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Archiv článků od 12.8.2019 do 23.12.2019

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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.

4.12.2019
Josef Krupka, Zakládající člen České hydroizolační společnosti (ČHIS)

The flat roofs of warehouse and production halls show some typical defects. A very common cause of roof problems is incorrect implementation of anchoring detail of the attic. The causes and solutions to these typical defects are described below.

3.12.2019
Miroslava Ševčíková, Vědecko-výzkumný uhelný ústav (VVUÚ) Ostrava Radvanice

In this article, we focus on fundamental element of primary protection – detection devices for registering the rise of hazardous concentrations of gases and vapors. We have chosen and described for each type of device and kind of detected gas basic tests that are necessary for ensuring their correct and reliable function.

Ilustrační obrázek © Dmitry Vereshchagin - Fotolia.com
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.

11.11.2019
prof. Ing. Martin Jiránek, CSc., ČVUT v Praze, Fakulta stavební

The article describes all significant changes in the field of designing and implementing radon protective and remedial measures introduced by the revised version of ČSN 73 0601, which came into force on 1.10.2019. A new way of selecting measures according to the building type and new concept of designing according to the design values of input parameters are introduced. A new methodology for designing radon-proof insulations is described in detail. According to this methodology, only insulation with a radon resistance greater than the prescribed minimum radon resistance can be used for building protection.

Parametrická štúdia tepelnej bilancie budovy, ilustrační snímek © Büros - Fotolia.com
22.10.2019
prof. Ing. Ivan Chmúrny, PhD., Stavebná fakulta STU Bratislava, Katedra konštrukcií pozemných stavieb

Increasing the thermal insulation properties of walls, roofs, floors and windows has a positive effect on reducing heat loss and energy need for heating. However, when assessing the energy need for cooling in buildings with conditioned indoor environment, this tendency to increase the thermal insulation capability may lead to an increase the energy need for cooling, when measures to reduce heat gains by transparent structures are not applied.

14.10.2019
Prof. Ing. Pavol Ďurica, CSc., Ing. Peter Barňák

In the contribution, we are focused on the quality of the heat-moisture microclimate and the aspects that affect it. We chose one office room in the building of the Research Center of the University of Žilina (UNIZA), oriented to the west. The subject of the measurements were all physical components of the indoor environment, the effect of solar radiation through window constructions and floor temperatures using low-temperature radiant floor heating. The contribution describes measuring methods, results of measurements and related partial conclusions for cold climatic conditions of the year.

7.10.2019
Ing. Dana Bellušová, Technický a skúšobný ústav stavebný, n.o.

The contribution deals with the experiment verifying the load bearing capacity of anchors for ETICS with thermal insulation of higher thicknesses. In connection with the increase of the requirements for the energy performance of buildings, the thermal insulation thicknesses are increased to meet the design conditions.

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.

9.9.2019
Ing. Gabriela Slabejová, PhD., Ing. Zuzana Vidholdová, PhD.

Treatment of wood surfaces with various finish coating materials is recommended for long term protection of wood products exposed outdoor. Due to natural weathering, the colour and the surface roughness of uncoated wood is changed. However, in practice it can happen that wood in constructions has been weathered 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 of previous naturally weathered wood Two coating materials useable for wooden constructions in exterior conditions were used: dark brown polyurethane-based system and light brown oil-based surface treatment. The results of pull-off test for adhesion showed that the polyurethane coating film showed the weakest point in the pre-weathered layer of wood substrate and also at the wood/coating interface. The oil-based surface treatment had the weakest place inside the coating film or in the coating penetration layer in the wood substrate. Pre-weathering did not significantly affect the adhesion the coating film on wood. 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.

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.

29.8.2019
Ing. Zdenko Malík, Ing. Kristina Fořtová, Ph.D., Ing. Kamil Staněk, Ph.D., Ing. Jakub Diviš, Ing. Martin Hataj, Ing. Robert Jára, Ph.D., doc. Ing. Petr Kuklík, CSc.

Nowadays, when the demands on the thermal insulation envelope of buildings are increasing, the importance of thermal bridges on the overall thermal loss of the envelope increases. Point thermal bridges are often neglected in the calculations but can lead to an increase in heat loss by an envelope of up to 35%. Significant point thermal bridges are, among other things, elements which ensure anchoring of structures protruding in front of the façade fulfilling the supporting function, since the main emphasis is placed on the bearing capacity of such an element. Several variants of anchoring systems with thermal bridges are available on the market. This paper deals with the thermal-technical assessment of the selected anchoring system and its experimental verification during loading in the climatic chamber.

26.8.2019
Ing. Martin Hataj, Ing. Robert Jára, Ph.D., Ing. Kristina Fořtová, Ph.D., doc. Ing. Petr Kuklík, CSc.

The application of external wall insulation systems is frequent today due to the increasing demand for energy saving in buildings. The structures attached in front of the facade fulfilling the supporting function must be sufficiently anchored to the external load-bearing structures. The thermal bridges solution in the anchoring system is an important factor beyond the bearing capacity. Several variants of anchor systems are available on the market to deal with thermal bridges. This article introduces the currently available solutions and presents experimental results of the selected anchoring system.

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.


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