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Archiv článků od 29.7.2019 do 6.4.2020

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6.4.2020
Ing. Ivan Hollý, PhD., Ing. Iyad , Abrahoim. PhD.

The construction of precast hous consists of prefabricated concrete walls and floor slabs. These elements through joints form rigid spatial (so-called box) load-bearing system. The prefbricated elements of this system were designed for certain layout and static possibilities of the panel system. All additional interventions in the load-bearing structure must be thoroughly investigated. If necessary, it is also necessary to propose a suitable way of strengthening the weakened parts of the load-bearing system.

23.3.2020
Ing. Michal Drahorád, Ph.D., ČVUT Praha, Fakulta stavební, katedra betonových a zděných konstrukcí

This article is focused on current situation in preparation of new generation of European standard for design of concrete structures prEN 1992-1-1. This article deals with main features and development in design principles involved in new standard. In these days there is available the 4th draft of standard for comments of national authorities and experts. The final draft of prEN 1992-1-1 should be finished this year (2020) and provided to formal vote in CEN.

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2.3.2020
doc. Ing. Jana Marková, CSc., ČVUT Praha, Kloknerův ústav

Eurocodes EN 1991 for the basis of structural design and EN 1991 for actions, currently under development in the Technical Committee CEN/TC 250, should be more user-friendly in the 2nd generation of Eurocodes. They will provide basic design procedures, new types of actions and improved theoretical models which will be applied for the design of structures. For effective and economic implementation of 2nd gneration of Eurocodes into the systém of Czech standards, correct decision on National Determined Parameters is needed.

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24.2.2020
prof. Ing. Milan Holický, Ph.D., DrSc., ČVUT Praha, Kloknerův ústav

The article presents the basic criteria in the evaluation of structures of historical buildings. The whole procedure is described in detail in EN 13822, Annex I. The intention is also to provide additional guidance on the application of this International Standard for the construction of cultural heritage buildings. The instructions given here are to be followed in conjunction with all other clauses of the internationally applicable standard EN 13822 and other regulations.

17.2.2020
doc. Ing. Jan Masopust, CSc., ČVUT Praha, Fakulta stavební, katedra geotechniky

The paper deals with the constructions from jet grouting (JG), which is one of the most modern methods of special geotechnical works. JG is the technique of mixing in-situ soil with the energy of high-pressure jet of slurry. The definitions and types of JG are given in the first part: single fluid, double fluid and triple fluid. The second part concerns JG implementation technology and also lists the necessary activities in designing and implementing JG elements and structures. In the third part, examples show the field of use of JG, including deep foundations, for which the example of static load test is given.

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13.1.2020
doc. Ing. Vladimír Tichomirov, CSc., LL.M., Ing. Marek Kervitcer

In this paper, the authors consider the aspects of routine procedure compared to the expert approach in solving construction defects and failures. For better orientation in the issue the basic terminology of defects and failures sphere is given. Also, the authors describe in details the course of both solutions, contemplate their specific aspects and point out their consequences. An essential part of the article is presentation of the potential benefits of the expert approach, the advantages of the expert approach are emphasized in the conclusion.

6.1.2020
Ing. Dagmar Michoinová, Ph.D., Národní památkový ústav ČR, Technologická laboratoř,

The paper discusses the importance of water absorption of traditional building materials and the ability of traditional non-insulated buildings to withstand rising damp. It also draws attention to some of the risks involved in reducing the water absorption of building materials designed for remediation of moisture and salts problems of traditional buildings.

30.12.2019
doc. Ing. Petr Cikrle, Ph.D., Ing. Sabina Hüblová, Ing. Zuzana Oščatková, Mgr. Veronika Singrová

This article describes how to monitor panel house faults. Object movements are measured by a Hollan deformeter (used to measure changes in crack widths and joints) and by floor leveling.

23.12.2019
Ing. Jiří Kunecký, Ph.D., Ing. Martin Hataj, Ph.D., Ing. Hana Hasníková, Ph.D., Ing. Jaromír Milch, Ph.D., Ing. Monika Tyrová, Ing. Pavlína Suchomelová

Oak dowels find its use in carpentry joints, reconstructions of buildings and, also, dowel-joined CLT panels put together without adhesives. The article deals with influence of manufacturing techniques and shape of the cross-section on the bearing capacity of the dowels. Round shape (turning and perforation through steel hole) and hand hawing to the octagonal shape was tested. The results show negligible influence of manufacturing techniques on studied quantity.

16.12.2019
Ing. Lukáš Velebil, doc. Ing. Petr Kuklík, CSc.

The paper presents the results of experimental analysis and an analytical model describing the behavior of racking shear walls made of mechanically joined cross laminated timber. Tests of wall panels, tests for determination of stiffness of layers’ joints and material tests were carried out as part of experimental analysis. Outputs from the layer stiffness tests and material tests are used as input data for the analytical model. The analytical model is based on a component method that considers a wall panel as a system of interconnected elements. The action of the elements is described by springs with defined stiffness. The results of the experiments and the analytical procedure are then compared with each other.

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25.11.2019
Ing. Otto Dvořák, Ph.D., VŠB TUO FBI Ostrava, externí školitel

The article briefly introduces basic technical terminology, errors and computational algorithms for estimating uncertainty of type A, type B, combined and extended uncertainty of test results and that the test management performs the tasks specified in the standard ČSN EN ISO / IEC 17025.

