Zeitschriften und Ausgaben

Volumen 30 (2022): Heft 2 (June 2022)

Volumen 30 (2022): Heft 1 (March 2022)

Volumen 29 (2021): Heft 4 (December 2021)

Volumen 29 (2021): Heft 3 (September 2021)

Volumen 29 (2021): Heft 2 (June 2021)

Volumen 29 (2021): Heft 1 (March 2021)

Volumen 28 (2020): Heft 4 (December 2020)

Volumen 28 (2020): Heft 3 (September 2020)

Volumen 28 (2020): Heft 2 (June 2020)

Volumen 28 (2020): Heft 1 (March 2020)

Volumen 27 (2019): Heft 4 (December 2019)

Volumen 27 (2019): Heft 3 (September 2019)

Volumen 27 (2019): Heft 2 (June 2019)

Volumen 27 (2019): Heft 1 (March 2019)

Volumen 26 (2018): Heft 4 (December 2018)

Volumen 26 (2018): Heft 3 (September 2018)

Volumen 26 (2018): Heft 2 (June 2018)

Volumen 26 (2018): Heft 1 (March 2018)

Volumen 25 (2017): Heft 4 (December 2017)

Volumen 25 (2017): Heft 3 (September 2017)

Volumen 25 (2017): Heft 2 (June 2017)

Volumen 25 (2017): Heft 1 (March 2017)

Volumen 24 (2016): Heft 4 (December 2016)

Volumen 24 (2016): Heft 3 (September 2016)

Volumen 24 (2016): Heft 2 (June 2016)

Volumen 24 (2016): Heft 1 (March 2016)

Volumen 23 (2015): Heft 4 (December 2015)

Volumen 23 (2015): Heft 3 (September 2015)

Volumen 23 (2015): Heft 2 (June 2015)

Volumen 23 (2015): Heft 1 (March 2015)

Volumen 22 (2014): Heft 4 (December 2014)

Volumen 22 (2014): Heft 3 (September 2014)

Volumen 22 (2014): Heft 2 (June 2014)

Volumen 22 (2014): Heft 1 (March 2014)

Volumen 21 (2013): Heft 4 (December 2013)

Volumen 21 (2013): Heft 3 (September 2013)

Volumen 21 (2013): Heft 2 (June 2013)

Volumen 21 (2013): Heft 1 (March 2013)

Volumen 20 (2012): Heft 4 (December 2012)

Volumen 20 (2012): Heft 3 (September 2012)

Volumen 20 (2012): Heft 2 (June 2012)

Volumen 20 (2012): Heft 1 (March 2012)

Volumen 19 (2011): Heft 4 (December 2011)

Volumen 19 (2011): Heft 3 (September 2011)

Volumen 19 (2011): Heft 2 (June 2011)

Volumen 19 (2011): Heft 1 (March 2011)

Volumen 18 (2010): Heft 4 (December 2010)

Volumen 18 (2010): Heft 3 (September 2010)

Volumen 18 (2010): Heft 2 (June 2010)

Volumen 18 (2010): Heft 1 (March 2010)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1338-3973
Erstveröffentlichung
23 May 2011
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 29 (2021): Heft 1 (March 2021)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1338-3973
Erstveröffentlichung
23 May 2011
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

7 Artikel
access type Uneingeschränkter Zugang

Effect of the Temperature on the Modal Properties of a Steel Railroad Bridge

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 1 - 8

Zusammenfassung

Abstract

The article is devoted to a study of the impact of various environmental conditions on modal parameters, such as natural frequencies and damping ratios. The modal analysis has been performed using the Stochastic Subspace Identification (SSI) method of measuring data every month on the same steel bridge structures located on an important railroad route from Prague (the Czech Republic) to Košice (Slovakia). The structure is approximately 60 m long, and the bearing structure is formed by two arch trusses. The bridge was exposed to ambient vibrations as well as to vibrations caused by a train passage. Accelerations and temperatures (the temperature of the air and the structure) were logged during the measurements. Natural frequencies were obtained from these acceleration data using the SSI method and processed into graphs of the dependencies between the natural frequencies and temperatures. Some statistical procedures were also applied.

