rss_2.0Slovak Journal of Civil Engineering FeedSciendo RSS Feed for Slovak Journal of Civil Engineering Journal of Civil Engineering 's Cover Run-Ups and Overtopping Affected by Oblique Wave Approaches and Currents<abstract> <title style='display:none'>Abstract</title> <p>To quantify the effect of a current on the height of a wave’s run-up and overtopping combined with an oblique wave approach, the “FlowDike” hydraulic research project was carried out. Tests were performed on two dike slopes of 1:3 and 1:6. Waves were generated across (perpendicular to) the physical model and also inclined in-plane to the stream axis. Oblique waves were generated both towards and along the flow’s direction. The effect of the current and of the wave direction on the height of the wave run-up and amount of the wave overtopping was expressed by means of a combined correction factor for the wave’s inclination and flow velocity. The results of the research confirmed that the flow velocity had only a small effect.</p> </abstract>ARTICLE2022-07-12T00:00:00.000+00:00Lidar-Based Mobile Mapping System for an Indoor Environment<abstract> <title style='display:none'>Abstract</title> <p>The article deals with developing and testing a low-cost measuring system for simultaneous localisation and mapping (SLAM) in an indoor environment. The measuring system consists of three orthogonally-placed 2D lidars, a robotic platform with two wheel speed sensors, and an inertial measuring unit (IMU). The paper describes the data processing model used for both the estimation of the trajectory of SLAM and the creation of a 3D model of the environment based on the estimated trajectory of the SLAM. The main problem of SLAM usage is the accumulation of errors caused by the imperfect transformation of two scans into each other. The data processing developed includes an automatic evaluation and correction of the slope of the lidar. Furthermore, during the calculation of the trajectory, a repeatedly traversed area is identified (loop closure), which enables the optimisation of the trajectory determined. The system was tested in the indoor environment of the Faculty of Civil Engineering of the Slovak University of Technology in Bratislava.</p> </abstract>ARTICLE2022-07-12T00:00:00.000+00:00Investigation of the Liquefaction Potential of Coal Ash Due to Seismic Loading<abstract> <title style='display:none'>Abstract</title> <p>Coal ash is a geomaterial with a metastable structure. This type of geomaterial is significantly susceptible to liquefaction as a result of seismic loads. An investigation of ash that is susceptible to liquefaction due to a seismic load can use the CPT penetration test. This method of investigating liquefaction was developed based on numerous penetration tests of sandy or silty–sandy soils and was developed at the Workshop on the Evaluation of Soil Liquefaction Resistance, NCEER, Salk Lake City, Utah, USA, 1996. In the present article, the results of the CPT penetration test conducted at the Rosina ash tailings pond in Žilina in Slovakia, are analyzed using the NCEER methodology. The safety factor for ash liquefaction was expressed based on the penetration resistance values measured in the CPT tests using the ‘LiquefyPro’ software. The safety factor in the liquefaction of the ash sediment was expressed by changing the level of seeping water in the body of the tailings pond, the unit weight of coal ash, and the seismic acceleration.</p> </abstract>ARTICLE2022-07-12T00:00:00.000+00:00Smart-Readiness Assessment of a Complex Residential Building in Ukraine<abstract> <title style='display:none'>Abstract</title> <p>Smart building concepts are a relevant topic for the Ukrainian building sector. Although the current policy is mostly dedicated to the improvement of the current energy-saving situation in the building stock, the concept discussed could provide valuable inputs in the realization of the existing strategy. For an assessment of the expected positive impact of the implementation of smart indicators on building operation and renovation processes, as well as the predictions of scenarios of the range of the application of smart instruments, the research presented proposes a thorough analysis of the building stock in Ukraine and, in a real pilot case, the assessment of smart-readiness indicators (SRI) for a complex multi-family building. The case scenarios used, which are derived on the basis of SRI and a processed questionnaire among the habitants, are considered as the reference foundation for a practical application and disseminating the concept for similar cases.</p> </abstract>ARTICLE2022-07-12T00:00:00.000+00:00A Comparison of Variational Projection and Cartographic Projection by Ritz’s Method<abstract> <title style='display:none'>Abstract</title> <p>The application of alternative mathematical methods in creating cartographic projections is an interesting factor, which affects the optimization of distortions and their distribution in the projected territory. This article presents the methodology for the creation and comparison of conformal cartographic projections formed by alternative mathematical methods of minimizing the integral criterion for scale distortion in Slovakia. The creation of the variational projection is based on the Airy-Kavraiskii criterion of evaluating the projection on the displayed area by solving Laplace's equation. The second projection is created by solving Poisson's equation using Ritz's method. Our analysis showed that the variational projection of Slovakia achieves more satisfactory distortion values than the cartographic projection created using Ritz's method. The advantage of Ritz's method is that it is possible to choose a boundary condition for a predefined undistorted convex closed curve. In this paper, we have also derived specific members of the map equations for cartographic projection based on solving Poisson's equation by Ritz's method.