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Détails du magazine
Format
Magazine
eISSN
1338-3973
ISSN
1210-3896
Première publication
23 May 2011
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 27 (2019): Edition 1 (March 2019)

Détails du magazine
Format
Magazine
eISSN
1338-3973
ISSN
1210-3896
Première publication
23 May 2011
Période de publication
4 fois par an
Langues
Anglais

Chercher

8 Articles
Accès libre

Load – Displacement Behaviour of a Pile on a Sloping Ground for Various L/D Ratios

Publié en ligne: 06 Apr 2019
Pages: 1 - 6

Résumé

Abstract

An experimental study was carried out to understand the behaviour of a laterally loaded single pile on a slope with different length/diameter (L/D) ratios driven into cohesionless soil for a relative density of 70%. Static loading was applied in both forward and reverse directions for slopes of 1V:1.5H, 1V:2H, and 1V:2.5H for a constant L/D ratio representing flexible pile behaviour. It was observed that the load ratio (load on a sandy slope to the horizontal ground) decreased with an increase in the slope’s angle. The post-static behaviour of the pile under the same conditions was also studied to evaluate the elastic displacement, which increased with an increase in the slope’s angle. Due to the constant passive resistance under the reverse loading, the lateral load on the slope’s crest was almost equal to the horizontal ground’s condition. The effect of the L/D ratio was studied by varying the length and diameter and by maintaining the other parameter as a constant. The lateral load of a pile increased with an increase in its length and diameter.

Mots clés

  • Laterally loaded single pile
  • cohesionless soil
  • active slope
  • length to diameter ratio
  • stiffness factor
Accès libre

ADCP Discharge Measurements on the River Danube: Post-Processing and Correction of Data

Publié en ligne: 06 Apr 2019
Pages: 7 - 13

Résumé

Abstract

Accurate measurements and analyses of river discharges are one of the key tasks of hydrology. Nowadays, the traditional methods of discharge measurements are being supplemented or even replaced by novel approaches that utilize state-of-the-art technologies. One approach, which has recently become very popular in the hydrological practice both in Slovakia and abroad, is a method utilizing the Doppler effect of sound waves. In this study, a dataset of 185 discharge measurements on the River Danube was created using a RiverRay portable Acoustic Doppler Current Profiler (ADCP). All the measurements were taken on the River Danube at four different cross-sections in Slovakia. The measurements were processed using the manufacturer’s WinRiver II software and further adjusted in Agila, which is a specialised third-party post-processing software aimed at correcting measurement errors from ADCP discharge measurements. Currently, some but not all countries lying in the Danube basin have included Agila post-processing in their methodologies. This causes problems and disputes between national water authorities when exchanging information about discharge measurements in the border regions. In order to respond to this problem, the main objective of this study was to compare the results of both original and corrected discharges, which were measured under a number of different circumstances, and to propose recommendations about the suitability of using Agila post-processing for discharge measurements of the River Danube.

Mots clés

  • Discharge measurements
  • River Danube
  • ADCP
  • Agila software
  • Data post-processing
  • Doppler effect
Accès libre

Coupling Tank Model and Lars-Weather Generator in Assessments of the Impacts of Climate Change on Water Resources

Publié en ligne: 06 Apr 2019
Pages: 14 - 24

Résumé

Abstract

With the aim of assessing the impact of climate change on surface water resources, a conceptual rainfall-runoff model (the tank model) was coupled with LARS-WG as a weather generator model. The downscaled daily rainfall, temperature, and evaporation from LARS-WG under various IPCC climate change scenarios were used to simulate the runoff through the calibrated Tank model. A catchment (4648 ha) located in the southern basin of the Caspian Sea was chosen for this research study. The results showed that this model has a reasonable predictive capability in simulating minimum and maximum temperatures at a level of 99%, rainfall at a level of 93%, and radiation at a level of 97% under various scenarios in agreement with the observed data. Moreover, the results of the rainfall-runoff model indicated an increase in the flow rate of about 108% under the A1B scenario, 101% under the A2 scenario, and 93% under the B1 scenario over the 30-year time period of the discharge prediction.

