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Archiv článků od 23.2.2015 do 17.8.2015

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17.8.2015
Ing. Pavel Rubáš, Ph.D., Ing. Jaroslav Sytař

The article deals with concrete production and its control as interrelated issues, describing in detail the various types of inspections of concrete plants, as well as ČSN EN 206-1, the standard relevant for concrete. Explained here are the mandatory inspections for road construction supplies according to TKP 18, which contains stricter requirements for the equipment and operation of concrete plants, concrete composition, and for control and testing. The process of the initial inspection by a compiled questionnaire is described, where the individual specific essential requirements and the documents issued during inspections are arranged in logical subject units.

10.8.2015
Ivana Nohová, 2. viceprezidentka PKPO

The effort is most builders to get the cheapest project documentation and stamp for start of construction. Little attention has been paid to its proper location. Construction practice is to sit as close to the fence with a neighbor to remain more space for the garden. It should be noted that, under the refers to the construction of any building works that arise construction or assembly technology, regardless of their technical construction design, used in building products, materials and construction, the purpose and duration of use. Under construction is also considered to be a product performing the function of the building. It does not matter if the building is connected to the ground as often by professionals and lay people hear.

27.7.2015
Ing. Václav Ráček, doc. Ing. Jan Vodička, CSc., doc. Ing. Jiří Krátký, CSc.

Utilization of steel fibre reinforced concrete (SFRC) during the design of load-bearing structures presupposes that manufactured SFRC will be classified into the strength classes. For static design, these stated strength in the strength class are necessary: compression, tension when the macrocracks open and agreed limit deflection during the bending test on beams. The paper shows the procedure of determining the strength class of SFRC under such prescriptions. Different arrangement of the test equipment, differences in the ranges of test beams and their modifications affects the procedure for evaluation of tensile strength, including those resulting strength classes. Compressive strength of SFRC is considered in accordance with the evaluation of common (normal) concrete (cylinder/cube). These strength classes, calculated by two methodologies, show the difference in classification of one type of SFRC, in this case by increasing strength of SFRC after formation of the macrocrack caused by higher concentrate of fibres.

29.6.2015
Ing. Pavel Fridrich, Ústav pozemního stavitelství, VUT v Brně

The increased moisture of the building materials causes the change of its mechanical and physical characteristic. In particular the high amount of loose water in construction is harmful to human beings, increase the economic expenses of usage of the building and shorten the lifetime of the building. One of the direct techniques to restore damp proofing and to increase the utility value of the building that have undergone rapid progress in last few years is the injection procedure.With use of experimental methods in my work I deal with evaluation of two injection compounds used in Czech Republic and with its impact on the mechanical characteristics of the mortar.

22.6.2015
Ing. Andrea Nasswettrová, Ph.D., Ing. Pavel Šmíra, Ph.D., Ing. et Ing. Soňa Křivánková

The paper presents the Acoustic Pack device which can record sound emitted by wood-destroying insect larvae while eating wood mass. It records the sound with up to eight sensors at once in several-hour records using high quality acoustic signal recording system. While detecting, it is also possible to hear an activity on a certain element in the structure. This makes it possible to obtain a complete view of the condition of elements with a graphic output of the activity and sound records. Thanks to these advantages, the acoustic system has become a great helper in the detection of damage and in the status analysis of attacked elements in the structure.

15.6.2015
Ing. Aleš Vodička, Ing. Pavel Mlejnek, Ph.D, Ing. Jan Včelák, Ph.D., Ing. Petr Ptáček, Ph.D., doc. Ing. Petr Kuklík, CSc.

The article describes one of the key factors affecting the lifetime of a wooden building – moisture. It shows the most common causes and effects of increased moisture inside a wooden construction. Methods of determining moisture level in it are listed and particular one suitable for continual monitoring is presented. The suitable method is measuring of the resistance and conversion to a moisture level. Corrections of the moisture level for temperature effects and wood type are included.

