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Archiv článků od 8.3.2021 do 17.5.2021

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17.5.2021
doc. Dr. Ing. Jan Pruška, Ing. Veronika Pavelcová

Eurocode 1998-5 for the design of earth retaining structures in seismic conditions describes calculation using the Mononobe-Okabe method. This simplified quasi-static procedure is partly very conservative. The article describes the limits of this method, comparison with other approaches in American NHCRP 661 and Chen and Liu method.

16.5.2021
Ing. Michal Brandtner, Ing. Adam Boháček

The article deals with the data structure for the purpose of Life Cycle Assessment (LCA) of buildings using the Building Information Model (BIM). LCA is a method that can be used to demonstrate the suitability of proposed materials, structures, or buildings in terms of their whole life cycle and its environmental impact. For the LCA evaluation it is crucial to obtain life cycle inventory (LCI) input data. The aim of the article is to define a BIM data structure for LCI purposes. The new methodology is based on standardization of non-graphic information model data structure called SNIM. Advantages of the proposed methodology have been demonstrated on the case study. These results are useful for expanding the BIM model with new data necessary for further LCA calculations.

ilustrační foto © MIakov Kalinin - Fotolia.com
10.5.2021
Ing. Daniel Kliment, VUT v Brně, Ústav soudního inženýrství

The paper focuses on the study of the relationship between housing prices and selected environmental characteristics, the impact of the perception of urban scenes near residential real estate on the price of housing and presents the results of known and already performed studies. Introduced characteristics of urban scene perception are often combined with other traditional characteristics, for example in the hedonic pricing model for calculating marginal prices, another alternative method is to use expert judgment, for example for hedonic analysis. The performed studies develop and form quantification tools, which subsequently help people in decision-making processes to understand and analyze the interactions between residents and individual components of urban scenes and urbanism.

10.5.2021
doc. Ing. Karel Vojtasík, CSc., VŠB TU Ostrava, FAST, katedra Geotechniky a podzemního stavitelství

The determination of the bearing capacity of the micropile from the tensile bearing capacity is based on a comparison of the results of compressive and tensile loading tests of micropiles, which were performed on an external test load frame. The micropiles were first tested with compressive forces and later after about one year the same micropiles were tested with tensile forces. Four grouted micropiles with a length of 3 m, which were installed in loess clays, were tested. The result of the tests are graphs of the dependence of the settlement and extraction of the micropile on the applied forces. These graphs are compared and it is looked for a dependency that would make possible an estimation of the bearing capacity of a micropile in compression from the tensile test.

3.5.2021
Ing. Ondřej Anton, Ph.D., doc. Ing. Petr Cikrle, Ph.D., Ing. Věra Heřmánková, Ph.D.

The field of diagnosis of structures has been experiencing a dynamic development in the last decades caused by the development and expansion of new NDT methods and instrumentation. At the same time, it is possible to observe changes in the focus of interest in this field, or more precisely, alternating waves of interest in specific types of diagnosis targeted at special types of structures. These waves of interest are always caused by a certain trend in the development of the society or building industry, and most often, by some major even in the field. In the last few years, particular attention has been paid to prestressed structures, especially to bridges, in connection with the recent accidents of bridges made from prestressed concrete in the Czech Republic and abroad. Considering the relatively large number of these bridges in the Czech Republic built in the second half of the 20th century, attention is paid to basic changes in the pre-construction condition surveys aimed at determining the condition and the remaining life of these structures. The paper focuses on the analysis of possibilities of assessing the condition of prestressing steel at the level of the present state of diagnosis of structures.

ilustrační foto: Main Point Karlín © TZB-info
30.4.2021
Ing. Zuzana Mrňová, VUT FAST Brno, Ústav stavební ekonomiky a řízení

A responsible approach to the environment is not only related to corporate ecology, but is also increasingly reflected in the design and construction of buildings, which is closely related to the concept of sustainable construction of buildings. With the development of sustainable construction, the need arose to evaluate buildings and their impact on the environment. For this reason, environmental certifications of buildings have been developed, which assess how a building affects its surroundings during its life cycle.
The aim of this article is to find out which environmental certifications exist in the world and which of them are most often used in the Czech Republic. Finally, the certifications are compared and their main differences are described.

26.4.2021
Ing. Lucia Ondrušková, Slovenská technická univerzita, Stavebná fakulta, Katedra kovových a drevených konštrukcií

Increased stresses occur near the supports of glass structures, which can be decisive for design of glass member. Recommendations for minimum distance of bolted connection from the edge can be found in current standarts. For verification of details are used FE-models. Influence of the edge distance and material thickness on the maximum stress value at the edge of the hole in glass loaded in its plane is compared in this paper.

19.4.2021
Ing. Kristina Fořtová, Ph.D., Ing. Diana Mariaková, Ing. Jakub Řepka, Ing. Tereza Pavlů, Ph.D.

This article deals with the possibility of using masonry aggregate from construction and demolition waste. The article summarizes the properties of concrete with a laboratory-optimized recipe with a full replacement of natural aggregate with recycled masonry aggregate. Testing of concrete samples was carried out according to valid standards. The result is a mixture with optimized properties for the production of construction parts.

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19.4.2021
prof. Ing. Ivan Vaníček, DrSc., Ing. Daniel Jirásko, Ph.D.

