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Détails du magazine
Format
Magazine
eISSN
1338-3973
Première publication
23 May 2011
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 29 (2021): Edition 4 (December 2021)

Détails du magazine
Format
Magazine
eISSN
1338-3973
Première publication
23 May 2011
Période de publication
4 fois par an
Langues
Anglais

Chercher

7 Articles
access type Accès libre

Causes of Failures in Circular Concrete Silo Walls, Particularly Under Environmental Influences

Publié en ligne: 30 Dec 2021
Pages: 1 - 8

Résumé

Abstract

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.

Key words

  • Failure analysis
  • Thermal stress
  • Corrosion
  • Cracks
  • Spalling
access type Accès libre

Extensive Roof Greenery as a Response to Heat Islands: Some Problems

Publié en ligne: 30 Dec 2021
Pages: 9 - 12

Résumé

Abstract

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.

Key words

  • Extensive greenery
  • Urban heat island
  • Flat roofs
  • Reflection
  • Absorption
access type Accès libre

Research on a Trackside Concrete Reinforcement Scheme of a Small Radius Curve at a Junction Section of a Modern Tram

Publié en ligne: 30 Dec 2021
Pages: 13 - 18

Résumé

Abstract

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.

Key words

  • Modern tram
  • Junction section
  • Small radius curve
  • Whole system model
  • Concrete reinforcement
access type Accès libre

Analysis of the Effect of the Speed Factor on Highway Safety Using the Machine Learning Method

Publié en ligne: 30 Dec 2021
Pages: 19 - 28

Résumé

Abstract

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.

Key words

  • Safety
  • Accident
  • Speed
  • Highway
  • Logit model
access type Accès libre

Assessment 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

Publié en ligne: 30 Dec 2021
Pages: 29 - 36

Résumé

Abstract

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.

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.

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.

Key words

  • Interdisciplinarity
  • Adaptation of historic building
  • Building energy assessment
  • Hygienic criterion
  • Indoor environmental quality
access type Accès libre

Risk Assessment Model Based on Fuzzy Logic for Residential Buildings

Publié en ligne: 30 Dec 2021
Pages: 37 - 48

Résumé

Abstract

Risk is involved in every construction project. Residential building construction projects comprise a variety of risks and are more likely to be affected due to their difficulty and many operations and threats. The study aims to identify the various risk elements and their effect on construction projects of residential buildings using a fuzzy approach with the help of MATLAB software. This study includes 60 risk factors recognised through an expert opinion and literature review. These factors are categorised into 7 major groups, i.e., construction, project manager, architect/consultant, contractor, owner, resources, and external environment-specific risk factors. A questionnaire was prepared and sent using emails based on the identified risk factors to be filled out by construction industry professionals in India and by conducting in-person interviews. Based on the risk severities obtained from the fuzzy model, the top 10 risk factors have been considered. As a result, for identified top severe risk factors, a significant risk response strategy was implemented.

Key words

  • Risk assessment
  • Construction industry
  • Fuzzy set theory
  • Fuzzy logic
access type Accès libre

Detection of Changes in the Hydrological Balance in Seven River Basins Along the Western Carpathians in Slovakia

Publié en ligne: 30 Dec 2021
Pages: 49 - 60

Résumé

Abstract

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.

Key words

  • Hydrological balance
  • Climate change
  • Evapotranspiration, Budyko-Tomlain
  • Detection of changes
  • Trend analysis
  • Western Carpathians
7 Articles
access type Accès libre

Causes of Failures in Circular Concrete Silo Walls, Particularly Under Environmental Influences

Publié en ligne: 30 Dec 2021
Pages: 1 - 8

Résumé

Abstract

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.

Key words

  • Failure analysis
  • Thermal stress
  • Corrosion
  • Cracks
  • Spalling
access type Accès libre

Extensive Roof Greenery as a Response to Heat Islands: Some Problems

Publié en ligne: 30 Dec 2021
Pages: 9 - 12

Résumé

Abstract

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.

Key words

  • Extensive greenery
  • Urban heat island
  • Flat roofs
  • Reflection
  • Absorption
access type Accès libre

Research on a Trackside Concrete Reinforcement Scheme of a Small Radius Curve at a Junction Section of a Modern Tram

Publié en ligne: 30 Dec 2021
Pages: 13 - 18

Résumé

Abstract

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.

Key words

  • Modern tram
  • Junction section
  • Small radius curve
  • Whole system model
  • Concrete reinforcement
access type Accès libre

Analysis of the Effect of the Speed Factor on Highway Safety Using the Machine Learning Method

Publié en ligne: 30 Dec 2021
Pages: 19 - 28

Résumé

Abstract

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.

Key words

  • Safety
  • Accident
  • Speed
  • Highway
  • Logit model
access type Accès libre

Assessment 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

Publié en ligne: 30 Dec 2021
Pages: 29 - 36

Résumé

Abstract

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.

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.

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.

Key words

  • Interdisciplinarity
  • Adaptation of historic building
  • Building energy assessment
  • Hygienic criterion
  • Indoor environmental quality
access type Accès libre

Risk Assessment Model Based on Fuzzy Logic for Residential Buildings

Publié en ligne: 30 Dec 2021
Pages: 37 - 48

Résumé

Abstract

Risk is involved in every construction project. Residential building construction projects comprise a variety of risks and are more likely to be affected due to their difficulty and many operations and threats. The study aims to identify the various risk elements and their effect on construction projects of residential buildings using a fuzzy approach with the help of MATLAB software. This study includes 60 risk factors recognised through an expert opinion and literature review. These factors are categorised into 7 major groups, i.e., construction, project manager, architect/consultant, contractor, owner, resources, and external environment-specific risk factors. A questionnaire was prepared and sent using emails based on the identified risk factors to be filled out by construction industry professionals in India and by conducting in-person interviews. Based on the risk severities obtained from the fuzzy model, the top 10 risk factors have been considered. As a result, for identified top severe risk factors, a significant risk response strategy was implemented.

Key words

  • Risk assessment
  • Construction industry
  • Fuzzy set theory
  • Fuzzy logic
access type Accès libre

Detection of Changes in the Hydrological Balance in Seven River Basins Along the Western Carpathians in Slovakia

Publié en ligne: 30 Dec 2021
Pages: 49 - 60

Résumé

Abstract

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.

Key words

  • Hydrological balance
  • Climate change
  • Evapotranspiration, Budyko-Tomlain
  • Detection of changes
  • Trend analysis
  • Western Carpathians

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