15.6.2015
Ing. arch. Simona Švecová, doc. Ing. arch. Ivan Vorel, CSc.

The Czech landscape is predominantly a cultural landscape changed for the centuries. It is the cultural heritage connected with the landscape framework – with the terrain relief, water areas, rivers and vegetation. The absence of restriction of the building activities and changes in the use of the territory might cause decline of the historical cultural landscape values and disruption of the landscape cultural identity. The formulation of the cultural landscape value and the method of treatment with it are embodied in the European Convention on the Landscape, in the Preservation of Monuments Act and in the tools of territorial planning. It particularly concerns the designation of the landscape parts as the landscape monument zones, which brings possibilities of the concentrated cultural values protection. It also brings valuable information on the principles of protection for designers and investors. The preservation of the landscape values is embodied in the territorial planning tools. It concerns the principles of territorial development, where the goal characteristics of the landscape are defined; further it concerns the territorial analytic documents of municipalities and a conception of the landscape arrangement in the territorial plans.

18.5.2015
Ing. Václav Ráček, doc. Ing. Jan Vodička, CSc.

The paper presents the basic characteristics of fiber reinforced concrete (FRC) that affect its durability and allow to increase service design life of load bearing construction from FRC. This effect is in more detail demonstrated on the test results of the test samples, i.e. strength characteristics, obtained homogeneity and carbonation. The paper focuses on the SFRC, i.e. FRC when using metallic fibres.

4.5.2015
Ing. Pavel Šmíra, Ph.D., Ing. Andrea Nasswettrová, Ph.D., Ing. et Ing. Soňa Křivánková

The article presents a technological procedure and possibilities for surface treatment of different materials by using compact parts of CO2dry ice. A purifying medium is accelerated in the nozzle of the SDI Select 60 device by compressed air stream to a supersonic speed, and so it reaches high kinetic energy. The impact of CO2 at the temperature −78.8 °C rapidly cools down the surface; dirtiness becomes brittle and loses its base adhesion, causing temperature shock. Simultaneously with this temperature effect, dry ice intensively sublimates, increases its volume and removes, at high inner tension, the impaired surface of dirtiness without any formation of abrasion waste. The device is applicable to the removal of contamination from elements which cannot be saturated with water or when it is necessary to modify elements with no need to dismantle them. The report introduces the technology when removing contamination on the surface of wooden construction elements, artefacts and stone statues, as well as when forming a relief on the native wooden surface and at a surface treatment before the application of paint, or fungicidal and insecticidal agents.

27.4.2015
Ing. Jindřich Sobotka, prof. Ing. Miloslav Novotný, CSc., Ing. Karel Šuhajda, Ph.D., Mgr. Zdeněk Jiroušek

Drying masonry building structures using high-frequency electromagnetic (EMW) radiation, so-called. Microwave technology in construction practice becoming more exercise. It is an innovative method which can be used to remove excess moisture significantly speed. This article focuses on the description of physical phenomena that occur during drying and comparison standard, the most commonly used, processes for drying buildings.

27.4.2015
Ing. Orsolya Katona, Katedra kovových a drevených konštrukcií, Stavebná fakulta, Slovenská technická univerzita v Bratislave

In the last few years the engineered building product cross laminated timber (CLT) has become very common in timber engineering applications. CLT is a cost-competitive wood-based solution that complements the existing light and heavy-frame options, and is a suitable substitute for some applications which currently use concrete, masonry and steel. This contribution deals with the analysis and design of CLT, used as floor elements. Different calculation procedures for plates loaded out-of-plane are discussed. Comprehensive 3D finite element models (ANSYS 14.0), which can be used to analyze the mechanical behaviour of the board of CLT, were developed.

20.4.2015
Ing.arch. et. Ing. Kateřina Štréblová Hronovská, doc. ThLic. Ing. arch. Jiří Kupka, Ph.D.

The landscape character protection is nowadays widely used term within the nature and countryside protection processes that influences the architectonic and urban forms of many construction intentions. It represents some limitations for large construction intentions and also for the single building constructions. It is applied on the landscape protected territories and also on the already settled areas or directly in towns. This article presents different cases when the knowledge of this landscape and nature protection instrument is very important for the architect and shows us the examples when the knowledge can anticipate some unpleasant surprises during the approval process of different construction intentions.

20.4.2015
Ing. Zdeněk Vejpustek, Ph.D., doc. Ing. Bohumil Straka, CSc.

The paper presents the design and construction of the wooden roof structure covering the Penny market building, which is located in the Czech Republic and was built in the summer of 2013. The building of the roof structure was based on the 26 m long elements consisting of 2 or 3 trusses assembled with punched metal plate fasteners and bracing members. The design philosophy, details and descriptions of choosen methods used in the roof design are part of the paper.

