaluation.</p> </abstract>ARTICLEtrue Effect of the Development of Bicycle Transport from the Point of View of the Inhabitants of the City of Bratislava<abstract><title style='display:none'>Abstract</title> <p>As part of a change in the division of transport work, bicycle transport has made the most progress in recent years. As the largest city in Slovakia Bratislava, is trying to keep up with foreign cities. In recent years, it has developed projects that have made it possible to increase the development of cycling in the city. The last major cycling survey was conducted in 2011 by Cyklokoalicia. This survey aims at determining the momentum of bicycle traffic by identifying its greatest shortcomings or, conversely, the most positives. The data from the analysis given will also be used to develop a concept for the development of bicycle transport in the city of Bratislava.</p> </abstract>ARTICLEtrue of Strapping Straps Waste Fibers on Fresh and Hardened Properties of Concrete<abstract> <title style='display:none'>Abstract</title> <p>Faced with the increasingly growing need for construction material resources and the strict requirements and conditions for preserving the environment, it has become necessary and relevant to study all possibilities and opportunities for the recycling and valorization of industrial waste and by-products in the construction field. Strapping straps is a product used to bundle and transport goods and construction materials. After its use, it is considered as waste. The objective of this experimental work is to study the possibility of reusing the strapping strap waste as fibers in the production of fiber-reinforced concrete. For this purpose, three families of concrete were composed using strapping strap fibers, steel fibers, and polypropylene fibers, which were introduced into a concrete composition by volumetric substitution (0.4%, 0.8% and 1.2%) of aggregates. The fresh properties were evaluated through slump, density and air content tests. Hardened properties were investigated using the compressive and flexural strengths, pulse velocity, dynamic elastic modulus, and water absorption tests. The results obtained showed that strapping strap waste fibers significantly improve the mechanical properties of fiber-reinforced concrete and have a behavior similar to that of steel fibers. The optimum rates of strapping strap fibers were 0.4% and 1.2% for compressive and flexural strengths respectively. Compared to polypropylene fibers, the strapping strap fibers were found to be more efficient and led to a gradual increase in flexural strength with an increase in the strapping strap fibers. The results obtained also showed that the increase in strapping strap fiber content gradually increased the water absorption of fiber-reinforced concrete.</p> </abstract>ARTICLEtrue Behavior of Double-Layered Grids<abstract><title style='display:none'>Abstract</title> <p>This study presents a numerical approach to an analysis of the mechanical behavior of double-layered tensegrity grids. We present a comparative study on the behavior of tensegrity grids through geometric nonlinear analysis (GNA) and combined nonlinear analysis (CNLA) (geometric and material), considering the possible effect of evolution in the elasto-plastic domain of the cable elements. The effect of the relaxation of cable on the amplification of the displacement of these grids was taken into account. The updated Lagrangian formulation, which modifies the Newton-Raphson iterative scheme with incremental loading, was adopted. We have developed a numerical computational model specific to tensegrity structures that simulates the geometric and material nonlinear behavior. The reliability of the calculation tool developed has been validated. Additionally, the results of the application of the numerical model on a grid, which was generated based on demi-cuboctahedral tensegrity cells, are presented.</p> </abstract>ARTICLEtrue of Olive Stones with a View to Their use as Lightweight Aggregate in Construction Mortars<abstract><title style='display:none'>Abstract</title> <p>In countries that are big producers of olive oil such as Spain, Italy, or Greece, large amounts of olive husk remain as waste from processing olives and pose a serious environmental issue. One of the solutions could be to use this waste to partially replace sand in cement mortar to preserve the environment, decrease the consumption of cement, and improve economic benefits. This work presents our initial results which show the viability of using olive waste as an aggregate in cementitious mortars, indicating that the organic materials studied can be promising for this purpose.</p> </abstract>ARTICLEtrue Angle of the Shear Resistance of Danube Gravel Derived from the Dynamic Penetration Test<abstract> <title style='display:none'>Abstract</title> <p>The dynamic penetration test was used to investigate the angle of shear strength of Danube gravel. The correlations for its determination are available in the standards and literature. From the data set of the results, the characteristic value of the angles of shear strength was derived according to the recommended statistical procedure from the second generation of Eurocode 7. The characteristic values of the angle of shear strength were evaluated for well-graded gravels, poor-graded gravels, and gravels with fine-grained particles of the Danube. The correlations, which were based on field tests and considered the genesis of the soil, were compared with laboratory test results and a table of the values from the Slovak standard, which are used for purposes of comparison.