Mots clés

  • Climate change
  • Impact
  • Downscaling
  • Rainfall-Runoff model
  • LARS-WG
  • Tank model
Accès libre

Characterization of Bitumen Binders on the Basis of Their Thermo-Viscous Properties

Publié en ligne: 06 Apr 2019
Pages: 25 - 31

Résumé

Abstract

Bitumen is one of the basic building materials that is mainly used in road construction. Nowadays, we can observe increased requirements for the quality of bituminous binders, which are due to increased traffic loads, changing climate conditions, and decreasing crude oil stocks. Besides “traditional” (empirical) tests (softening point, penetration), new types of tests have been developed that can better describe the quality and behavior of bitumen binders. Their composition can also be a significant part of the properties themselves. Therefore, the elemental and group composition of bitumen must also be observed. The use of the viscosity temperature susceptibility (VTS) test appears to be well suited to evaluate the properties of bitumen binders. The VTS parameter is directly dependent on the viscosity of bitumen, but it is necessary to say that VTS can be significantly affected by the composition of the bitumen. The paper is focused on determining the dependencies between the VTS and the bitumen’s composition, respectively, to find out how the composition influences the VTS.

Mots clés

  • Viscosity temperature susceptibility
  • Bitumen
  • Bitumen composition
  • Empirical tests
Accès libre

The Binder Index – A Parameter That Influences the Strength of Geopolymer Concrete

Publié en ligne: 06 Apr 2019
Pages: 32 - 38

Résumé

Abstract

Geopolymer concrete (GPC) is an environmentally friendly material in the sense that it uses industrial by-products such as ground granulated blast furnace slag (GGBS) and fly ash (FA), which are activated by an alkaline solution. This paper presents an experimental investigation concerning the strength of the GPC and its relation to a new parameter called the ‘Binder Index (BI)’. The parameters considered in the investigation include GGBS to fly ash ratios (0.25 0.43, 0.67, 1.0, 1.5, and 2.3) and the molarity of the alkaline activator (6, 8, 10, and 12). The binder index combines the effect of the GGBS to the fly ash ratio and the molarity of the alkaline activator. The results have shown that the strength of the GPC is significantly influenced by varying the binder index. The results indicate that a nonlinear relation exists between the binder index and the compressive strength of the GPC and the binder index and the modulus of rupture.

Mots clés

  • Geopolymer
  • Concrete
  • Strength
  • GGBS
  • Fly ash
  • Binder index
Accès libre

Quantification of Changes in the Shape and Dimensions of Parcels in Land Consolidation

Publié en ligne: 06 Apr 2019
Pages: 39 - 44

Résumé

Abstract

The paper describes the shapes and dimensions of parcels fordifferent types of land management. Firstly, various types ofland management are defined with a theoretical expression of side ratios, which should be used as a basis for drafting new parcels.In later parts of the paper, we discuss a compactness index,which is used to define the compactness of parcels and methods of calculating a compactness index by several authors. Based on the theoretical values of side ratios, we determined compactness index ranges for different types of land management. Our theoretical findings have been verified at the area of interest, i.e., part of the municipality of Stupava. Based on a comparison of the compactness index for parcels of respective owners before and after consolidation, we can evaluate any improvement of the compactness of parcels for their respective owners and, through improving the parcels’ compactness, we can improve land cultivation. Based on these calculations, we can also determine the percentage of parcels in the municipality based on side ratios before and after the consolidation process.