Schlüsselwörter

  • Modalanalysis
  • Structural health monitoring
  • Steel bridge
  • Natural frequency
  • System identification
  • Temperature
access type Uneingeschränkter Zugang

Analysis of a Topsoil Moisture Regime Through an Effective Precipitation Index for the Locality of Nitra, Slovakia

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 9 - 14

Zusammenfassung

Abstract

The aim of this work was to analyze and statistically confirm the relationship between the computed daily values of the Effective Precipitation Index (EP365) and the measured moisture content of the topsoil of a research site near Nitra, Slovakia. The statistical analysis (coefficients of determination) confirmed the strong correlation. Subsequently each day’s mean of EP365 (MEP) was used to quantify the long-term deficit or surplus of the soil water supply in the individual years. The daily values of the EP365 index provide a more detailed view of the development of the topsoil’s moisture regime. According to the deviation of EP (DEP) from the 14-year MEP, the most extreme dry periods prevailed during the years 2015, 2017 and 2018. Therefore, the 2012–2018period was evaluated as dry, and the topsoil moisture regime described through the MEP index was compared with the course of the MEP index from the normal (slightly humid) period of the years 2005 – 2011.

Schlüsselwörter

  • Meteorologicalindices
  • Soil moisture regime
  • Droughts
  • Effective Precipitation Index
access type Uneingeschränkter Zugang

Sound Absorption Properties of Materials Based on Recycled Plastic Granule Mixtures

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 15 - 19

Zusammenfassung

Abstract

This article reports on impedance tube measurements of the sound absorption coefficient α (-) of selected recycled foam plastics, i.e., ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP), in different mixtures with a binding adhesive. The effect of the thickness of the sample on the sound absorption spectrum as well as the variability in absorption across the different samples of the same composition and thickness are discussed. For the EVA/ PP and PS/PP mixtures, the spectrum is characterized by two peaks that shift as the thickness is changing. These mixtures were also found to be the most absorbent across the whole audible frequency range.

Schlüsselwörter

  • Soundabsorption
  • Recycling
  • Metamaterials
access type Uneingeschränkter Zugang

Simulation Modelling of Aerial Works and Its Role in the Preparation of Construction

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 20 - 26

Zusammenfassung

Abstract

The construction process is characterized by a diverse technological composition and the use of a wide range of construction machinery and mechanization. The amount of machinery increases with the complexity of the construction, which increases the demands concerning the preparation and overall organisation of the construction. The preparation of construction processes carried out by helicopters (aerial work) must respect the effect of randomly changing construction conditions as well as the specific working conditions of helicopters. The complexity of such a system can be modelled using simulation models. In the work presented, we designed and practically tested a simulation model of aerial work in the MATLAB software environment. An essential part of the simulation model is an algorithm designed on the basis of commercial numerical weather prediction models. We consider the outputs of the simulation to be reliable, because they are very close to the actual results achieved in the case of the implementation of construction of this type. The concept of the simulation model enables its wider use not only in the construction sector, but also in other branches of industry.

Schlüsselwörter

  • Simulationmodel
  • Helicopter
  • Construction processes
  • Pre-construction design
  • Numerical weather prediction
  • Logistics
access type Uneingeschränkter Zugang

Evaluation of the Cohesive Properties of SBS-Modified Binders at Low Temperatures

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 27 - 34

Zusammenfassung

Abstract

The durability, fatigue resistance, and low-temperature behavior of asphalt layers are greatly affected by the properties of bitumen. Therefore, the composition of bitumen is frequently modified to improve the performance of asphalt mixtures. Sty-rene-butadiene-styrene (SBS) has been the most often used additive recently. Researchers are trying to improve the cohesive and adhesive properties of binders by such polymer-based additives. In this study, 160/220 penetration grade bitumen and Kraton D 1101 SBS were used. The present study contains a new evaluation for determining the cohesive behavior of SBS-modified binders at -1°C, -3°C, and -5°C. The results of this evaluation were compared to conventional and rheological test results. Penetration, softening point, viscosity, dynamic shear rheometer, and bending beam rheometer tests were therefore conducted. Finally, the results of a low-temperature tensile test were found to be consistent with the results of the other tests; hence, they also confirm the cohesive behavior of SBS-modified binders at low temperatures.

Schlüsselwörter

  • Bitumen
  • Cohesion
  • SBS
  • Modification
  • Low temperature
access type Uneingeschränkter Zugang

Effects of Interference on Local Peak Pressures Between Two Buildings with an Elliptical Cross-Section

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 35 - 41

Zusammenfassung

Abstract

The interference effects on the distribution of external wind pressure coefficient between two high-rise buildings with an elliptical cross section were studied experimentally at the Boundary Layer Wind Tunnel (BLWT) at the Faculty of Civil Engineering STU in Bratislava, Slovakia. Various arrangements of models, which were derived from the breadth ratio, were investigated. The peak value of the external wind pressure coefficient for a stand-alone model was measured and compared with the peak value in the case of interference. The measurements showed that the wind loads on buildings in a close vicinity are considerably different from those on a stand-alone building. The interference effects significantly affect negative pressure zones. The optimal and critical arrangements of buildings were evaluated. The elimination of peak negative external wind pressure coefficients can be reduced by half. On the other hand, the interference effects had a strong impact on increasing the peak value of the negative external wind pressure coefficient, which can be more than roughly double compared to an isolated building.

