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Abstract

The work concerns the influence of the method of numerical modelling of the connections of the roof truss and vaults with the walls of historic masonry objects structures on the local stress distribution in the walls. At the outset, the need to search for rational modelling was justified due to the large size of the calculation models and the erroneous results obtained with oversimplification of the model. Four methods of modelling the connections between the walls and roof truss and vaults were analysed. The first method was to describe the elements of walls and foundations as solid elements, the ribs of the vaults and the roof truss as beam elements, and the vaulting webs as shell elements. The remaining methods 2–4 describe the walls as shell elements. In places where the walls join with the roof truss and vaults, fictitious/fictional elements in the form of rigid horizontally-oriented shells were used in model No. 2. In model No. 3, fictitious rigid horizontally-oriented shell elements in addition to local rigid vertically-oriented shells were used, while in model No. 4, only fictitious rigid vertically-oriented shell elements with stepwise decreasing protrusions were introduced. The best solution in terms of local stress distribution turned out to be the description of connections with fictitious shell elements in the case of model No. 4. This approach slightly increases the number of unknowns, and makes the results of stresses in the connection areas realistic in relation to full modelling with solid finite elements.
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Authors and Affiliations

Czesław Miedziałowski
1
ORCID: ORCID
Marcin Szkobodziński
2
ORCID: ORCID
Krzysztof Robert Czech
1
ORCID: ORCID

  1. Bialystok University of Technology, Faculty of Civil Engineering and Environmental Sciences, Wiejska 45A, 15-351 Bialystok, Poland
  2. Energoprojekty sp. z o.o., Opolska 15, 15-549 Bialystok, Poland
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Abstract

Tension-strut systems consist of thin cables and membranes capable of carrying only tensile forces and compressed struts cooperating with them. They make very effective use of strength properties of materials. They are lightweight and common in large span structures such as bridges and stadium roofs. However, they may also be advantageous in reinforcing and repairing historical buildings as they conform to conservation law in force. This paper presents a few examples of such applications of tension-strut system. Stabilization of historic brick and stone vaults with buttresses and iron bowstrings often turns out inadequate to resist thrust forces transmitted from the vault to the walls which cause cracks and deformations of the vault. Properly designed tension-strut structure can resist the thrust forces calculated in a theoretical way. Moreover, it can be hidden in the attic of building. Old timber roof structures are usually deformed and excessively deflected. Skilfully assembled tensionstrut systems enable straightening and geometrical adjustment of a roof structure. Although similar threats and structural damages occur in most buildings which are a few hundred years old, individual design solutions are required in each case. Historical investigation and detailed measurement of geometry and deflections have to be made before choosing the apprioprate method of reinforcing the old structure.

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Authors and Affiliations

Stanisław Jurczakiewicz
ORCID: ORCID
Stanisław Karczmarczyk
ORCID: ORCID
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Abstract

The overall efficiency of a construction of a deep excavation urban project does not depend only on the duration of the construction but also on its influence on the urban environment and the traffic [9, 10]. These two things depend greatly on the excavation method and the construction stages defined during the design process. This paper describes the construction stages of three metro stations (two stations in Warsaw and one in Paris) and discusses their advantages and disadvantages including among other things its impact on neighbouring infrastructure and the city’s traffic. An important conclusion drawn from this analysis is that the shape of the slabs used can considerably affect the design and the construction stages. For example, a vaulted top slab allows an almost immediate traffic restoration and a vaulted bottom raft allows a much shorter dewatering period.
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Bibliography

[1] A. Stańczyk, “Doświadczenia z budowy stacji metra "Ratusz" i "Marymont" w Warszawie”, Inżynieria i Budownictwo, 5, pp. 244–247, 2008.
[2] Daktera, T., Bourgeois, E., Schmitt, P., Jeanmaire, T., Delva, L., & Priol, G., “Design of deep supported excavations: comparison between real behavior and predictions based on the subgrade coefficient method”, Proceedings of the XVII European Conference on Soil Mechanics and Geotechnical Engineering, pp. 2608–2615, 2019.
[3] Daktera T. “Amélioration des méthodes de calcul des écrans de soutènement à partir du retour d'expérience de grands travaux récents » PhD Thesis, Univ Gustave Eiffel, (to be published) 2020.
[4] M. Graff, “Subway in Warsaw”, Transport systems, 12, pp. 25–35, 2018.
[5] K.F. Unrug, “Shaft design criteria”, International Journal of Mining Engineering, 2, 141–155, 1984.
[6] ILF CONSULTING ENGINEERS, “Design and construction of the underground line II from “Rondo Daszyńskiego” station to the “DworzecWileński” station in Warsaw”, 2010.
[7] M. Mitew-Czajewska, “Geotechnical investigation and static analysis of deep excavation walls – a case study of metro station construction in Warsaw”, Ann. Warsaw Univ. Life Sci. – SGGW, Land Reclam. 47 (2), pp. 163–171, 2015. http://doi.org/10.1515/sggw-2015-0022
[8] A. Sieminska-Lewandowska, “Budowa obiektu a obudowa wykopu – niełatwe zależności”, Nowoczesne Budownictwo Inżynieryjne, marzec kwiecień, pp. 64–71, 2010.
[9] A. Siemińska-Lewandowska, “Głębokie wykopy. Projektowanie i wykonawstwo.”, WKŁ, Warszawa, 2010.
[10] G. Kacprzak, S. Bodus, “The modelling of excavation protection in a highly urbanised environment”, Technical Transactions, Vol. 1, pp. 133–142, 2019. https://doi.org/10.4467/2353737XCT.19.009.10049
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Authors and Affiliations

Grzegorz Kacprzak
1
ORCID: ORCID
Tomasz Daktera
2
ORCID: ORCID
Andrzej Stańczyk
3
ORCID: ORCID
Urszula Tomczak
1
ORCID: ORCID
Seweryn Bodus
3
ORCID: ORCID
Michał Werle
3
ORCID: ORCID

  1. Warsaw University of Technology, Faculty of Civil Engineering, Al. Armii Ludowej 16, 00-637 Warsaw, Poland
  2. Soletanche Bachy International 280 Avenue Napoléon Bonaparte, 92500 Rueil Malmaison, France
  3. Warbud S.A.

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