Mots clés

  • Land consolidation
  • Compactness
  • Compactness index
  • Shape of parcels
  • Dimensions of parcels
Accès libre

Failure of Slender Concrete Columns Due to a Loss of Stability

Publié en ligne: 06 Apr 2019
Pages: 45 - 51

Résumé

Abstract

The European standard for the design of concrete structures that are likely to lose stability requires taking into account the effects of second order theory. This effect increases the impact of a bending moment due to member deformation and additional eccentricity. Slender members can be calculated by the use of a non-linear method. This approach shows a deficit in global reliability for cases where the concrete columns fail due to the loss of stability before reaching the design resistance in the critical cross-sections. Buckling is a brittle failure which occurs without any warning, and the probability of its formation is markedly influenced by the slenderness of the column. Here, the calculation results are presented and compared with the results from an experiment which was carried out in cooperation with STRABAG Bratislava LTD at the Central Laboratory of the Faculty of Civil Engineering SUT in Bratislava. The columns were designed according to the methods stated in STN EN 1992-1-1, namely, a general non-linear method. The focus of this study is to compare multiple approaches based on codes used in Germany (DIN 1045-1, 2001) and Austria (ÖNORM B 4700, 2001) with the present European code mentioned above. The paper aims to compare the global reliability of slender concrete columns with variable slendernesses of 90 and 160.

Mots clés

  • Slender columns
  • Reliability
  • Safety factor
  • Loss of stability
Accès libre

Nature-Based Thermal Insulation Materials From Renewable Resources – A State-Of-The-Art Review

Publié en ligne: 06 Apr 2019
Pages: 52 - 59

Résumé

Abstract

In the 21st century, global climate change and the high level of fossil energy consumption have introduced changes affecting all sectors of the economy, including the building industry. Reducing energy consumption has become an important task for engineers because 30% of the total energy consumption is used for heating our buildings. Recycling the huge amount of industrial and agricultural by-products has also become urgent because due to their CO2 emissions, their combustion is not a state-of-the-art alternative. Besides rediscovering some long-known, nature-based insulating materials, there are also several research projects that have resulted in new products. In the last century it was relatively easy to review this product range, but nowadays there are so many kinds of nature-based thermal insulating products, there is a need for systematization, and more in-depth knowledge about them is required. The purpose of this paper is to develop a new systematization of nature-based thermal insulation materials, summarize the main knowledge about them, and indicate the direction of recent research and development.

Mots clés

  • Nature-Based
  • Thermal Insulation Material
  • Energy Efficiency
  • Renewable
8 Articles
Accès libre

Load – Displacement Behaviour of a Pile on a Sloping Ground for Various L/D Ratios

Publié en ligne: 06 Apr 2019
Pages: 1 - 6

Résumé

Abstract

An experimental study was carried out to understand the behaviour of a laterally loaded single pile on a slope with different length/diameter (L/D) ratios driven into cohesionless soil for a relative density of 70%. Static loading was applied in both forward and reverse directions for slopes of 1V:1.5H, 1V:2H, and 1V:2.5H for a constant L/D ratio representing flexible pile behaviour. It was observed that the load ratio (load on a sandy slope to the horizontal ground) decreased with an increase in the slope’s angle. The post-static behaviour of the pile under the same conditions was also studied to evaluate the elastic displacement, which increased with an increase in the slope’s angle. Due to the constant passive resistance under the reverse loading, the lateral load on the slope’s crest was almost equal to the horizontal ground’s condition. The effect of the L/D ratio was studied by varying the length and diameter and by maintaining the other parameter as a constant. The lateral load of a pile increased with an increase in its length and diameter.

Mots clés

  • Laterally loaded single pile
  • cohesionless soil
  • active slope
  • length to diameter ratio
  • stiffness factor
Accès libre

ADCP Discharge Measurements on the River Danube: Post-Processing and Correction of Data