13.4.2015
Ing. Martin Sedlmajer, Ph.D., Ing. Adam Hubáček, Ph.D., prof. RNDr. Pavla Rovnaníková, CSc.

The article deals with the properties of concrete with two natural zeolites as a the supplementary cementitious material. The determined parameters bring the findings of basic mechanical propeties and frost resistance of aerated concretes with zeolites. The results of properties of concrete with two different kind of zeolite are compared to reference concrete without zeolite. Concrete with zeolite Z2 showed worse properties due to finer particles.

6.4.2015
Ing. Linda Veselá, Fakulta stavební ČVUT v Praze, Katedra technologie staveb, Útvar technologií a materiálů

Stairs are part of construction. It is important to solve geometrical tolerances of stairs as of other parts of constructions. The most important tolerances of stairs which should be measured are steps (their high and width), because their dimensions could affect safety of stairs.

23.3.2015
Ing. Jan Šlechta, Ing. Jaroslav Vychytil, Ph.D.

The paper summarizes important information related to the field of design of wooden buildings from the point of view of the sound reduction index. The text is focused on wooden structures (both massive wood systems and wood frame systems) as well as on particularities of an acoustic behaviour of wooden floor structures with fillings. General principles are described which may serve as useful hints for architects and project engineers when designing structures with wooden elements. Emphasis is primarily put on the specific acoustic behaviour of wooden buildings in comparison with masonry and concrete structures.

16.3.2015
Ing. Pavel Mlejnek, Ph.D., Ing. Aleš Vodička, Ing. Jan Včelák, Ph.D.

The article describes sensor system for increased moisture detection in construction materials, especially in the wood. The assumption is that a sensor network is built-in into the construction elements of the building and it is connected to a central unit. The goal is to develop a sensor suitable for permanent installation in the construction during realization of the building. The sensor network enables early warning and fast detection of increasing moisture in the building and alert building owner or operator. The sensors will be placed at critical building’s locations with high risk of plumbing accidents. Using the installed sensor system it is possible approximately locate the place of failure, shorten detection time and substantially reduce damage and reconstruction costs.

16.3.2015
Ing. Jiří Nováček, Ph.D., Ing. Jaroslav Vychytil, Ph.D., Ing. Jan Šlechta, Ing. Jaroslav Hejl

The main purpose of this paper is to show how the different structural details affect the airborne sound insulation of lightweight building elements. The sound reduction index of such structures depends on several phenomena like the cavity attenuation, the mass-air-mass resonance, standing waves resonance, sound transmission via sound bridges etc. This paper describes their effect on sound insulation and gives the initiative information for optimized acoustic design.

9.3.2015
Ing. Petr Sejkot, doc. Ing. Petr Kuklík, CSc.

There is a significant possibility of improving the load bearing capacities calculated according to the existing Standards of spatial connections with thin walled metal nailing plates. The reason is that the design of these connecting elements has inadequate support in the existing Standards and Technical Reports. The improvement can make them more consistent with the results from tests. Therefore, research has been called to improve this state of the art. The paper presents the whole experimental study of angle brackets which consists of full-scale experiments, numerical models of the connections, current analytical calculation approaches and proposals how to improve them.

23.2.2015
Ing. Ivana Chromková, VUSTAH Brno

A test of frost resistance of a building material belongs to standard methods of an evaluation of its durability, it expresses a resistance of a building material to a substantial change of temperature and an influence of atmospheric effects regarding to its functionality and utilization in a long-term horizon. The test of frost resistance is time demanding as well as it lays demands on a test equipment of a testing laboratory. This paper describes results of a project, which evaluated a possibility of using a quick indicative test enabling a quick evaluation of a tested concrete regarding its frost resistance. The used indicative test is derived from the standard ČSN 73 73 25 Determination of frost resistance by shorten tests, which has been cancelled without refundation. This method could be beneficial for a quick evaluation of a new designed concrete mixture non-proven in a laboratory. This paper was elaborated with the institutional support for long-term development of research organizations by the Ministry of Industry and Trade of the Czech Republic.


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