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Zeitschriftendaten
Format
Zeitschrift
eISSN
1338-3973
ISSN
1210-3896
Erstveröffentlichung
23 May 2011
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

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

Zeitschriftendaten
Format
Zeitschrift
eISSN
1338-3973
ISSN
1210-3896
Erstveröffentlichung
23 May 2011
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

8 Artikel
access type Uneingeschränkter Zugang

Investigation of the Relation between Adhesion and Water Sensitivity Test Results

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 1 - 6

Zusammenfassung

Abstract

The relation between the results of adhesion and water sensitivity tests was investigated. The tests were performed according to the relevant European standards. Two paving grade bitumens (PGB) with different gradations were used in combination with three adhesion additives and basic, neutral and acidic coarse aggregate. It was concluded that each of the additives enhanced the evaluation of the adhesion regardless of the type of binder and aggregate. All the additives combined with PGB 35/50 improved the water sensitivity results. A better result with PGB 50/70 was observed with only one additive. It was noted that an assessment of the efficiency of an adhesion additive based on a change in the water sensitivity value (ITSR) can contradict a change in the indirect tensile strength. The expected reduction in values with an increase in the coarse aggregate acidity was only confirmed for the adhesion test. The change in the ITSR and the indirect tensile strength of dry and wet samples did not fit the expectations. The correlation between the results of the adhesion and water sensitivity test was low and could not be recommended for predicting the indirect tensile strength of asphalt from rolling bottle test results.

Schlüsselwörter

  • Binder
  • Aggregate
  • Water
  • Sensitivity
  • Adhesion
  • Additive
access type Uneingeschränkter Zugang

Physical Cavity of a Double Skin Facade as a Source of Pre-Heated Air in the Winter Season for the Heat Recovery Unit of a Facade

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 7 - 10

Zusammenfassung

Abstract

This paper deals with the use of pre-heated air in the winter season for the heat recovery unit of a facade. Heated air is transformed from solar radiation in the cavity of a double skin facade with a narrow space cavity. The height of a section is equal to one storey. With the help of mathematical modelling simulations (CFD tools), increases in temperature are quantified in the cavity of the double skin facade. The increase in temperature depends on the air flow and the intensity of the solar radiation. In conclusion, it summarizes the positive effect on heat recovery from the air exhaust to preheat a fresh supply of air from the double skin façade’s cavity. This approach can increase the efficiency of any heat recovery and reduce heat loss from the ventilation.

Schlüsselwörter

  • Heatrecovery
  • Double skin facade
  • simulation
  • CFD
  • Ansys
access type Uneingeschränkter Zugang

Utilization of Industrial Waste Products in the Production of Asphalt Concrete for Road Construction

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 11 - 17

Zusammenfassung

Abstract

The utilization of industrial waste products to produce asphalt concrete for road construction was investigated. Aggregates were partially replaced with aluminum slag (AS) and crushed ceramic tiles (CCT) at 10%, 20%, 30%, 40%, and 50% by weight. Physical tests were performed on the aggregates, while a flash and fire point test as well as penetration tests were carried out on the bitumen. Similarly, Marshall stability tests were conducted on cylindrical specimens of the asphalt concrete. The average values of 18.88 and 30.69 obtained for the aggregate impact value (AIV) and aggregate crushing value (ACV) were satisfactory for road surfacing when compared with the specification. Marshall stability values of 10.84 KN, 4.27 KN, and 3.21 KN respectively were obtained with 30%, 20%, and 50% partial replacements with AS. The percentages were suitable for heavy, medium and light traffic when compared with the Marshall design criteria provided by the Asphalt Institute. The use of aluminum slag and crushed ceramic tile could reduce the large volume of industrial waste and the cost of pavement construction and maintenance.

Schlüsselwörter

  • Non-biodegradablewaste
  • Asphalt concrete
  • Marshall stability
  • Pavement construction
  • Maintenance
access type Uneingeschränkter Zugang

Experimental Investigation and FEM Modeling of Glued Timber Connections with Slotted-In Steel Plates

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 18 - 23

Zusammenfassung

Abstract

The study is focused on the mechanical behavior and finite element method (FEM) modeling of glued timber dowel connections with slotted-in steel plates. Standard tests accompanied by a physical optics investigation method were used in order to obtain information about the mechanical properties and stress-strain behavior of glued timber dowel connections with slotted-in steel plates. As such a methodology provides information on the stress-strain state over the surface of a connection, it was used as a verification criterion for a 3D finite-element model. Small-scale glued timber dowel connections with slotted-in steel plates were tested in parallel-to-grain tension to investigate their load-carrying capacity and the load-slip performance of the connection. A three-dimensional finite-element model of the glued timber dowel connections with slotted-in steel plates was developed using existing FE software and verified using the holographic interferograms obtained during step-by-step loading as well as the test results.