</p> <p>In our research we compared the characteristic field values of the angle of shear strength obtained in the laboratory to observe the effect of their genesis on the appropriateness of the correlations used. We conclude with recommendations for the regional correlations and suggest values of the angle of shear strength for the classes of gravels tested.</p> </abstract>ARTICLEtrue of Cracks in Concrete with the Microbial-Induced Calcite Precipitation (MICP) Method<abstract> <title style='display:none'>Abstract</title> <p>In this study, the microbiologically-induced calcium carbonate precipitation (MICP) method was employed to examine its potential for repairing cracks in concrete. In addition, specific gravity and porosity values were measured to examine the effect of calcite formations on concrete surfaces and microstructures. Bacteria-supplemented concrete repaired cracks up to 0.4 mm wide by filling them with CaCO3. Furthermore, this study not only examined the healing of the width but also the length of cracks. However, as the width of the treated cracks decreased, their length increased. This indicated that the MICP treatment is more effective in a limited crack range. Specific gravity values increased, and porosity values decreased in concrete supplemented with calcifying bacteria. SEM analyses showed that calcite is a bacterial product that forms a very tight bond with a cement gel and that calcite fills visible cracks and voids and creates more of a void-free and undamaged concrete structure.</p> </abstract>ARTICLEtrue of Recovered Fibers on the Behavior of Concrete in Tension<abstract> <title style='display:none'>Abstract</title> <p>This study evaluates the performance of concrete under the effect of the addition of non-straight fibers recovered during the machining of steel parts and then studies the effect of the addition of corrugated fibers (chips) on their behavior in direct traction of the fiber concrete. In order to characterize the mechanical behavior and tearing of these fibers, three lengths of fibers were used (4 cm, 5 cm, and 6 cm); for each length we varied the percentage by volume (0.3%, 0.5%, 0.8%, 1%, and 1.2%). To make a comparative study, a second series of tests was carried out with control concrete (BT) without any fibers of the same composition. The results of the tests carried out indicate that the resistance and stiffness are significantly improved and that the fibers imparted significant ductility to the material compared to the control concrete. It was also observed that the percentage of fibers significantly influences the appearance of cracks. Moreover, with an increase in the percentage of fibers from 0.3% to 0.8%, the resistance increases, but beyond a content of 0.8%, the mechanical characteristics decrease.</p> </abstract>ARTICLEtrue Contribution to Study the Physico-Mechanical and Thermal Properties of Lightweight Cellular Concrete Prepared With Different Types of Sand and Waste Marble Powder<abstract> <title style='display:none'>Abstract</title> <p>Algeria is currently undergoing an evolution in civil engineering, which has resulted in a higher use of aggregates, especially sand. This study contributes to the development of locally produced materials. Its goal is to explore how the type of sand and waste marble powder (WMP), which can be used as a partial replacement of cement and aluminum powder (Al) with different percentages as an expansive agent, can affect physico-mechanical properties such as the bulk density and mechanical strength at 28 and 90 days, as well as the thermal conductivity of lightweight cellular concrete. Non-autoclaved cellular concretes (CC) were investigated based on three types of sand, i.e., sea sand (SS), river sand (RS), and waste marble sand (WMS); a hydraulic binder (a mix of cement and waste marble powder), and aluminum powder. The experimental results indicate that the nature and particle size distribution of the sand used had an impact on the properties of the CCs. Furthermore, it can be seen that the increased aluminum contents decrease the density, mechanical strength, and thermal characteristics of the CCs. Using 10-15% WMP as a cement substitute improves the mechanical strength, offers better thermal conductivity values, and contributes to sustainable development by developing a new class of environmentally friendly cellular concrete.</p> </abstract>ARTICLEtrue Use of Vertical Gardens as a Network of Urban Navigation Elements with a Positive Impact on Biodiversity and Microclimate in a Dense Urban Environment<abstract> <title style='display:none'>Abstract</title> <p>Horizontal green areas are becoming valuable, yet extruded spots, and their constant elimination at the expense of commercial and housing developments is disrupting green infrastructure. Interlocked existing urban structures seldom allow for the creation of parks and larger green open spaces, which could provide a habitat for a wide range of insects, birds, and other small animals. The lack of green spaces causes urban heat islands (UHI) over the cities. Vertical gardens are alternative solutions for urban areas, where it is not possible to increase biodiversity by creating new horizontal green areas. They effectively utilise surfaces that would otherwise be unused and transform them into effective green infrastructure elements.