</p> </abstract>ARTICLE2022-07-12T00:00:00.000+00:00Possibilities of Applying Multivariable Regression in Groundwater Data Series along a Riverbank Area<abstract> <title style='display:none'>Abstract</title> <p>Groundwater modelling needs a large number of piezometer well data, which is unfortunately not always available as earlier registered data series are not always continuous. The reconstruction of data series with gaps was previously examined on a small riverside pilot area with the help of multiple regression, this method has now been tested at a 50-times larger environment. The results show that the reconstruction of the data series with this method works with average monthly groundwater levels and that applying multiple regression with the independent variables being one of the wells and the river optimizes the accuracy of the calculated data series, even if the relationships between the river and the wells are weak. The effect of the multiple regression on the accuracy is greater if the data series is sparser.</p> </abstract>ARTICLE2022-07-12T00:00:00.000+00:00Impact of Changes in Short-Term Rainfall on Design Floods: Case Study of the Hnilec River Basin, Slovakia<abstract> <title style='display:none'>Abstract</title> <p>The research aims to analyze changes in the predicted short-term rainfall intensities at the Telgárt climatological station and the subsequent use of these predicted rainfall intensities for estimating design floods. The area of interest selected is the upper Hnilec River basin in Slovakia. The research is divided into two parts: In the first part, the authors have focused on analyzing future seasonal changes and the trend of shortterm rainfall intensities and estimating the scaling exponents of short-term rainfall. In the second part, the observed and predicted short-term rainfall intensities have been applied to estimate the design floods in the study area, using the Soil Conservation Service – Curve Number method (SCS CN). The results indicate that for the future periods, there will be a shift in the rainfall maxima of about one week to an earlier period in July compared to the historical period. The changes in the short-term rainfall trends were detected in the 60-, 120- and 180-minute rainfall durations at the 90% significance level. The results of the design discharges predict higher values in the near future in the case of the 10- and 20-year return periods and higher values in the 50- and 100-year return periods for the remote future.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Specific Design Features of Prefabricated Fire-Resistant Floor Slabs Made from Lightweight Concrete<abstract> <title style='display:none'>Abstract</title> <p>Reinforced concrete roof and floor structures have the highest heating temperatures and are exposed to the most difficult conditions during fires that occur in buildings and structures. The standardized fire resistance of hollow-core slabs made of heavy concrete from Portland cement is regulated as REI 45 or REI 60. The aim of the work is to develop a composition of lightweight fire-resistant concrete and architectural engineering for floor slab devices. The composition of lightweight fire-resistant concrete made from expanded clay aggregates and alumina cement was developed as a result of the work. The degree of fire resistance of the lightweight concrete composition with a bulk density of 1475 kg/m<sup>3</sup> has been practically determined; i.e., REI 90. The structural solution of the floor slab has been improved; at the same time, we propose to develop a slab with a flat section made of lightweight fire-resistant concrete. Such floor slabs, along with an increase in the fire resistance limit, improve the heat-insulating ability of a floor due to a significant reduction in the coefficient of the thermal conductivity of lightweight concrete.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00The Impact of Climate Change on Stochastic Variations of the Hydrology of the Flow of the Indus River<abstract> <title style='display:none'>Abstract</title> <p>Pakistan’s agricultural economy is reliant on the Indus River’s irrigation system, which is fed by the water coming from the great Himalayas-Karakoram Glacier Mountains. Because of hilly terrain areas, the climatic variations have an intense effect on the river flow, especially during the winter and monsoon months. Consequently, significant variations, which are observed annually, result in flooding situations in the monsoon months and reduced flows in the winter season. Thousands of people have lost their lives and massive property destruction has taken place due to disastrous floods that occurred during 2010 and 2016. Past studies have focused on proper water resources and the management of extreme events such as floods and droughts; however, modelling and forecasting based on the various climatic factors and stochastic variations are rare. This paper attempts to forecast Indus River flows using multiple linear regression (MLR), the stochastic time series, the seasonal autoregressive integrated moving average (SARIMA), and its reduced heteroscedasticity model, i.e., SARIMA-GARCH (generalized autoregressive conditional heteroscedasticity) methods at the Kalabagh station. The results show that MLR is best over the short-term; SARIMA is better over the long-term, and SARIMA-GARCH may be superior for a very long-term forecast.