Schlüsselwörter

  • Gluedtimber
  • Connections with slotted-in plates
  • Holographic laser interferometry
access type Uneingeschränkter Zugang

Application of Bioremediation Techniques as a Potent Input for the Decontamination of Bitumen-Polluted Water

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 24 - 31

Zusammenfassung

Abstract

Large deposits of natural bitumen are found in some areas of Ondo State, Nigeria. Although the mineral is still unexploited, its seepage is enough to negatively influence the environment, especially water resources. This work was designed to determine the potential of four Bitumen Utilizing Microbes (BUM) for the purification of Bitumen-Polluted Water (BPW). BUM were screened differently with a control on the BPW drawn from the affected communities. The bitumen’s degradation was determined using a supplemented enrichment medium with a sample of the BPW, and the growth was monitored by taking temperature readings, pH values, the optical density at 600 nm, and the total viable count (TVC) on days 7, 14, 21 and 28 respectively. The bitumen removal rate varied with the time of the incubation until after the third week, when the lack of nutrients supposedly set in and toxic metabolites started building up, which slowed down the process. The BUMs were identified as Bacillus firmus, Bacillus lentus, Pseudomonas aeruginosa, and Bacillus alvei. The bitumen removal trend showed that Pseudomonas aeruginosa > Bacillus firmus >Bacillus lentus > Bacillus alvei and the control the least amount of removal.

Schlüsselwörter

  • Bioremediation
  • Water
  • Pollutants
  • Pseudomonas aeruginosa
  • Removal Efficiency (RE)
access type Uneingeschränkter Zugang

Numerical Modelling of the Subsoil Zone between Stone Columns

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 32 - 39

Zusammenfassung

Abstract

Designing the improvement of soil using stone columns is usually based on simplified analytical or numerical models. Stone columns installed using a vibro-replacement technique can cause radial displacement of the original soil. It can cause radial compaction of the soil and increase the values of the strength and deformation properties, which are usually ignored in a practical design. The paper presents the results of a numerical analysis of a road embankment based on subsoil improved using stone columns. The changes in the properties of the original subsoil compacted by stone columns were analysed and taken into consideration in the models. The results showed that a model with homogenization of the subsoil and a model with stone columns transferred to continuous walls show similar results of the final settlement as well as the consolidation times. The differences between the values computed and measured were about 28 - 36 %. Taking into account the compacting effect of the original subsoil, the model with stone columns transferred to continuous walls allowed for the determination of more precise results when the difference between the values computed and measured was about 10 %.

Schlüsselwörter

  • Stonecolumns
  • Soil improvement
  • Settlement
  • Numerical modelling
access type Uneingeschränkter Zugang

Constructional Features of the Stiffness of Shearwalls in Lightweight Steel Framed Buildings

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 40 - 44

Zusammenfassung

Abstract

For low-rise buildings frame technologies using lightweight thin-wall steel constructions have become significantly widespread. The main influence on a building’s spatial rigidity under lateral forces is taken by shearwalls. The necessary stiffness can be accomplished by setting definite constructional parameters that are selected according to the design approach. The purposes of the work are to receive the dependencies of the influence of the constructional features on the stiffness of the shearwalls (using FEM models) and to set the value of the stiffness of the shearwall of any configuration by linking its parameters with the corresponding parameters of a standard shearwall through the established dependencies.

The received dependencies of the effect of the main constructional factors and design approach for the stiffness of shear-walls can be used to provide spatial rigidity. A simplified design approach for estimating the influence of the main constructional features of shearwalls on their rigidity has been developed.

Schlüsselwörter

  • Lightweight steel framing
  • Framed walls sheathed with sheets
  • Stiffness of shearwalls
  • Sheathing
  • Steel cold-formed thin gauge members
access type Uneingeschränkter Zugang

Approaches, Methods and Tools of Rights of Access to Sunlight around the World

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 45 - 52

Zusammenfassung

Abstract

Sunlight has always played an important role in the design of human settlements. Well-designed urban structures, especially in moderate or cold climates, should be assured of direct sunlight in indoor living spaces and also in public spaces. Direct sunlight in a built environment is an important factor for health and well-being, the effective functioning of solar systems, and sustainable construction. However, many problems involved in the exercise of rights of access to sunlight can arise when sunlight is obscured by a tall cityscape. Many states, regions, and cities regulate solar access, but solar rights and landowner rights are in a permanent conflict. The high urban density of many cities with tall skyscrapers accentuates the problem of the availability of sunlight. This paper presents a review of existing regulations and metrics for ensuring the availability of direct sunlight in buildings and of assessment methods that have been adopted in multiple countries and cities. Approaches, methods, and tools of rights of access to sunlight are critically analyzed. The paper also details experiences from former socialist countries where strict long-term strict on direct access to sunlight in flats were applied.