</p> <p>Using the example of the historical city district of Bratislava, i.e., Old Town (Staré Mesto) in Slovakia, we present an alternative approach for resolving the lack of green areas. A case study was conducted to create a map of all the potentially suitable areas for the construction of vertical gardens. We divided these spots into three groups, i.e., walls, columns, and free-standing structures and proposed construction methods for each type. Regarding the placement of potentially suitable areas along the roads connecting important transport hubs with the city centre, we created an original proposal for a district-wide network of vertical gardens as orientation elements for tourists and residents with significant aesthetic merit as well as ecological and hygienic values.</p> </abstract>ARTICLEtrue of the Indoor Climate in a Small, Newly-Built Auditorium<abstract> <title style='display:none'>Abstract</title> <p>The article focuses on an analysis of the indoor climate in a small, newly-built auditorium. Providing optimal indoor climate parameters in the interiors of a university is extremely important for students. Meeting these parameters is essential not only from a physiological point of view, but also to achieve desirable student performances. The parameters of CO2 concentration are also influenced by the air distribution system in a small auditorium. The correct positions of the supply and extract air is very important. The first experimental measurements of CO2 concentration were carried out in a small auditorium in an old building. The natural ventilation of the small auditorium was evaluated. The second experimental measurements of the CO2 concentration were made in a small auditorium in a newly-built building. The ventilation system and the modern air distribution system of the small, newly-built auditorium were evaluated based on the CO2 concentration and the PMV index. A Testo 480 was used for the measurements. The conclusion of this paper contains the recommendations for the design of a newly-built ventilation system in a small auditorium.</p> </abstract>ARTICLEtrue of an Embankment on Stone Column-Reinforced Soft Soil<abstract> <title style='display:none'>Abstract</title> <p>Reinforcing soft soils with good drainage and load-bearing material is a common practice in the construction of embankments. Stone columns are among the granular materials that accelerate consolidation settlements due to their high drainage capacities. This study aims to investigate the behavior of an embankment on stone column-reinforced soft soil. The embankment was analyzed using the Plaxis 2D Finite Element Method. The columns were converted into equivalent walls using the plane strain conversion method. This method was validated with field measurement results from previous studies and showed good agreement. According to the research findings, stone columns significantly reduced deformations and improved consolidation. For instance, the ultimate settlement was decreased from 54.3 mm to 33.1 mm for 10% and 20% area replacement ratios, respectively. As the safety analysis verified, basal geosynthetics contributed substantially to the embankment’s stability. Furthermore, the safety factor values increased for all stages of the construction, and the global safety factor increased at the end of the construction. Stone columns and basal geogrid-reinforced soft soil can reduce settlement and increase the stability of an embankment.</p> </abstract>ARTICLEtrue of a Conceptual Snow Sub-Model: Application in Meteorological Stations, Slovakia<abstract> <title style='display:none'>Abstract</title> <p>A semi-distributed rainfall-runoff Approximate Redistributive Balance (ARB) model is currently in development as a tool for the assessment and analysis of the water management balance at the level of micro-basins on the territory of Slovakia. For the winter season, it is necessary to supplement the model with a sub-model for calculating the snow water equivalent (SWE) with a comparatively low amount of the input data necessary. Since SWE models generally operate in a daily time step, a new sub-model was developed and tested in monthly and weekly time steps in 30 meteorological stations in the north of Slovakia. When compared in a weekly time step with the snow sub-model of the HBV rainfall-runoff model and when the impact of switching from a monthly to weekly time step on the quality of the runoff simulation was evaluated, the results showed that the snow sub-model does react to sudden snowmelt better when compared to the modified version of the HBV snow sub-model used. Using a weekly time step for the snow sub-model in a monthly ARB model runoff simulation showed an increase of accuracy (NSE change from 0.89 to 0.92) in one case, while maintaining the same level of accuracy in the second one.</p> </abstract>ARTICLEtrue of Embankment of an Ore Tailings Pond and an Analysis of its Stability<abstract> <title style='display:none'>Abstract</title> <p>The article presents a method for the intensification of a tailings pond. A tailings pond serves for the hydraulic storage of silt-sand waste arising during a flotation treatment and the processing of polymetallic ores. The intensification of the tailings pond consisted of raising its dam system to increase its accumulation space. The total proposed height of the tailings pond dam system after its elevation will be 60 m. The structural and shape arrangement of the dam in the dam system of the tailings pond was the result of a stability analysis of the state of the tailings pond before and after the dam system was raised. The article presents the results of experimental verifications of the geomaterial properties that form quasi-homogeneous units of the tailings pond (subsoil, dam system, and sediment) that serve as the inputs for stability analyses. New limiting and critical water levels are modelled based on the stability analysis for the intensified dam system of the tailings pond, taking into account the standard requirements for its overall stability.