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Theoretical Correlations Between the Cumulative Absolute Velocity and Performance Point for a Seismic Analysis of Framed Structures<abstract> <title style='display:none'>Abstract</title> <p>The present paper investigates the effect of the harmfulness of a potential earthquake on structural and seismic risks. It takes into account the magnitude, epicentral distance, and pseudo depth at the hypocenter as well as the soil classification in order to generate synthetic seismic motions to be considered as signal inputs for a structural seismic analysis. The most typical typology of dwellings and buildings that are widely existing in Algeria, i.e., a reinforced concrete frame structure, is considered for the case study. The results show that the theoretical models developed in this study are able to predict the performance point (spectral displacement) according to the cumulative absolute velocity. They also show that(CAV-S<sub>d</sub>) (S<sub>d</sub> being the spectral displacement of the performance point defined by a pushover analysis) is slightly influenced by the value of the ultimate displacements of the structures and the soil parameters (shear velocity Vs).</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00A Study on the Applicability of a Swat Model in Predicting the Water Yield and Water Balance of the Upper Ouémé Catchment in the Republic of Benin<abstract> <title style='display:none'>Abstract</title> <p>This study investigates the applicability of a Soil and Water Assessment Tool (SWAT) model in predictions of the water yields and water balance of the Upper Oueme catchment in the northern part of the Republic of Benin. Meteorological and hydrological data for a period of 20 years were collected from the Meteorological Agency of Benin and the National Directorate of Water respectively. Spatial data such as a Digital Elevation Model and land use and soil maps were also extracted from suitable databases. Geographic information system (GIS) software was applied in combination with SWAT to process the spatial data and simulate the streamflow record. A good correlation between the simulated and observed data during the calibration and validation was found, using statistical measures such as the Nash-Sutcliffe Efficiency (NSE&gt;0.65%), the standard deviation ratio (RSR&lt;0.6), percent bias (±10%≤PBIAS&lt;±15%), and the coefficient of determination (R<sup>2</sup>=0.78). An estimated potential water yield of 18,671.61mm in the catchment over the period of the simulation suggests that subsistence agriculture is sustainable in the area. The model is suitable for estimating the water yield and water balance in the catchment.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Numerical Study on the Effect of Water Waves and Depths on Inclined Braces with Respect to the Stability of VLFS Platforms in the Caspian Sea<abstract> <title style='display:none'>Abstract</title> <p>Very large floating structures (VLFSs) have various applications, such as recreational applications, port facilities, etc. A surge in the population, the advantages of building floating structures compared to traditional methods of land extraction from the sea, and the development of construction technologies, have led to engineers paying attention to very large floating structures. Bracing systems are capable of controlling and reducing the horizontal responses of a floating platform, but they have no major impact on its vertical responses. In the present study, the semi-floating platform was numerically designed to be least affected by the three factors of wave force, horizontal torsion, and horizontal displacement. In order to optimize the design, the semi-floating platform was simulated and subjected to the three wave directions with collision angles of 40, 45 and 55 degrees in the environmental conditions of the Caspian Sea and by exerting the wave effect in a Flow-3D model. Examination of the platform’s movements has demonstrated that the arrangement of an eight-way restraint system with a 40-degree restraint angle responds better to the impact of waves and is more economical compared to other designs.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Effecting the Rheological Properties of Composites for 3D Printing Technology in Construction<abstract> <title style='display:none'>Abstract</title> <p>The article deals with the factors that lead to the beginnings of the solidification and hardening of materials used in 3D home printing technology in construction. At the beginning, the composition of the materials as well as their essential fresh and hardened properties and the performance assumptions of such a mixture are described. Subsequently, the article discusses the main aspects of the rheology and hydration of cement composites and the use of additives such as superplasticizers, viscosity modifiers, and acceleration and retardation additives, which directly affect the onset of the setting of such materials and the strength of the resulting mixtures. Finally, we describe the printing and curing process of the extruded material, which is divided into 4 main phases from the pumping and extrusion of the material through the initial deposition of layers to a sufficient increase in strength in the required time.