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Number of results: 9
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Abstract

This paper presents an experimental analysis of flexural capacity and deformability of structural concrete slabs prepared as composite members consisting of two concrete layers made of reinforced ordinary concrete (N) and fiber reinforced concrete (SFRC). The reinforced concrete composite slabs used in the tests were prepared in the dimensions of 600 x 1200 x 80 mm. The basis was composed of two layers consisting of SFRC, one as the top layer, and one as ordinary concrete. The results of the analysis confirm a significant improvement of structural properties of the composite slab in comparison to the slabs prepared wholly of ordinary concrete.

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Authors and Affiliations

B. Sadowska-Buraczewska
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Abstract

Proper design of power installations with the participation of power cables buried in homogeneous and thermally well-conductive ground does not constitute a major problem. The situation changes when the ground is non-homogeneous and thermally low-conductive. In such a situation, a thermal backfill near the cables is commonly used. The optimization of thermal backfill parameters to achieve the highest possible current-carrying capacity is insufficiently described in the standards. Therefore, numerical calculations based on computational fluid dynamics could prove helpful for designers of power cable lines. This paper studies the influence of dimensions and thermal resistivity of the thermal backfill and thermal resistivity of the native soil on the current-carrying capacity of power cables buried in the ground. Numerical calculations were performed with ANSYS Fluent. As a result of the research, proposals were made on how to determine the current-carrying capacity depending on the dimensions and thermal properties of the backfill. A proprietary mathematical function is presented which makes it possible to calculate the cable current-carrying capacity correction factor when the backfill is used. The research is expected to fill the gap in the current state of knowledge included in the provisions of standards.
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Authors and Affiliations

Seweryn Szultka
1
ORCID: ORCID
Stanisław Czapp
1
ORCID: ORCID
Adam Tomaszewski
2
ORCID: ORCID

  1. Faculty of Electrical and Control Engineering, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
  2. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk, Poland
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Abstract

The analysis of buckling, post-buckling behaviour and load carrying capacity of prismatic composite pole structures is conducted. The asymptotic expansion established by Byskov-Hutchinson is used in the second order approximation. The thin-walled tubular columns are simply supported at the ends and subject to the uniform compression. Several types of cross-sections with and without intermediate stiffeners are considered. The present paper is the continuation of a previous paper by the authors (1999) where the modal interaction of thin-walled composite beamcolumns was investigated.
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Authors and Affiliations

Marian Królak
Zbigniew Kołakowski
Katarzyna Kowal-Michalska
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Abstract

The application of stone column technique for improvement of soft soils has attracted a considerable attention during the last decade. However, in a very soft soil, the stone columns undergo excessive bulging, because of very low lateral confinement pressure provided by the surrounding soil. The performance of stone column can be improved by the encapsulation of stone column by geosynthetic, which acts to provide additional confinement to columns, preventing excessive bulging and column failure. In the present study, a detailed experimental study on behavior of single column is carried out by varying parameters like diameter of the stone column, length of stone column, length of geosynthetic encapsulation and stiffness of encapsulation material. In addition, finite-element analyses have been performed to access the radial deformation of stone column. The results indicate a remarkable increase in load carrying capacity due to encapsulation. The load carrying capacity of column depends very much upon the diameter of the stone column and stiffness of encapsulation material. The results show that partial encapsulation over top half of the column and fully encapsulated floating column of half the length of clay bed thickness give lower load carrying capacity than fully encapsulated end bearing column. In addition, radial deformation of stone column decreases with increasing stiffness of encapsulation material.

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Authors and Affiliations

Y.K. Tandel
C.H. Solanki
A.K. Desai
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Abstract

In the present theoretical analysis, the combined effects of slider curvature and non-Newtonian pseudoplastic and dilatant lubricants (lubricant blended with viscosity index improver) on the steady and dynamic characteristics of pivoted curved slider bearings have been investigated for Rabinowitsch fluid model. The modified Reynolds equations have been obtained for steady and damping states of bearing. To solve the modified Reynolds equations, perturbation theory has been adopted. The results for the steady state characteristics (steady state film pressure, load carrying capacity and centre of pressure) and dynamic characteristics (dynamic damping and dynamic stiffness) have been calculated numerically for various values of viscosity index improver using Mathematica. In comparison with the Newtonian lubricants, higher values of film pressure, load carrying capacity, dynamic damping and dynamic stiffness have been obtained for dilatant lubricants, while the case was reversed for pseudoplastic lubricants. Significant variations in the bearing characteristics have been observed for even small values of pseudoplastic parameter, that is, with the non-Newtonian dilatant and pseudoplastic behaviour of the fluid.

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Authors and Affiliations

Udaya Pratap Singh
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Abstract

Many tourist cities face the problems regarding the social impact of short-term tourist rental. The rapid development of the tourism economy in recent years, combined with the development of digital technologies and the emergence of peer-to-peer digital platforms, has brought both positive and negative effects of the transformations. The problem is difficult and complex because the attitudes of local stakeholders vary. While residents look only through the phenomenon of gentrification and quality of life, entrepreneurs see in the short-term lease unconditional economic benefits. Cities, protecting the public interest, try to eliminate the adverse effects of tourist short-term rental in various ways. The article presents the attitudes of three groups of stakeholders in Cracow towards the phenomenon of short-term rental, namely residents, hoteliers and restaurateurs.

