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Number of results: 6
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Abstract

Polar snow and its accumulation preserve valuable information derived from the atmosphere on past climate and environmental changes in high resolution, particularly in coastal sites. A 2.5-m snow-pit was excavated from the coastal ice rise (Moore Dome) near Amundsen Sea region in February 2012. This study evaluated the isotopic and chemical compositions in the snow-pit and compared them with meteorological variables. Based on the seasonal peaks of the MSA and nssSO42– together with 18O, D, and d-excess, the snow-pit record was corresponded to accumulation during austral winter 2011 to summer 2011/2012. The annual mean accumulation rate was assumed thus to be as large as or even higher than 1.03 m w.e. yr–1 at this site. A relatively warm winter temperature in 2011 was traceable in the variations of 18O, D, and d-excess. This study emphasizes the importance of the high snow accumulation observed at this site in providing valuable information on sub-annual variations in climate and environmental changes through the study of longer ice cores.
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Authors and Affiliations

Sang-Bum Hong
1
ORCID: ORCID
Yalalt Nyamgerel
2
ORCID: ORCID
Won Sang Lee
1
ORCID: ORCID
Jeonghoon Lee
2
ORCID: ORCID

  1. Division of Glacial Environment Research, Korea Polar Research Institute, 26, Songdomirae-ro, Yeonsu-gu, Incheon 21990, Korea
  2. Department of Science Education, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Korea
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Abstract

The structural concept of the dome dates back to the Pantheon in Rome. It is used as the cover of many churches and mosques all around the world. Light solutions, with a well-visible dome-shaped truss skeleton, are often preferred in modern architecture. Base isolation techniques can be adopted to mitigate the seismic effects. This paper aims to investigate the efficiency of different designs for the truss skeleton. To solve the problem, one has to assign the constraints, the materials and the geometry of the dome, its supporting structure and the isolation devices (number, locations, and type). The screening of the effects of different scheme assumptions on structural behaviour provides a better insight into the problem.
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Authors and Affiliations

Sara Casciati
1
ORCID: ORCID

  1. SIART srl, Pavia, Italy
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Abstract

In this paper, the dynamic behaviour of the tensegrity domes is explored. The consideration includes all cable structures called Geiger domes, i.e., two cases of configurations (with a closed and open upper section) and two variants of the nature of a dome (regular and modified) are taken into account. Particularly, the impact of the number of girders on the natural frequencies is analysed. A geometrically quasi-linear model is used, implemented in an original program written in the Mathematica environment. The results confirmthat the number of girders affects the number of infinitesimal mechanisms. However, the dynamic behaviour does not depend on the number of mechanisms. The most important is the nature of a dome and the type of load-bearing girder. Especially, the behaviour of Geiger domes with a closed upper section is specific. In this case, not only the frequencies corresponding to the infinitesimal mechanisms depend on the prestress. There are additional frequencies that depend on prestress. The number of them, and the sensitivity on the initial prestress changes, depends on the number of girders. Generally, for the same number of girders, the natural frequencies of regular domes are higher than for the modified ones.
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Authors and Affiliations

Paulina Obara
1
ORCID: ORCID
Maryna Solovei
1
ORCID: ORCID

  1. Kielce University of Technology, Faculty of Civil Engineering, Al. Tysiaclecia Panstwa Polskiego 7, 25-314 Kielce, Poland
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Abstract

The paper presents the determination of the impact of earthquakes of varying intensity on the structure of geodesic domes. The structures of the analyzed domes were designed on the basis of the regular octahedron according to two different methods of creating their topology. The use of four seismic records of different intensity and duration of the record made it possible to subject 8 models to numerical analysis. The designed spatial structures are domes with a steel cross-section, thanks to which they are undoubtedly characterized by their lightness and the possibility of covering very large areas, without the need to use internal supports. Designing steel domes is currently a challenge for constructors, as well as architect, who take into account their aesthetic considerations. The paper presents the seismic response of geodesic domes in applied different directions (two horizontal “X” and “Y” and one vertical “Z”), using the Time History method. The values of forced vibrations and recording intensity were shown, and on this basis, an attempt was made to determine which seismic record may be more unfavorable for the designed geodesic domes created according to two different methods of shaping the topology of their structures. For this purpose, the FFT (Fast Fourier Transform) method was used. The maximum accelerations and displacements of the structures were also analyzed. The conducted analysis shows the influence of seismic excitations on geodetic dome structures, depending on the applied method (method 1 and 2) of shaping their topology. This paper will undoubtedly be useful in designing a geodesic dome structure in a seismic area. In addition, this analysis can be helpful in assessing the effects of an incidental earthquake.
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Authors and Affiliations

Dominika Bysiec
1
ORCID: ORCID
Tomasz Maleska
1
ORCID: ORCID

  1. Opole University of Technology, Faculty of Civil Engineering and Architecture
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Abstract

The paper concerns steel domes with regard to the special structures named tensegrity. Tensegrities are characterized by the occurrence of self-stress states. Some of them are also characterized by the presence of infinitesimal mechanisms. The aim of this paper is to prove that only tensegrity domes with mechanisms are sensitive to the change of the level of initial prestress. Two tensegrity domes are considered. In addition, a standard single-layer dome is taken into account for comparison. The analysis is carried out in two stages. Firstly, the presence of the characteristic tensegrity features is examined (qualitative analysis). Next, the behavior under static external loads is studied (quantitative analysis). In particular, the influence of the initial prestress level on displacements, effort, and stiffness of the structure is analyzed. To evaluate this behavior, a geometrically non-linear model is used. The model is implemented in an original program written in the Mathematica environment. The analysis demonstrates that for a dome with mechanisms, the adjustment of pre-stressing forces influences the static properties. It has been found that the stiffness depends not only on the geometry and properties of the material but also on the initial prestress level and external load. In the case of the non-existence of mechanisms, structures are insensitive to the initial prestress level.
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Authors and Affiliations

Paulina Obara
1
ORCID: ORCID
Maryna Solovei
1
ORCID: ORCID
Justyna Tomasik
1
ORCID: ORCID

  1. Faculty of Civil Engineering and Architecture, Kielce University of Technology, Poland

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