Publié en ligne: 06 Apr 2019
Pages: 7 - 13

Résumé

Abstract

Accurate measurements and analyses of river discharges are one of the key tasks of hydrology. Nowadays, the traditional methods of discharge measurements are being supplemented or even replaced by novel approaches that utilize state-of-the-art technologies. One approach, which has recently become very popular in the hydrological practice both in Slovakia and abroad, is a method utilizing the Doppler effect of sound waves. In this study, a dataset of 185 discharge measurements on the River Danube was created using a RiverRay portable Acoustic Doppler Current Profiler (ADCP). All the measurements were taken on the River Danube at four different cross-sections in Slovakia. The measurements were processed using the manufacturer’s WinRiver II software and further adjusted in Agila, which is a specialised third-party post-processing software aimed at correcting measurement errors from ADCP discharge measurements. Currently, some but not all countries lying in the Danube basin have included Agila post-processing in their methodologies. This causes problems and disputes between national water authorities when exchanging information about discharge measurements in the border regions. In order to respond to this problem, the main objective of this study was to compare the results of both original and corrected discharges, which were measured under a number of different circumstances, and to propose recommendations about the suitability of using Agila post-processing for discharge measurements of the River Danube.

Mots clés

  • Discharge measurements
  • River Danube
  • ADCP
  • Agila software
  • Data post-processing
  • Doppler effect
Accès libre

Coupling Tank Model and Lars-Weather Generator in Assessments of the Impacts of Climate Change on Water Resources

Publié en ligne: 06 Apr 2019
Pages: 14 - 24

Résumé

Abstract

With the aim of assessing the impact of climate change on surface water resources, a conceptual rainfall-runoff model (the tank model) was coupled with LARS-WG as a weather generator model. The downscaled daily rainfall, temperature, and evaporation from LARS-WG under various IPCC climate change scenarios were used to simulate the runoff through the calibrated Tank model. A catchment (4648 ha) located in the southern basin of the Caspian Sea was chosen for this research study. The results showed that this model has a reasonable predictive capability in simulating minimum and maximum temperatures at a level of 99%, rainfall at a level of 93%, and radiation at a level of 97% under various scenarios in agreement with the observed data. Moreover, the results of the rainfall-runoff model indicated an increase in the flow rate of about 108% under the A1B scenario, 101% under the A2 scenario, and 93% under the B1 scenario over the 30-year time period of the discharge prediction.

Mots clés

  • Climate change
  • Impact
  • Downscaling
  • Rainfall-Runoff model
  • LARS-WG
  • Tank model
Accès libre

Characterization of Bitumen Binders on the Basis of Their Thermo-Viscous Properties

Publié en ligne: 06 Apr 2019
Pages: 25 - 31

Résumé

Abstract

Bitumen is one of the basic building materials that is mainly used in road construction. Nowadays, we can observe increased requirements for the quality of bituminous binders, which are due to increased traffic loads, changing climate conditions, and decreasing crude oil stocks. Besides “traditional” (empirical) tests (softening point, penetration), new types of tests have been developed that can better describe the quality and behavior of bitumen binders. Their composition can also be a significant part of the properties themselves. Therefore, the elemental and group composition of bitumen must also be observed. The use of the viscosity temperature susceptibility (VTS) test appears to be well suited to evaluate the properties of bitumen binders. The VTS parameter is directly dependent on the viscosity of bitumen, but it is necessary to say that VTS can be significantly affected by the composition of the bitumen. The paper is focused on determining the dependencies between the VTS and the bitumen’s composition, respectively, to find out how the composition influences the VTS.

Mots clés

  • Viscosity temperature susceptibility
  • Bitumen
  • Bitumen composition
  • Empirical tests
Accès libre

The Binder Index – A Parameter That Influences the Strength of Geopolymer Concrete

Publié en ligne: 06 Apr 2019
Pages: 32 - 38

Résumé

Abstract

Geopolymer concrete (GPC) is an environmentally friendly material in the sense that it uses industrial by-products such as ground granulated blast furnace slag (GGBS) and fly ash (FA), which are activated by an alkaline solution. This paper presents an experimental investigation concerning the strength of the GPC and its relation to a new parameter called the ‘Binder Index (BI)’. The parameters considered in the investigation include GGBS to fly ash ratios (0.25 0.43, 0.67, 1.0, 1.5, and 2.3) and the molarity of the alkaline activator (6, 8, 10, and 12). The binder index combines the effect of the GGBS to the fly ash ratio and the molarity of the alkaline activator. The results have shown that the strength of the GPC is significantly influenced by varying the binder index. The results indicate that a nonlinear relation exists between the binder index and the compressive strength of the GPC and the binder index and the modulus of rupture.