Schlüsselwörter

  • Solarrights
  • Access to sunlight
  • Urban design
  • Solar envelope
  • Owershadowing
8 Artikel
access type Uneingeschränkter Zugang

Investigation of the Relation between Adhesion and Water Sensitivity Test Results

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 1 - 6

Zusammenfassung

Abstract

The relation between the results of adhesion and water sensitivity tests was investigated. The tests were performed according to the relevant European standards. Two paving grade bitumens (PGB) with different gradations were used in combination with three adhesion additives and basic, neutral and acidic coarse aggregate. It was concluded that each of the additives enhanced the evaluation of the adhesion regardless of the type of binder and aggregate. All the additives combined with PGB 35/50 improved the water sensitivity results. A better result with PGB 50/70 was observed with only one additive. It was noted that an assessment of the efficiency of an adhesion additive based on a change in the water sensitivity value (ITSR) can contradict a change in the indirect tensile strength. The expected reduction in values with an increase in the coarse aggregate acidity was only confirmed for the adhesion test. The change in the ITSR and the indirect tensile strength of dry and wet samples did not fit the expectations. The correlation between the results of the adhesion and water sensitivity test was low and could not be recommended for predicting the indirect tensile strength of asphalt from rolling bottle test results.

Schlüsselwörter

  • Binder
  • Aggregate
  • Water
  • Sensitivity
  • Adhesion
  • Additive
access type Uneingeschränkter Zugang

Physical Cavity of a Double Skin Facade as a Source of Pre-Heated Air in the Winter Season for the Heat Recovery Unit of a Facade

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 7 - 10

Zusammenfassung

Abstract

This paper deals with the use of pre-heated air in the winter season for the heat recovery unit of a facade. Heated air is transformed from solar radiation in the cavity of a double skin facade with a narrow space cavity. The height of a section is equal to one storey. With the help of mathematical modelling simulations (CFD tools), increases in temperature are quantified in the cavity of the double skin facade. The increase in temperature depends on the air flow and the intensity of the solar radiation. In conclusion, it summarizes the positive effect on heat recovery from the air exhaust to preheat a fresh supply of air from the double skin façade’s cavity. This approach can increase the efficiency of any heat recovery and reduce heat loss from the ventilation.

Schlüsselwörter

  • Heatrecovery
  • Double skin facade
  • simulation
  • CFD
  • Ansys
access type Uneingeschränkter Zugang

Utilization of Industrial Waste Products in the Production of Asphalt Concrete for Road Construction

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 11 - 17

Zusammenfassung

Abstract

The utilization of industrial waste products to produce asphalt concrete for road construction was investigated. Aggregates were partially replaced with aluminum slag (AS) and crushed ceramic tiles (CCT) at 10%, 20%, 30%, 40%, and 50% by weight. Physical tests were performed on the aggregates, while a flash and fire point test as well as penetration tests were carried out on the bitumen. Similarly, Marshall stability tests were conducted on cylindrical specimens of the asphalt concrete. The average values of 18.88 and 30.69 obtained for the aggregate impact value (AIV) and aggregate crushing value (ACV) were satisfactory for road surfacing when compared with the specification. Marshall stability values of 10.84 KN, 4.27 KN, and 3.21 KN respectively were obtained with 30%, 20%, and 50% partial replacements with AS. The percentages were suitable for heavy, medium and light traffic when compared with the Marshall design criteria provided by the Asphalt Institute. The use of aluminum slag and crushed ceramic tile could reduce the large volume of industrial waste and the cost of pavement construction and maintenance.

Schlüsselwörter

  • Non-biodegradablewaste
  • Asphalt concrete
  • Marshall stability
  • Pavement construction
  • Maintenance
access type Uneingeschränkter Zugang

Experimental Investigation and FEM Modeling of Glued Timber Connections with Slotted-In Steel Plates

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 18 - 23

Zusammenfassung

Abstract

The study is focused on the mechanical behavior and finite element method (FEM) modeling of glued timber dowel connections with slotted-in steel plates. Standard tests accompanied by a physical optics investigation method were used in order to obtain information about the mechanical properties and stress-strain behavior of glued timber dowel connections with slotted-in steel plates. As such a methodology provides information on the stress-strain state over the surface of a connection, it was used as a verification criterion for a 3D finite-element model. Small-scale glued timber dowel connections with slotted-in steel plates were tested in parallel-to-grain tension to investigate their load-carrying capacity and the load-slip performance of the connection. A three-dimensional finite-element model of the glued timber dowel connections with slotted-in steel plates was developed using existing FE software and verified using the holographic interferograms obtained during step-by-step loading as well as the test results.