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00A New Approach for Determining the Curvature Ductility of Reinforced Concrete Beams<abstract> <title style='display:none'>Abstract</title> <p>This paper presents a numerical parametric study of the moment-curvature and curvature ductility of doubly-reinforced beams with different parameters. The effects of the strength of the concrete and the amount of the reinforcement, including the tensile and compression reinforcement on the complete moment-curvature behavior and the curvature ductility factor of the beam sections, have been studied. A new predictive formula for the ductility factor of beam sections that considers the different parameters has been developed. In a continuation of the study, the flexural ductility of beams designed with different parameters according to the ductility factor proposed by different researchers was investigated. Based on the results of the numerical analysis, the proposed predictions for the curvature ductility factor were verified by comparisons with other predictive formulas. The proposed formula offers fairly accurate and consistent predictions for the curvature ductility factor of beam sections. It is shown that the concrete’s compression strength and the amount of reinforcing steel, including the compression reinforcement ratios, have an effect on the curvature ductility factor of beam sections.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Research on a Trackside Concrete Reinforcement Scheme of a Small Radius Curve at a Junction Section of a Modern Tram<abstract> <title style='display:none'>Abstract</title> <p>In order to ensure the normal use of a junction section of a modern tram, this paper mainly studied a trackside concrete reinforcement scheme. Firstly, the entire non-reinforcement system model with a small radius curve composed of rail, fastener, fastener cover, flexible material, asphalt layer and track slab was established using the ABAQUS finite element software, and the stress distribution and deformation state of the asphalt layers of the non-reinforcement system model under the social vehicle load were analyzed. Then, the whole system model of the concrete reinforcement scheme was founded, and the stress and deformation of the asphalt layers under the same load were investigated. Finally, the calculation results of the concrete reinforcement model were com-pared with those of the non-reinforcement model, and the reinforcement effect was studied. The results show that the concrete reinforcement scheme significantly reduces the stress and deformation of the asphalt layers and improves the stress distribution and deformation state of the asphalt layers.</p> </abstract>ARTICLE2021-12-30T00:00:00.000+00:00Analysis of the Effect of the Speed Factor on Highway Safety Using the Machine Learning Method<abstract> <title style='display:none'>Abstract</title> <p>Speed is one of the most important factors that can significantly change the severity of accidents. Providing a model with predictive factors leads to designing traffic plans to promote safety. This study aims to create statistical models for accidents occurred on Firuzkuh highway, Iran. Moreover, the probability of each type of accident was determined using the logit model. Various modeling methods, such as backward, forward, and entering methods, were evaluated to find the best method. Finally, since the backward method had the best performance in terms of R2 and goodness of fit, the logit model of accidents was created. According to the model, the independent variables of the 12-24 hours, rainy weather, a speed of 81-95 and 96-110 km/h, the lack of attention ahead and the Pride brand of vehicle increased the severity of accidents, while the variables with negative coefficients of Tuesdays, the summer and spring seasons, sunny weather, a male driver, and daylight, reduced the severity of accidents.</p> </abstract>ARTICLE2021-12-30T00:00:00.000+00:00Assessment of the Energy Demands for Heating in an Historic Building. Case Study: Renewal of a Functionalist Building of the Infectious Diseases Pavilion in Topoľčany, Slovakia<abstract> <title style='display:none'>Abstract</title> <p>The case study seeks an optimal solution for preserving the cultural values of a functionalist building so that it fulfils the legislative essence of the protection of a historic building and, at the same time, contributes to the improvement of its thermophysical properties. The paper focuses on the degree of the application of energy performance requirements for the adaptive reuse of a historic building. The efforts to preserve cultural values (architectural, aesthetic, the value of the authenticity of an area and its building constructions, etc.) in legally protected buildings often do not permit the application of building construction processes such as those used in ordinary older buildings. The research responds to a situation where a building with historic values, built in a functionalist style (the 1940s), permits variants of the surface treatment of the facade so as to not disturb the essential stylistic values of that facade and, at the same time, reduce its energy demands to the required value.