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Authors and Affiliations

Bartłomiej Walas
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Abstract

The study objective was to analyse the number of tourists present in the shore zone and bathing areas of lakes with regard to their tourist carrying capacity and the amount of biogenic substances potentially entering the ecosystem from the beach and bathing areas. The procedures from project between the EU and Poland, in the module “Development of the sanitary supervision of water quality” were used in three categories: physiological substances – sweat and urine; water-soluble and insoluble organic compounds; and biogenic elements – nitrogen and phosphorus. The research was conducted in two model mesotrophic lakes, Piaseczno and Zagłębocze, located in the Łęczna- Włodawa Lakeland (eastern Poland). The data were analysed in reference to biological trophic status indices defining the limnological status of lakes in the summer of 2014 and 2016. Analyses of gross primary production of phytoplankton using the light and dark bottles method and the analysis of chlorophyll a concentration were applied using the laboratory spectrophotometric method. The relatively small number of tourists recorded in the shore zone of both lakes did not exceed their tourist carrying capacity, and their potential contribution of biogenic substances to the lake ecosystems was small. Biological trophic indices for both lakes indicated that they had been continually late- mesotrophic for decades. The amount of biogenic substances directly linked to beach tourism usually has a minor effect on the limnological status of mesotrophic lakes. Due to the specific character of lake ecosystems, however, even small amounts of these substances can contribute to the destabilisation of the biocenotic system.
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Authors and Affiliations

Artur Serafin
1
ORCID: ORCID
Antoni Grzywna
1
ORCID: ORCID
Renata Augustyniak
2
ORCID: ORCID
Urszula Bronowicka-Mielniczuk
3
ORCID: ORCID

  1. University of Life Sciences in Lublin, Department of Environmental Engineering and Geodesy, Lublin, Poland
  2. University of Warmia and Mazury in Olsztyn, Department of Water Protection Engineering and Environmental Microbiology, Olsztyn, Poland
  3. University of Life Sciences in Lublin, Department of Applied Mathematics and Computer, Głęboka 28, 20-612 Lublin, Poland
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Abstract

The flexural toughness of chopped steel wool fiber reinforced cementitious composite panels was investigated. Reinforced cementitious composite panels were produced by mixing of chopped steel wool fiber with a ratio range between 0.5% to 6.0% and 0.5% as a step increment of the total mixture weight, where the cement to sand ratio was 1:1.5 with water to cement ratio of 0.45. The generated reinforced cementitious panels were tested at 28 days in terms of load-carrying capacity, deflection capacities, post-yielding effects, and flexural toughness. The inclusion of chopped steel wool fiber until 4.5% resulted in gradually increasing load-carrying capacity and deflection capacities while, provides various ductility, which would simultaneously the varying of deflection capability in the post-yielding stage. Meanwhile, additional fiber beyond 4.5% resulted in decreased maximum load-carrying capacity and increase stiffness at the expense of ductility. Lastly, the inclusion of curves gradually.
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Authors and Affiliations

Akrm A. Rmdan Amer
1
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
2
ORCID: ORCID
Yun Ming Liew
2
ORCID: ORCID
Ikmal Hakem A. Aziz
1
ORCID: ORCID
Muhammad Faheem Mohd Tahir
2
Shayfull Zamree Abd Rahim
3
ORCID: ORCID
Hetham A.R. Amer
4
ORCID: ORCID

  1. Geopolymer & Green Technology, Center of Excellence (CEGeoGTech), Universiti Malaysia Perlis (UniMAP), Perlis, Malaysia
  2. Faculty of Chemical Engineering Technology, Universiti Malaysia Perlis, Malaysia
  3. Faculty of Mechanical Engineering Technology, Universiti Malaysia Perlis (UniMAP), Perlis, Malaysia
  4. Omar Al-Mukhtar Universiti, Civil Engineering Department, Libya
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Abstract

The work includes the results of numerical, analytical-numerical and experimental study into the influence of load eccentricities with regard to major axis on post-buckling behaviour and load-carrying capacity of thin-walled cold-formed steel lipped channel section columns. The study was solved by using the finite element method (code Ansys) with taking into consideration a full material characteristics in logarithmic strain system and geometric nonlinearities. The analytical-numerical solution was based on Koiter’s theory with an application of finite difference method (FDM). Some chosen results of numerical simulations have been compared to experimental results. The deformations of columns were registered by means of Digital Image Correlation Aramis System (DICAS) to observe the maps and the magnitude of displacements for adequate point of a load. The analyses showed that the decrease in maximum load in a dependency on the eccentricity value can be even 3 times minor in a comparison to the load-carrying capacity of axially loaded column.
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Authors and Affiliations

Leszek Czechowski
1
ORCID: ORCID
Maria Kotełko
1
ORCID: ORCID
Jacek Jankowski
1
ORCID: ORCID
Viorel Ungureanu
2
ORCID: ORCID
Annabella Sanduly
1
ORCID: ORCID

  1. Lodz University of Technology, Faculty of Mechanical Engineering, Stefanowskiego 1/15 street, 90-537 Lodz, Poland
  2. Department of Steel Structures and Structural Mechanics, Politehnica University of Timisoara, Romania

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