Very quick process of digitalization in civil engineering is progressing also in the branch of geotechnical engineering. BIM is a part of this process. Mutual interconnection of the 3D model of ground with the 3D model of the geotechnical structure can help to give more clear view on the interaction of this structure with ground. However, at the same time it makes possible better control for all participants of the construction process, particularly if all conditions of this mutual interaction are fulfilled. Whether the main aim of the construction process – that the care devoted to the individual phases of the structure design and execution correspond to the risk with which this structure and ground are connected. Within this context a closer specification of the Eurocode 7 of the second generation will be specified, as it counts with different models.

18.4.2021
Ing. Lubomír Petrula, VUT FAST Brno, Ústav vodního hospodářství obcí

Internal erosion is one of the most common causes of failure of hydraulic structures. A special case is a backward erosion piping during which an exceeding of critical hydraulic gradient occurs on the edge of the structure foundation interface. This becomes especially dangerous for the structure when the foundation consists of sand or very sandy soil that is very easy to erode. The sand property of erodibility is not yet fully described. In this paper, an experimental device used for the rate of erosion determination for a picked sand is presented as well as a calculation of the erosion coefficient which is usually used to describe soil erodibility. Furthermore, the paper contains critical hydraulic gradients during which the erosion occurred.

13.4.2021
Ing. David Průša, prof. RNDr. Ing. Stanislav Šťastník, CSc., Ph.D., doc. Ing. Karel Šuhajda, Ph.D.

This task deals with the properties and the possibility of recycling of thermal insulation materials such as polystyrene and mineral wool, not only from buildings after demolition but also from discarded materials left over after the construction of new buildings. This newly developed material is being tested as a filler for ultra-lightweight concrete where it fills the cavities of ceramic hollow bricks, as a filler for self-compacting concrete (SCC) and for the production of acoustic facing.

12.4.2021
prof. Ing. Peter Turček, PhD., Stavená fakulta STU, Bratislava, Katedra geotechniky

The paper offers an overview of the performed analyses, which evaluated the leakage into underground garages in the densely built-up area of the Prague city centre. Only after a comprehensive reassessment of geological conditions, the project and other available information was it possible to determine the probable causes of leakage into large underground parking spaces.

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29.3.2021
Ing. Peter Kyselica, Ing. Patrik Ševčík

The aim of the paper is to summarize and evaluate individual diagnostic procedures that diagnose reinforced concrete structures damaged by fire. Based on our experience, we tried to design a methodology for the selection and use of individual diagnostic methods and procedures. Knowledge of the objective state construction after a fire is the basis for determining the procedure of its subsequent remediation.

26.3.2021
Ing. Ondřej Nespěšný, Ing. David Jun, doc. Ing. Jan Pěnčík, Ph.D., Ing. Zuzana Fišarová, Ph.D.

The Helmholtz resonator is one of the most widely used low and medium frequency attenuation acoustic absorbers. While commercial products usually offer efficiency across almost the entire spectrum under consideration, in many cases only the specific natural resonance of the room needs to be suppressed. In such cases, it is necessary to proceed with your own design. This paper presents one of the possibilities of calculating a perforated resonator using the electro-acoustic analogy and the transfer matrix method. This method is not demanding on computing power, but nevertheless it is rarely used in current building-acoustic practice. This paper focuses on the comparison of the calculation of the sound absorption coefficient by this method with the data measured in the reverberation room.

22.3.2021
Ing. Libor Šteffek, Ph.D., Ing. Jiří Kalánek, Ph.D., prof. Ing. Milan Ostrý, Ph.D.

The paper deals with the energy balance of windows for different combination of glazing parameters in connection with their orientation. Sum of solar gains through the transparent surfaces of a building envelope depends mainly on the size, their orientation and the g-value. Large glazed surfaces with correct orientation ensure large solar gains, but they are also the weakest part of the thermal isulating building envelope.
The influences of various U-value (Ug) and g-value of glazing on the energy performance of selected passive house were calculated by the use of computer simulation.

15.3.2021
Ing. Stanislav Bíza, SASTA CZ, a.s.

The subject of the complex repair of the ceiling structure of the water reservoir Pasohlávky was the remediation and static provision of the unsatisfactory reinforced concrete structure. The original condition was inadequate, parts of the concrete structure were dropped due to steel due to steel corrosion and small cover layers of concrete.

15.3.2021
doc. Ing. Jan Kaňka, Ph.D., člen TNK 76 Osvětlení, ČKAIT Praha

The European standard ČSN EN 17037 Daylighting of buildings has been valid in the Czech Republic since August 2019. A year and a half is enough time for the first evaluation of its functioning in project practice. The author of the article deals intensively with this practice and in this paper he would like to share some of his findings concerning the assessment of solar exposure of buildings according to this new European standard. On the edge of this problem, the relationship between accuracy and uniformity in normative requirements is also discussed.

8.3.2021
prof. Ing. Josef Macháček, DrSc., ČVUT v Praze, Fakulta stavební

The article presents a stability analysis of circular arches under various uniform loadings (vertical to the arch plan, vertical to the arch length or radial to the arch axis). Linear bifurcation analysis resulted into critical loadings used for determination of the arches buckling length factors. With the exception of the radial loading the variable axial arch forces need to be taken into account also for the relative Euler basic strut. The analysis covers various boundary conditions of the arches in supports. The study embodies arches with both closed and open cross sections and proved the significant impact of the cross-sectional shape on out-of-plane buckling values. The article outcomes are tables with correct buckling length factors of arches.


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