</p> <p>Heat demands for heating have a significant effect on the energy needs for heating and thus on the overall energy need of a building. The heat demands depend on the efficiency and quality of the thermal protection in buildings. In the case of cultural monuments, the calculation of the thermophysical properties of building structures forms the basis for determining the heating and cooling demands. Building structures and their elements that form the building envelope must meet current and demanding thermophysical requirements in accordance with the applicable standards, if technically and economically feasible. When restoring cultural monuments in the Slovak Republic, it is not required to meet requirements for energy efficiency. On the other hand, it is necessary to verify the thermophysical requirements in accordance with the applicable standards in each specific case.</p> <p>The paper responds to a continuing interdisciplinary discussion on this topic. The analysis is conducted within the scope of the KEGA 016STU-4/2017 project.</p> </abstract>ARTICLE2021-12-30T00:00:00.000+00:00Causes of Failures in Circular Concrete Silo Walls, Particularly Under Environmental Influences<abstract> <title style='display:none'>Abstract</title> <p>The paper reports the results of a case study for achieving longer service life and increasing the environmental sustainability of concrete silos. Damage mechanisms in concrete silo walls, and respectively in cylindrical structures (e.g., chimneys, cooling towers, and tanks), are widely diverse. The common causes of failures include those due to poor design considerations, construction deficiencies, non-compliance with operational rules and regulations, lack of maintenance, and insufficient and/or corroded reinforcements, together with the environmental conditions affecting the walls. In addition to the ultimate limit state design, temperature-induced cracking may often be underestimated in the design of reinforced concrete silos, leading to premature deterioration and losses in serviceability. Cracks from environmental or service conditions facilitate the ingress of moisture and corrosive agents. Therefore, there is an increased interest in reducing the appearance of cracks and limiting their width. The aim of this paper is to highlight the synergistic effects in the design, construction, and operation of silo walls, particularly under varying environmental influences. The research undertaken indicates that systematic errors can be identified and corrected.</p> </abstract>ARTICLE2021-12-30T00:00:00.000+00:00Extensive Roof Greenery as a Response to Heat Islands: Some Problems<abstract> <title style='display:none'>Abstract</title> <p>Extensive roof greenery is one of the ways to reduce the extent and impact of urban heat islands. A prerequisite is the correct design and operation of both the structural and vegetation part of a roof. If adequate maintenance, especially irrigation of the greenery, cannot be ensured, the use of extensive roof greenery can also be counterproductive. The case study to be presented deals with problems of a flat roof with extensive greenery above an underground garage under Central European climate conditions. Infrequent irrigation leads to extremely high temperatures of the substrate in the summer and makes the purpose of this roof pointless. The contribution analyzes the reason for the failure of the vegetation part of the roof, which was claimed to be maintenance-free, points out fire safety issues, and suggests improvements that might be considered in similar cases. At the present time, which is marked by the climate change crisis, there is great societal pressure to build green roofs. However, if it is not possible to ensure their perfect functionality, it is perhaps better to use classically proven types of roofs, but with greater reflectivity of the top layer surface.</p> </abstract>ARTICLE2021-12-30T00:00:00.000+00:00Detection of Changes in the Hydrological Balance in Seven River Basins Along the Western Carpathians in Slovakia<abstract> <title style='display:none'>Abstract</title> <p>Due to a changing climate, likely changes to a hydrological regime are one of the primary sources of uncertainty to consider in managing water resources. In Slovakia, a decline in the country’s water resources, combined with a change in the seasonality of runoff and an increase in the extremeness of floods and droughts, represents a potential threat. The objective of the paper was to explore trends in the components of the long-term hydrological balance of various river basins to detect the impacts of changing climate conditions along the Western Carpathians. The proposed method is a comparative exploratory analysis of the hydrological balance of the selected river basins. Temporal changes in the catchments’ average air temperatures, precipitation, runoff, and their differences (considered as an index of the actual evapotranspiration), were estimated for 49 years of data; two non-overlapping sub-periods (25 and 24 years) in the seven river basins were also compared. This work also aims at evaluating the applicability of gridded inputs from the CarpatClim database for modelling the hydrological balance over an extended period. The results document the impact of the rising air temperature and, in part, local physiographic factors on the changes in runoff and actual catchment evapotranspiration.</p> </abstract>ARTICLE2021-12-30T00:00:00.000+00:00en-us-1