Schlüsselwörter

  • Effects of interference
  • Wind tunnel
  • External wind pressure coefficient
  • Elliptical high-rise building
access type Uneingeschränkter Zugang

Thermaly Active Interior Panels with an Integrated Active Area

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 42 - 47

Zusammenfassung

Abstract

Panels with an integrated active area can be used for interior applications for walls, ceilings and floor heating, and alternatively as a wet or dry type of construction. At present, most panels with an integrated active area are made of gypsum boards with milled channels and embedded pipes. Some manufacturers already supply these panels with thermal insulation (Radwan et al., 2021; Zhang et al., 2020). Certain limitations, mainly regarding the diameter and material of the pipes, apply to the panels with channels milled in the gypsum board and embedded pipes. These limitations are closely related to the high cost of such panels and to the limited heat/cooling output. The disadvantages of these panels are eliminated by the construction of a thermal insulation panel with active thermal protection for application with an active heat transfer control system (indoor thermally active panel (ITAP)) in accordance with European Patent No. EP 2 572 057 B1 (Kalús, 2011).

Schlüsselwörter

  • Indoor thermally active panels (ITAP)
  • Active heating/cooling surface
7 Artikel
access type Uneingeschränkter Zugang

Effect of the Temperature on the Modal Properties of a Steel Railroad Bridge

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 1 - 8

Zusammenfassung

Abstract

The article is devoted to a study of the impact of various environmental conditions on modal parameters, such as natural frequencies and damping ratios. The modal analysis has been performed using the Stochastic Subspace Identification (SSI) method of measuring data every month on the same steel bridge structures located on an important railroad route from Prague (the Czech Republic) to Košice (Slovakia). The structure is approximately 60 m long, and the bearing structure is formed by two arch trusses. The bridge was exposed to ambient vibrations as well as to vibrations caused by a train passage. Accelerations and temperatures (the temperature of the air and the structure) were logged during the measurements. Natural frequencies were obtained from these acceleration data using the SSI method and processed into graphs of the dependencies between the natural frequencies and temperatures. Some statistical procedures were also applied.

Schlüsselwörter

  • Modalanalysis
  • Structural health monitoring
  • Steel bridge
  • Natural frequency
  • System identification
  • Temperature
access type Uneingeschränkter Zugang

Analysis of a Topsoil Moisture Regime Through an Effective Precipitation Index for the Locality of Nitra, Slovakia

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 9 - 14

Zusammenfassung

Abstract

The aim of this work was to analyze and statistically confirm the relationship between the computed daily values of the Effective Precipitation Index (EP365) and the measured moisture content of the topsoil of a research site near Nitra, Slovakia. The statistical analysis (coefficients of determination) confirmed the strong correlation. Subsequently each day’s mean of EP365 (MEP) was used to quantify the long-term deficit or surplus of the soil water supply in the individual years. The daily values of the EP365 index provide a more detailed view of the development of the topsoil’s moisture regime. According to the deviation of EP (DEP) from the 14-year MEP, the most extreme dry periods prevailed during the years 2015, 2017 and 2018. Therefore, the 2012–2018period was evaluated as dry, and the topsoil moisture regime described through the MEP index was compared with the course of the MEP index from the normal (slightly humid) period of the years 2005 – 2011.

Schlüsselwörter

  • Meteorologicalindices
  • Soil moisture regime
  • Droughts
  • Effective Precipitation Index
access type Uneingeschränkter Zugang

Sound Absorption Properties of Materials Based on Recycled Plastic Granule Mixtures

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 15 - 19

Zusammenfassung

Abstract

This article reports on impedance tube measurements of the sound absorption coefficient α (-) of selected recycled foam plastics, i.e., ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP), in different mixtures with a binding adhesive. The effect of the thickness of the sample on the sound absorption spectrum as well as the variability in absorption across the different samples of the same composition and thickness are discussed. For the EVA/ PP and PS/PP mixtures, the spectrum is characterized by two peaks that shift as the thickness is changing. These mixtures were also found to be the most absorbent across the whole audible frequency range.