Schlüsselwörter

  • Gluedtimber
  • Connections with slotted-in plates
  • Holographic laser interferometry
access type Uneingeschränkter Zugang

Application of Bioremediation Techniques as a Potent Input for the Decontamination of Bitumen-Polluted Water

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 24 - 31

Zusammenfassung

Abstract

Large deposits of natural bitumen are found in some areas of Ondo State, Nigeria. Although the mineral is still unexploited, its seepage is enough to negatively influence the environment, especially water resources. This work was designed to determine the potential of four Bitumen Utilizing Microbes (BUM) for the purification of Bitumen-Polluted Water (BPW). BUM were screened differently with a control on the BPW drawn from the affected communities. The bitumen’s degradation was determined using a supplemented enrichment medium with a sample of the BPW, and the growth was monitored by taking temperature readings, pH values, the optical density at 600 nm, and the total viable count (TVC) on days 7, 14, 21 and 28 respectively. The bitumen removal rate varied with the time of the incubation until after the third week, when the lack of nutrients supposedly set in and toxic metabolites started building up, which slowed down the process. The BUMs were identified as Bacillus firmus, Bacillus lentus, Pseudomonas aeruginosa, and Bacillus alvei. The bitumen removal trend showed that Pseudomonas aeruginosa > Bacillus firmus >Bacillus lentus > Bacillus alvei and the control the least amount of removal.

Schlüsselwörter

  • Bioremediation
  • Water
  • Pollutants
  • Pseudomonas aeruginosa
  • Removal Efficiency (RE)
access type Uneingeschränkter Zugang

Numerical Modelling of the Subsoil Zone between Stone Columns

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 32 - 39

Zusammenfassung

Abstract

Designing the improvement of soil using stone columns is usually based on simplified analytical or numerical models. Stone columns installed using a vibro-replacement technique can cause radial displacement of the original soil. It can cause radial compaction of the soil and increase the values of the strength and deformation properties, which are usually ignored in a practical design. The paper presents the results of a numerical analysis of a road embankment based on subsoil improved using stone columns. The changes in the properties of the original subsoil compacted by stone columns were analysed and taken into consideration in the models. The results showed that a model with homogenization of the subsoil and a model with stone columns transferred to continuous walls show similar results of the final settlement as well as the consolidation times. The differences between the values computed and measured were about 28 - 36 %. Taking into account the compacting effect of the original subsoil, the model with stone columns transferred to continuous walls allowed for the determination of more precise results when the difference between the values computed and measured was about 10 %.

Schlüsselwörter

  • Stonecolumns
  • Soil improvement
  • Settlement
  • Numerical modelling
access type Uneingeschränkter Zugang

Constructional Features of the Stiffness of Shearwalls in Lightweight Steel Framed Buildings

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 40 - 44

Zusammenfassung

Abstract

For low-rise buildings frame technologies using lightweight thin-wall steel constructions have become significantly widespread. The main influence on a building’s spatial rigidity under lateral forces is taken by shearwalls. The necessary stiffness can be accomplished by setting definite constructional parameters that are selected according to the design approach. The purposes of the work are to receive the dependencies of the influence of the constructional features on the stiffness of the shearwalls (using FEM models) and to set the value of the stiffness of the shearwall of any configuration by linking its parameters with the corresponding parameters of a standard shearwall through the established dependencies.

The received dependencies of the effect of the main constructional factors and design approach for the stiffness of shear-walls can be used to provide spatial rigidity. A simplified design approach for estimating the influence of the main constructional features of shearwalls on their rigidity has been developed.

Schlüsselwörter

  • Lightweight steel framing
  • Framed walls sheathed with sheets
  • Stiffness of shearwalls
  • Sheathing
  • Steel cold-formed thin gauge members
access type Uneingeschränkter Zugang

Approaches, Methods and Tools of Rights of Access to Sunlight around the World

Online veröffentlicht: 31 Dec 2019
Seitenbereich: 45 - 52

Zusammenfassung

Abstract

Sunlight has always played an important role in the design of human settlements. Well-designed urban structures, especially in moderate or cold climates, should be assured of direct sunlight in indoor living spaces and also in public spaces. Direct sunlight in a built environment is an important factor for health and well-being, the effective functioning of solar systems, and sustainable construction. However, many problems involved in the exercise of rights of access to sunlight can arise when sunlight is obscured by a tall cityscape. Many states, regions, and cities regulate solar access, but solar rights and landowner rights are in a permanent conflict. The high urban density of many cities with tall skyscrapers accentuates the problem of the availability of sunlight. This paper presents a review of existing regulations and metrics for ensuring the availability of direct sunlight in buildings and of assessment methods that have been adopted in multiple countries and cities. Approaches, methods, and tools of rights of access to sunlight are critically analyzed. The paper also details experiences from former socialist countries where strict long-term strict on direct access to sunlight in flats were applied.

Schlüsselwörter

  • Solarrights
  • Access to sunlight
  • Urban design
  • Solar envelope
  • Owershadowing

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