Mots clés

  • Geopolymer
  • Concrete
  • Strength
  • GGBS
  • Fly ash
  • Binder index
Accès libre

Quantification of Changes in the Shape and Dimensions of Parcels in Land Consolidation

Publié en ligne: 06 Apr 2019
Pages: 39 - 44

Résumé

Abstract

The paper describes the shapes and dimensions of parcels fordifferent types of land management. Firstly, various types ofland management are defined with a theoretical expression of side ratios, which should be used as a basis for drafting new parcels.In later parts of the paper, we discuss a compactness index,which is used to define the compactness of parcels and methods of calculating a compactness index by several authors. Based on the theoretical values of side ratios, we determined compactness index ranges for different types of land management. Our theoretical findings have been verified at the area of interest, i.e., part of the municipality of Stupava. Based on a comparison of the compactness index for parcels of respective owners before and after consolidation, we can evaluate any improvement of the compactness of parcels for their respective owners and, through improving the parcels’ compactness, we can improve land cultivation. Based on these calculations, we can also determine the percentage of parcels in the municipality based on side ratios before and after the consolidation process.

Mots clés

  • Land consolidation
  • Compactness
  • Compactness index
  • Shape of parcels
  • Dimensions of parcels
Accès libre

Failure of Slender Concrete Columns Due to a Loss of Stability

Publié en ligne: 06 Apr 2019
Pages: 45 - 51

Résumé

Abstract

The European standard for the design of concrete structures that are likely to lose stability requires taking into account the effects of second order theory. This effect increases the impact of a bending moment due to member deformation and additional eccentricity. Slender members can be calculated by the use of a non-linear method. This approach shows a deficit in global reliability for cases where the concrete columns fail due to the loss of stability before reaching the design resistance in the critical cross-sections. Buckling is a brittle failure which occurs without any warning, and the probability of its formation is markedly influenced by the slenderness of the column. Here, the calculation results are presented and compared with the results from an experiment which was carried out in cooperation with STRABAG Bratislava LTD at the Central Laboratory of the Faculty of Civil Engineering SUT in Bratislava. The columns were designed according to the methods stated in STN EN 1992-1-1, namely, a general non-linear method. The focus of this study is to compare multiple approaches based on codes used in Germany (DIN 1045-1, 2001) and Austria (ÖNORM B 4700, 2001) with the present European code mentioned above. The paper aims to compare the global reliability of slender concrete columns with variable slendernesses of 90 and 160.

Mots clés

  • Slender columns
  • Reliability
  • Safety factor
  • Loss of stability
Accès libre

Nature-Based Thermal Insulation Materials From Renewable Resources – A State-Of-The-Art Review

Publié en ligne: 06 Apr 2019
Pages: 52 - 59

Résumé

Abstract

In the 21st century, global climate change and the high level of fossil energy consumption have introduced changes affecting all sectors of the economy, including the building industry. Reducing energy consumption has become an important task for engineers because 30% of the total energy consumption is used for heating our buildings. Recycling the huge amount of industrial and agricultural by-products has also become urgent because due to their CO2 emissions, their combustion is not a state-of-the-art alternative. Besides rediscovering some long-known, nature-based insulating materials, there are also several research projects that have resulted in new products. In the last century it was relatively easy to review this product range, but nowadays there are so many kinds of nature-based thermal insulating products, there is a need for systematization, and more in-depth knowledge about them is required. The purpose of this paper is to develop a new systematization of nature-based thermal insulation materials, summarize the main knowledge about them, and indicate the direction of recent research and development.

Mots clés

  • Nature-Based
  • Thermal Insulation Material
  • Energy Efficiency
  • Renewable

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