</p> </abstract>ARTICLEtrue of the Probability of Exceeding the Limiting Deformations of a Building Foundation<abstract> <title style='display:none'>Abstract</title> <p>The level of ground settlement under the effect of certain factors is one of the markers indicating the adequacy of adopted design solutions. By comprehending settlement values, it is possible to infer the degree of risk associated with a project and, if necessary, introduce changes to the design. The concept of reliability management here manifests itself in the timely adjustment of the decisions made, while it is necessary to use the procedure of the quantitative assessment of the probability of the occurrence of a particular limit state. A qualitative assessment indicates only the limits of an area, which approximately characterizes the effects of changes in the geotechnical situation. In this article, a method for determining the probability of exceeding the limit deformation of a building-base massif using the Monte Carlo statistical method is developed, and an algorithm and computer program implementing the proposed calculation method are created.</p> </abstract>ARTICLEtrue and Modification of Chip-Cement Wooden Composites Based on Recycled Plastics<abstract> <title style='display:none'>Abstract</title> <p>The production of plastics and the associated increasing amount of plastic waste is currently a serious environmental problem that has a negative impact on the environment. It is necessary to develop new methods of recycling and also solutions for the further use of already recycled plastics. Thus far, a lot of research has been devoted to this issue, which focuses on the effective recycling and reuse of recycled plastic in the construction sector. One of the possibilities is the application of a filler substitute in concrete, which is an economically and ecologically advantageous solution that ensures optimal thermal insulation and acoustic properties. The aim of this study was to analyze the potential replacement of conventional aggregates in lightweight concrete, with a filler made of recycled plastic with a lower bulk density. In the research, wood chips were used in combination with recycled waste fillers including polystyrene (SE), polyethene (SP), and polyurethane foam (SU) in ratios of 1:3, 1:1, and 3:1 as an alternative to conventional filler. Concrete composites from these materials were prepared and characterized by their bulk density, thermal conductivity and compressive strength parameters.</p> </abstract>ARTICLEtrue of the Constructive Nonlinearity of Ribbed Reinforced Concrete Slabs of Self-Stressed Covering Panels<abstract> <title style='display:none'>Abstract</title> <p>Precast reinforced concrete constructions meet the requirements of industrialization, high manufacturability, and cost-effectiveness at a reasonably high level. The ribs in constructions perform load-bearing functions, and the slab part performs enclosing functions. Often before the installation of such structures at a construction site, they are mounted from assembly elements. The overall dimensions of the elements are limited by transportation requirements. During such an aggregated mounting, the assembly units work according to a calculation scheme that differs from an operational scheme. The structural nonlinearity of ribbed reinforced concrete slabs during transportation, mounting, and installation, and the operation of a combined spatial covering panel were investigated in this paper. The effects were identified, and a rational design of nodes connecting the individual prefabricated units into a spatial structure was developed. With the help of these nodes, it is possible to create unloading support moments, which will reduce the internal forces in the design cross-sections. The effects of changes in the width of the reinforced concrete slab shelves on the internal forces of the load-bearing ribs of a wall and a roof panel were investigated.</p> </abstract>ARTICLEtrue Study on Concrete by Adding Polyester Fibres<abstract> <title style='display:none'>Abstract</title> <p>There are increased innovations in the field of concrete because there are endless opportunities for innovative materials, techniques, applications, and design. Today’s construction industry is looking for cost-effective materials to improve the strength of concrete structures. As a result, an attempt has been made in the current research to investigate the impact of adding polyester fibres (Recron 3s) to concrete. Fibres improve concrete's tensile and flexural strength, fatigue properties, durability, shrinkage properties, impact and erosion resistance, and serviceability. Polyester fibres (Recron 3s) are micro fibres; they contribute to enhancing the resistance of concrete to shrinkage and cracking and also help to improve mechanical properties such as the flexural / split tensile and transverse strength of concrete along with improvements in abrasion and impact strength. An experimental study was done using a M30 mix design. Polyester fibres (Recron 3s) were used in the concrete with varying dosage rates of 0.50 kgs / cu.m – 2.00 kgs / cu.m. This study describes the enhancement in the strength of the M30 grade mix concrete by the addition of polyester fibres (Recron 3s) in the proportions of 0.5, 1, 1.5, 2.0kg/cu.m, and M30 concrete with varying dosages of the polyester fibres (Recron 3s) were mixed and cast.</p> </abstract>ARTICLEtrue