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Archiv článků od 6.11.2017 do 14.5.2018

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14.5.2018
Ing. Michal Venglár, prof. Ing. Milan Sokol, PhD., Ing. Katarína Lamperová

The article is devoted to extraction of some mode-shapes from measured data during the operational state. The measured bridge is in Bratislava and connects two city districts: The Old Town and the Petrzalka district. The structure is an asymmetric cable-stayed steel bridge with an orthotropic 2-box beam supported in one plane by cables from an inclined pylon. The bridge was measured twice, firstly in 2016 and secondly in 2017. Ambient vibration data were acquired during the measurements. The FEM model has been prepared before the measurements. Some mode-shapes were identified from the data and then compared to the calculated ones.

7.5.2018
doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová

Wood and the materials on its basis fulfil the requirements of an ever-evolving and accelerating society. In addition to naturally grown wood, wood-based materials are frequently used as a basic material for production of furniture and for building constructions as well. Looking at changes in waste management, a significant shift from the waste to the circular economy can be observed. The valuable raw materials are kept in the production cycle instead of landfilling or burning. Wood and wooden products can be efficiently separated in waste management, reused and recycled. The so-called wood waste – old furniture, wooden pallets, window and door frames, demolition wood, used lumber, bark and other wood residues can be reused in particleboard production. Particle board manufacturers in the Czech Republic have adopted progressive waste management and currently use 60% of recycled wood into particle boards. A completed life cycle analysis (LCA) of OSB demonstrates that replacing of 50% of natural fibres with recycled wood has significant environmental benefits. The objective is to push furthermore on effective legislation to promote waste material utilization and thus lead to a more sophisticated waste wood collecting.

23.4.2018
Ing. Lukáš Velebil, Ing. Jan Včelák, Ph.D., Ing. Kristýna Čápová, Ing. Milan Dvořák

The paper deals with the experimental analysis aimed at function verification of fiber optic sensors (Fiber Bragg Gratings). The sensors are used for mechanical stress measurement in wooden load-bearing structures. Glued laminated timber beam with built-in fiber optic sensor system was mechanically loaded during two bending tests. The data obtained using the fiber optic sensors were compared with the results of reference measurement method and analytical calculation.

26.3.2018
Ing. Jaromír Láník, Ph.D., Ing. Tereza Komárková

Diagnostics of building structures are used in non-destructive and destructive methods for evaluation of selected properties of building materials. Structural elements but also selected parts are assessed. Ultrasonic method, which is among the non-destructive testing methods, is being used for the diagnosis of concrete and steel structures for many years. The paper presents possibilities of carrying out inspections of selected elements of steel structures.

26.3.2018
doc. Ing. Radomír Sokolář, Ph.D., VUT FAST Brno, Ústav technologie stavebních hmot a dílců,

Sintering activity (dependence of porosity, flexural strength and firing shrinkage on the firing temperature) of feldspar dust (Casial) which is generated during the milling of potassium feldspar in Halamky quarry was determined. Potassium industrially milled feldspar Z75K13 as a reference material with similar granulometry and mineralogical composition with Casial was used for comparison. More intensive sintering activity showed dry pressed samples based on Casial in comparison with feldspar Z75K13 (about 30 °C lower sintering temperature – 1180 °C). Casial created red body after firing thanks to higher content of Fe2O3.

19.3.2018
Ing. Luděk Vejvara, Ph.D., Západočeská univerzita v Plzni, Katedra mechaniky

The magnitude of the load on the walls of tall wooden constructions can be assembled according to the existing standards according to the valid combination equations in several ways. There are differences between the results. Determining the appropriate procedure for determining vertical strength from construction in different parts of building preparation and comparing it with other options is the subject of this paper.

19.3.2018
Ing. Jakub Hodul, Ing. Jana Hodná, prof. Ing. Rostislav Drochytka, CSc.,

Within this work possibility of using four kinds of waste glass as a replacement for the commonly used filler, silica sand DORSILIT, to epoxy based polymer concrete (PC) is experimentally verified. Determination of compressive and flexural strength, chemical resistance and thermal resistance is examined in order to find out if PC containing waste glass as filler can be used for rehabilitation of concrete structures. Even based on the results of the tests it will be assessed whether it is possible replace DORSILIT by waste glass.

12.3.2018
Ing. Daniel Mátl, Ing. Lenka Nevřivová, Ph.D.

There are applications of refractory concretes for places where these are exposed to corrosive environments. This text deals with both description the corrosive effects and methodology of their testing. One of the most important properties of materials, affecting the chemical corrosion resistance, is their density. The second part of this text is focused on testing the refractory concretes which are currently used for applications. The aggregates were tested for the resistance to sulfuric acid.

5.3.2018
doc. Ing. Michal Stehlík, Ph.D., Ústav stavebního zkušebnictví, Fakulta stavební, Vysoké učení technické v Brně

Adding structural fibres into concrete has an impact, both positive and negative, on the long-term durability of concrete. Polymer fibres do not resist shrinkage of the concrete, steel fibres, on the other hand, create a tough skeleton preventing deformation. Porous structure of fibre concretes exposed for a long time in the environment of CO2 is estimated using the method of determining the coefficient of diffusion resistence and the method of determining the capillary hight. Comparison of measured capillary hight and diffusion coefficient of fibreconcrete samples bring the knowledge, that close correlation between both quantities does not exist, due to the physical difference between determination of both quantities.

