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Informacje o czasopiśmie
Format
Czasopismo
eISSN
1338-3973
Pierwsze wydanie
23 May 2011
Częstotliwość wydawania
4 razy w roku
Języki
Angielski

Wyszukiwanie

Tom 30 (2022): Zeszyt 1 (March 2022)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
1338-3973
Pierwsze wydanie
23 May 2011
Częstotliwość wydawania
4 razy w roku
Języki
Angielski

Wyszukiwanie

8 Artykułów
Otwarty dostęp

Specific Design Features of Prefabricated Fire-Resistant Floor Slabs Made from Lightweight Concrete

Data publikacji: 13 Apr 2022
Zakres stron: 1 - 7

Abstrakt

Abstract

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/m3 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.

Słowa kluczowe

  • Fire
  • Fire-resistant concrete
  • Floor slabs
  • Fire resistance limits
Otwarty dostęp

A New Approach for Determining the Curvature Ductility of Reinforced Concrete Beams

Data publikacji: 13 Apr 2022
Zakres stron: 8 - 20

Abstrakt

Abstract

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.

Słowa kluczowe

  • Numericalanalysis
  • Moment-curvature
  • Ductility
  • Flexural
  • Reinforced concrete beam
  • Reinforcement
Otwarty dostęp

Theoretical Correlations Between the Cumulative Absolute Velocity and Performance Point for a Seismic Analysis of Framed Structures

Data publikacji: 13 Apr 2022
Zakres stron: 21 - 32

Abstrakt

Abstract

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-Sd) (Sd 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).

Słowa kluczowe

  • Artificial motions
  • Pushover
  • Performance
  • Harmfulness of earthquake
  • Cumulative absolute velocity
Otwarty dostęp

The Impact of Climate Change on Stochastic Variations of the Hydrology of the Flow of the Indus River

Data publikacji: 13 Apr 2022
Zakres stron: 33 - 41

Abstrakt

Abstract

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.

Słowa kluczowe

  • Multipleregression
  • Flood
  • Time series
  • SARIMA
  • Temperature
  • Rainfall
Otwarty dostęp

Numerical Study on the Effect of Water Waves and Depths on Inclined Braces with Respect to the Stability of VLFS Platforms in the Caspian Sea

Data publikacji: 13 Apr 2022
Zakres stron: 42 - 48

Abstrakt

Abstract

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.

Słowa kluczowe

  • Very Large Floating Structures (VLFS)
  • Flow 3D Model
  • Bracing Lines
  • Floating Platform
  • Horizontal Platform Displacement
Otwarty dostęp

Effecting the Rheological Properties of Composites for 3D Printing Technology in Construction

Data publikacji: 13 Apr 2022
Zakres stron: 49 - 56

Abstrakt

Abstract

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.

Słowa kluczowe

  • 3D printing
  • Technology
  • Material
  • Composite
  • Additives
  • Solidification rate
  • Structural strength
Otwarty dostęp

A 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

Data publikacji: 13 Apr 2022
Zakres stron: 57 - 66

Abstrakt

Abstract

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>0.65%), the standard deviation ratio (RSR<0.6), percent bias (±10%≤PBIAS<±15%), and the coefficient of determination (R2=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.

Słowa kluczowe

  • Catchment
  • SWAT model.
  • GIS
  • Water Yield
  • Water Balance
Otwarty dostęp

Impact of Changes in Short-Term Rainfall on Design Floods: Case Study of the Hnilec River Basin, Slovakia

Data publikacji: 13 Apr 2022
Zakres stron: 68 - 74

Abstrakt

Abstract

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.

Słowa kluczowe

  • Short-term intensities
  • CLM model
  • Burn’s vector
  • Mann-Kendal trend test
  • SCS-CN
8 Artykułów
Otwarty dostęp

Specific Design Features of Prefabricated Fire-Resistant Floor Slabs Made from Lightweight Concrete

Data publikacji: 13 Apr 2022
Zakres stron: 1 - 7

Abstrakt

Abstract

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/m3 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.

Słowa kluczowe

  • Fire
  • Fire-resistant concrete
  • Floor slabs
  • Fire resistance limits
Otwarty dostęp

A New Approach for Determining the Curvature Ductility of Reinforced Concrete Beams

Data publikacji: 13 Apr 2022
Zakres stron: 8 - 20

Abstrakt

Abstract

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.

Słowa kluczowe

  • Numericalanalysis
  • Moment-curvature
  • Ductility
  • Flexural
  • Reinforced concrete beam
  • Reinforcement
Otwarty dostęp

Theoretical Correlations Between the Cumulative Absolute Velocity and Performance Point for a Seismic Analysis of Framed Structures

Data publikacji: 13 Apr 2022
Zakres stron: 21 - 32

Abstrakt

Abstract

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-Sd) (Sd 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).

Słowa kluczowe

  • Artificial motions
  • Pushover
  • Performance
  • Harmfulness of earthquake
  • Cumulative absolute velocity
Otwarty dostęp

The Impact of Climate Change on Stochastic Variations of the Hydrology of the Flow of the Indus River

Data publikacji: 13 Apr 2022
Zakres stron: 33 - 41

Abstrakt

Abstract

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.

Słowa kluczowe

  • Multipleregression
  • Flood
  • Time series
  • SARIMA
  • Temperature
  • Rainfall
Otwarty dostęp

Numerical Study on the Effect of Water Waves and Depths on Inclined Braces with Respect to the Stability of VLFS Platforms in the Caspian Sea

Data publikacji: 13 Apr 2022
Zakres stron: 42 - 48

Abstrakt

Abstract

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.

Słowa kluczowe

  • Very Large Floating Structures (VLFS)
  • Flow 3D Model
  • Bracing Lines
  • Floating Platform
  • Horizontal Platform Displacement
Otwarty dostęp

Effecting the Rheological Properties of Composites for 3D Printing Technology in Construction

Data publikacji: 13 Apr 2022
Zakres stron: 49 - 56

Abstrakt

Abstract

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.

Słowa kluczowe

  • 3D printing
  • Technology
  • Material
  • Composite
  • Additives
  • Solidification rate
  • Structural strength
Otwarty dostęp

A 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

Data publikacji: 13 Apr 2022
Zakres stron: 57 - 66

Abstrakt

Abstract

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>0.65%), the standard deviation ratio (RSR<0.6), percent bias (±10%≤PBIAS<±15%), and the coefficient of determination (R2=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.

Słowa kluczowe

  • Catchment
  • SWAT model.
  • GIS
  • Water Yield
  • Water Balance
Otwarty dostęp

Impact of Changes in Short-Term Rainfall on Design Floods: Case Study of the Hnilec River Basin, Slovakia

Data publikacji: 13 Apr 2022
Zakres stron: 68 - 74

Abstrakt

Abstract

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.

Słowa kluczowe

  • Short-term intensities
  • CLM model
  • Burn’s vector
  • Mann-Kendal trend test
  • SCS-CN

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