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13.11.2019
Ing. Zuzana Vidholdová, PhD., Ing. Gabriela Slabejová, PhD.

Treatment of wood surfaces with various finish coating materials is recommended for long term protection of wood products exposed outdoor. However, in practice it can happen that wood in constructions has been attacked by wood decay fungi before to application of a finish. In this work, selected properties of sapwood and heartwood of pine (Pinus sylvestris, L.) surface such as surface roughness and adhesion of coating film were investigated on the surfaces attacked by wood decay fungi (Coniophora puteana and Trametes versicolor) and wood staining fungus (Aureobasidium pullulans). Two coating materials useable for wooden constructions in exterior conditions were used: dark brown long-oil alkyd-based system and light brown oil-based surface treatment. The result of the pull-off test for adhesion of both surface treatments was significantly greater on the heartwood surfaces than on the sapwood surfaces of the sound wood. With the increasing time of wood degradation by fungi, the adhesion of the alkyd surface treatment decreased on the sapwood. Adhesion of the oil surface treatment was comparable on the both sound and decayed wood. According to the disruption analysis following the pulling of the dolly, the weakest point was the surface layer of the wood impregnated with coatings. The adhesion of the both surface treatments is comparable to the sound and wood affected with the staining fungus.

7.10.2019
doc. Ing. Pavel Schmid, Ph.D., Ing. Petr Daněk, Ph.D., Ing. Iva Rozsypalová, Ing. Petr Gabriel

The paper deals with a case study of building defects inspection of Lužánky Free Time Centre in Brno. It is described the history of the building and the building diagnostics. There were used the survey methods of visual-defectoscopic inspection, semidestructive diagnosis and diagnosis of foundations and foundation soil. The conclusions contain recommendations for immediate and long-term solution of the object's static problems.

2.10.2019
doc. Ing. Jiří Brožovský, CSc., VUT FAST Brno pracoviště AdMaS

Rebound hammers complying with the specifications of ČSN EN 12504-2 resp. ČSN 73 1373 is used primarily for the determination of compressive strength of concrete in the structure. The paper presents the knowledge of the use of mechanical rebound hammer with impact energy of 0.735 N.m (type L) for the determination of compressive strength and tensile bending of calcium silicate bricks 290 × 140 × 65 mm. Calibration relationships for compression and tensile strength bending from the rebound number are presented. In practice, the calibration relationship for compressive strength prediction is applicable, the relationship for tensile bending strength does not show sufficient tightness between the variables and can only be used provided that a refinement coefficient is defined in the sense of ČSN 73 1370.

7.9.2019
Ing. Lukáš Bříza, VUT Brno

An important part of the construction is the lifting mechanism. If it is used properly and efficiently, the schedule and the completion date of the construction can be better followed. Incorrect or inefficient use of lifting mechanisms leads to unwanted downtime, failure to meet the potential of the mechanism, or overflowing it with a number of ongoing work processes. With the help of data collection (lifting load time), we try to map the use of lifting mechanisms throughout the construction. The obtained and properly evaluated data will serve as a basis for the simulation model to assess the effective use of the lifting device on the site.

2.9.2019
prof. Ing. Leonard Hobst, CSc., doc. Ing. Petr Cikrle, Ph.D.

Steel structures are preferably used to build existing structures. However, when designing them, it is necessary to adhere to precise principles to avoid malfunctions during operation, such as condensation of water, in case of poorly chosen structure of the structure. Some nondestructive testing methods can be used to detect these potential defects.

19.8.2019
doc. Ing. Bohumil Straka, CSc., Ing. Milan Šmak, Ph.D., doc. Ing. Jan Vaněrek, Ph.D.

Survey of the real impact of historical and older constructions and constructions realized in the present period clearly shows that wood and wood-based materials are among efficient and still promising construction materials. The paper is compiled mainly on the basis of the knowledge gained during the verification of the properties of structures, in whose design and implementation the authors participated, and on the evaluation of the results of the survey of structures for the purpose of their remediation or reconstruction.

12.8.2019
Ing. Vítězslav Vacek, CSc., doc. Ing. Jiří Kolísko, Ph.D., Ing. Petr Pokorný, Ph.D.

The prestressing reinforcement has been widely used to reinforce pre-stressed and posttensioned concrete structures. The recent failures of some prestressed bridge structures, caused by corrosion of the prestressing reinforcement, had generated strong interest from engineers in the problem of reinforcement corrosion and its corrosion protection. The paper presents our experience in the diagnostics of corroded prestressed structures in connection with the possibilities restoration of them.

29.7.2019
Ing. Radim Kučera, prof. Ing. Miroslav Novotný, CSc., doc. Ing. Karel Šuhajda, Ph.D., Ing. Martin Pánek, Ing. Tomáš Mecko

A wide range of requirements are laid out for stair construction, which are based on general construction requirements. These are mainly structural fire resistance, static resistance, mechanical resistance, appearance requirements and more. This article focuses on existing material and structural solutions for staircases used in modern wooden constructions and on the possibilities of using cement-fibre boards to build a staircase. The article summarizes the general advantages and disadvantages of this solution and represents the basic design solution.


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