26.2.2018
Ing. Martin Križma, PhD., doc. Ing. Ľubomír Bolha, PhD., doc. Ing. Martin Moravčík, PhD., Mgr. Matúš Holúbek, PhD.

With strengthening of damaged concrete linear elements have been engaged since 2003. It is a co – ÚSTARCH SAS Bratislava, FCE University of Zilina, STU Bratislava. Repaired the damaged components – new the coupling plate with reinforced contact, the coupling plate without reinforcement – replacing the geometrical condition of contact. The use of GFRP panels. The effect of the time factor on both the MS.

26.2.2018
Ing. Zuzana Lacová, doc. Ing. Juraj Olbřímek, PhD.

The detail of the chimney system passage is one of the possible details, from a fire point of view, that occurred due to the installation of new chimney systems in to the construction of the building. The chimney system passing through the combustible structure is one of the most dangerous details in the building, from a fire safety point of view, and as practice shows, is often very underestimated. An appropriate solution for the chimney passage requires the knowledge and correct design, as well as the realization and consequently correct use of the thermal appliance and the chimney system. The article deals with passage according to the requirements of the national standards for fire segments and design according to STN EN for chimneys.

19.2.2018
Ing. Ondrej Bajza, doc. Ing. Alena Rohanová

The text describes why and under what conditions the use of beech wood in building structures. Given the legislative and experimental requirements for verification of properties of beech sorting into classes of forts "D". Evaluation of the quality beech wood over the strength of the reliable design, production technology class predictive level as well as the durability of wooden building elements.

© M. Schuppich - Fotolia.com
29.1.2018
Ing. Věra Heřmánková, Ph.D., Ing. Ondřej Anton, Ph.D., Ing. Tereza Komárková

Article deals with finding of physical and mechanical properties of timber at various moisture and it also verifies addictions of single properties on moisture content of timber. In experimental part of this thesis, the density, the dimensional and volumetric swelling and the compressive strength parallel to fibre will be determined on test samples. After evaluating all the tests, the graphs of these parameters depend on various samples of wood moisture determined by weight will be created.

15.1.2018
Ing. Vít Černý, Ph.D., Ing. Ján Fleischhacker, prof. ing. Rostislav Drochytka, CSc., MBA

Tobermorite is the main mineral compound of AAC. It increases its mechanical properties. There needs to be done research of influence of type of silica components on the mineralogical compound of AAC. In the presence study, we examine the usage of nature and artificial silicious materials. Closure of the study will be design of the optimal raw material composition, also hydrothermal treatment of autoclaved aerated concrete.

Stavba stanice metra na Náměstí Republiky
25.12.2017
Ing. Tomáš Moravec, STACHEMA CZ s.r.o.

The article describes the beginnings of the use of the fly ash mixture for the production of concrete in the Czech Republic, its application on important buildings (Prague subway, Nuclear power plant Temelín) and impacts on the production technology.

Složitá rekonstrukce staršího bytového domu
18.12.2017
Ing. Jan Koláček, Ph.D., doc. Ing. Zdeněk Bažant, CSc.

In December of year 2016 has been finished the extensive reconstruction of the multi-family house built in the thirties of last century, located in the district Žabovřesky of the city Brno. Investor with architect desired the modern appearance of interior and facade of the house, which involved a number of difficult renovations and new structures that had to be consulted with structure engineer. The significant steps of the reconstruction of the multi-family house are described in detail in this contribution.

Moderní metody pro měření osových sil v prvcích stavebních konstrukcí
11.12.2017
Ing. Tomáš Klier, prof. Ing. Michal Polák, CSc.

In many practical cases it is important to know the actual value of tensile forces in prestressed elements of civil engineering structures. Main conclusions from experiments which were carried out within verification process and in situ application of the new method for an experimental estimation of the tensile force are described in the paper. The method is suitable for new structures and especially for existing ones.

Analýza trvanlivosti preimyselných komínov © Imperium Obrazu - Fotolia.com
13.11.2017
prof. Ing. Juraj Bilčík, PhD., Ing. Ivan Hollý, PhD., Ing. Natália Gažovičová

Industrial chimneys are civil engineering works, which in addition to static and dynamic effects, direct and indirect loads, are also exposed to significant non-stationary environmental loads. Analysis of their durability focuses on the evaluation of vertical cracks, corrosion of concrete and reinforcement, which have a decisive influence on the resistance of the chimney's shaft with regard to the ultimate and serviceability limit states, as well as their durability.

6.11.2017
Ing. Ján Ježko, PhD., Katedra geodézie, Stavebná fakulta, STU v Bratislave

The article describes the methods of the surveying data and documentation production. The documentation is used for the process of planning, realisation and reconstruction of transport, energetic, industrial, ecologic and public objects. The documentation is also used in the remediation process and the protection of the buildings and historical objects. In these processes, it is necessary to know the spatial dimension – location data, the location of these objects on the Earth's surface and shape and dimensions of these objects. The activities that lead to the realisation, reconstruction and remediation of building objects require a quality maps, photogrammetric images and geodetic models (3D models), which are mostly realised in a suitable interactive graphic PC system in 3D digital form.


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