Schlüsselwörter

  • Soundabsorption
  • Recycling
  • Metamaterials
access type Uneingeschränkter Zugang

Simulation Modelling of Aerial Works and Its Role in the Preparation of Construction

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 20 - 26

Zusammenfassung

Abstract

The construction process is characterized by a diverse technological composition and the use of a wide range of construction machinery and mechanization. The amount of machinery increases with the complexity of the construction, which increases the demands concerning the preparation and overall organisation of the construction. The preparation of construction processes carried out by helicopters (aerial work) must respect the effect of randomly changing construction conditions as well as the specific working conditions of helicopters. The complexity of such a system can be modelled using simulation models. In the work presented, we designed and practically tested a simulation model of aerial work in the MATLAB software environment. An essential part of the simulation model is an algorithm designed on the basis of commercial numerical weather prediction models. We consider the outputs of the simulation to be reliable, because they are very close to the actual results achieved in the case of the implementation of construction of this type. The concept of the simulation model enables its wider use not only in the construction sector, but also in other branches of industry.

Schlüsselwörter

  • Simulationmodel
  • Helicopter
  • Construction processes
  • Pre-construction design
  • Numerical weather prediction
  • Logistics
access type Uneingeschränkter Zugang

Evaluation of the Cohesive Properties of SBS-Modified Binders at Low Temperatures

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 27 - 34

Zusammenfassung

Abstract

The durability, fatigue resistance, and low-temperature behavior of asphalt layers are greatly affected by the properties of bitumen. Therefore, the composition of bitumen is frequently modified to improve the performance of asphalt mixtures. Sty-rene-butadiene-styrene (SBS) has been the most often used additive recently. Researchers are trying to improve the cohesive and adhesive properties of binders by such polymer-based additives. In this study, 160/220 penetration grade bitumen and Kraton D 1101 SBS were used. The present study contains a new evaluation for determining the cohesive behavior of SBS-modified binders at -1°C, -3°C, and -5°C. The results of this evaluation were compared to conventional and rheological test results. Penetration, softening point, viscosity, dynamic shear rheometer, and bending beam rheometer tests were therefore conducted. Finally, the results of a low-temperature tensile test were found to be consistent with the results of the other tests; hence, they also confirm the cohesive behavior of SBS-modified binders at low temperatures.

Schlüsselwörter

  • Bitumen
  • Cohesion
  • SBS
  • Modification
  • Low temperature
access type Uneingeschränkter Zugang

Effects of Interference on Local Peak Pressures Between Two Buildings with an Elliptical Cross-Section

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 35 - 41

Zusammenfassung

Abstract

The interference effects on the distribution of external wind pressure coefficient between two high-rise buildings with an elliptical cross section were studied experimentally at the Boundary Layer Wind Tunnel (BLWT) at the Faculty of Civil Engineering STU in Bratislava, Slovakia. Various arrangements of models, which were derived from the breadth ratio, were investigated. The peak value of the external wind pressure coefficient for a stand-alone model was measured and compared with the peak value in the case of interference. The measurements showed that the wind loads on buildings in a close vicinity are considerably different from those on a stand-alone building. The interference effects significantly affect negative pressure zones. The optimal and critical arrangements of buildings were evaluated. The elimination of peak negative external wind pressure coefficients can be reduced by half. On the other hand, the interference effects had a strong impact on increasing the peak value of the negative external wind pressure coefficient, which can be more than roughly double compared to an isolated building.

Schlüsselwörter

  • Effects of interference
  • Wind tunnel
  • External wind pressure coefficient
  • Elliptical high-rise building
access type Uneingeschränkter Zugang

Thermaly Active Interior Panels with an Integrated Active Area

Online veröffentlicht: 13 Apr 2021
Seitenbereich: 42 - 47

Zusammenfassung

Abstract

Panels with an integrated active area can be used for interior applications for walls, ceilings and floor heating, and alternatively as a wet or dry type of construction. At present, most panels with an integrated active area are made of gypsum boards with milled channels and embedded pipes. Some manufacturers already supply these panels with thermal insulation (Radwan et al., 2021; Zhang et al., 2020). Certain limitations, mainly regarding the diameter and material of the pipes, apply to the panels with channels milled in the gypsum board and embedded pipes. These limitations are closely related to the high cost of such panels and to the limited heat/cooling output. The disadvantages of these panels are eliminated by the construction of a thermal insulation panel with active thermal protection for application with an active heat transfer control system (indoor thermally active panel (ITAP)) in accordance with European Patent No. EP 2 572 057 B1 (Kalús, 2011).

Schlüsselwörter

  • Indoor thermally active panels (ITAP)
  • Active heating/cooling surface

Planen Sie Ihre Fernkonferenz mit Scienceendo