Archiv článků od 15.1.2018 do 18.6.2018

zadejte vlastní článek

zpět na aktuální články       1  2  3  4  5  6  7  8  9  10  ...   

Reconstruction of wooden ceilings – timber joists mechanically jointed with wood-based boards

18.6.2018 | Ing. Zdeněk Vejpustek, Ph.D., doc. Ing. Bohumil Straka, CSc., doc. Ing. Jan Vaněrek, Ph.D., VUT FAST Brno
This paper shows the process of restoration, of a historic wooden ceiling, using a “dry method” – interaction between historic timber joists that are mechanically jointed with wood-based boards.The paper describes reasons for choosing the method and principles of a good design. The experience of using this method on site is also described in this article.
© smereka - Fotolia.com

The Formation of Gaseous Products at Thermal Degradation of the Retardant Treated Fir Wood

18.6.2018 | Ing. Veronika Veľková, PhD., prof. RNDr. Danica Kačíková, PhD., prof. RNDr. František Kačík, PhD., Ing. Tatiana Bubeníková, PhD., Ing. Katarína Trebulová, Drevárska fakulta, Technická univerzita vo Zvolene
The work is focused on the investigation of the formation of gaseous thermal degradation products of retarded firwood. Samples of firwood were impregnated with solutions of 6 inorganic salts, thermally loaded and the arising gaseous products analyzed by SPME-GC-MS. There were 20 compounds identified, the highest amount was achieved for acetic acid and 2-furaldehyde as typical representatives of wood degradation. Most compounds were identified by degradation of samples treated with boric acid solution, at least with ammonium dihydrogenphosphate. The smallest amount of acetic acid and 2-furaldehyde was determined by treating of fir samples with sodium tetraborate solution, which appears to be a very suitable wood treatment agent for fire protection.
© cpauschert - Fotolia.com

Mediation Principle in Urban Planning

4.6.2018 | Bc. Jan Tichý, Vysoké učení technické v Brně, Fakulta stavební
This paper aims to outline basic requirements for the creation of the mediating institution in the urban planning process. It applies the work of the Austrian School of Economics on the urban planning system. It reviews the current state of the system of urban planning, it’s hierarchy. Decision-making process, the role of public, and the role of private investors and developers. To increase the quality of the urban planning process, it establishes the principle of mediation, which aims to change the positions of all sides involved. The core of the mediation principle is to use the unique knowledge and position of the three main sides of the process, being developers, public, and public administration. Establishing of a productive dialogue between all sides can create a more effective urban development.

Long-term physical-mechanical characteristics of aerial-lime based mortars with guar gum derivatives

28.5.2018 | Ing. Tomáš Žižlavský, Vysoké učení technické v Brně, Fakulta stavební, Ústav chemie
This paper studies the possibility of usage of the guar gum and its derivatives as admixtures for aerial lime-based mortars. The influence on the properties of mortars was studied on the aerial lime–based mortars prepared with quartz fine grained sand and doses of admixtures ranging between 0,5 and 10 ‰. The hardened bulk densities, flexural and compressive strength, carbonation rate, workability though flow table test and air content in fresh mortar were studied. The addition of the hydroxypropyl guar (HPG) lowered the bulk density (due to an air intake), improved workability, slightly increased the strength and slowed carbonation rate. The addition of carboxymethylhydroxypropyl guar (CMHPG) does not impact the bulk density and air content in the fresh mortar, the strengths were increased similarly to HPG: it does not impact carbonation rate significantly, so the long term strengths were comparative with the HPG. The pure guaran was found not to be beneficial for the lime mortars.

Environmental benefits of using recycled wood to produce agglomerated materials (Part 3)

21.5.2018 | doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová, Česká zemědělská univerzita v Praze (ČZU), Fakulta lesnická a dřevařská, katedra dřevěných výrobků a konstrukcí
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.

Operational Modal Analysis of the „SNP“ Bridge in Bratislava

14.5.2018 | Ing. Michal Venglár, prof. Ing. Milan Sokol, PhD., Ing. Katarína Lamperová, Slovenská technická univerzita v Bratislave, Stavebná fakulta, Katedra stavebnej mechaniky
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.

Environmental benefits of using recycled wood to produce agglomerated materials (Part 2)

14.5.2018 | doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová, Česká zemědělská univerzita v Praze (ČZU), Fakulta lesnická a dřevařská, katedra dřevěných výrobků a konstrukcí
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.

Environmental benefits of using recycled wood to produce agglomerated materials (Part 1)

7.5.2018 | doc. Ing. Milan Gaff, Ph.D., Ing. Kamil Trgala, Ph.D., Ing. Tereza Adamová, Česká zemědělská univerzita v Praze, Fakulta lesnická a dřevařská
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.

Experimental analysis aimed at function verification of fiber optic sensors

23.4.2018 | Ing. Lukáš Velebil, Ing. Jan Včelák, Ph.D., Ing. Kristýna Čápová, ČVUT v Praze, pracoviště UCEEB, Ing. Milan Dvořák, Safibra Říčany
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.

Ultrasound as a possible tool for inspection of steel structural elements

26.3.2018 | Ing. Jaromír Láník, Ph.D., Ing. Tereza Komárková, Ústav stavebního zkušebnictví, Fakulta stavební, Vysoké učení technické v Brně
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.

Alternative feldspar flux for ceramic technology

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.

Determination of vertical forces from load of a wooden high-rise building

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.

Development of polymer concrete with the content of waste glass usable in the repair of concrete structures

19.3.2018 | Ing. Jakub Hodul, Ing. Jana Hodná, prof. Ing. Rostislav Drochytka, CSc.,, Ústav technologie stavebních hmot a dílců, Fakulta stavební, Vysoké učení technické v Brně, Centrum AdMaS
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.

Resistance of refractories against acidic environment

12.3.2018 | Ing. Daniel Mátl, Ing. Lenka Nevřivová, Ph.D., Ústav technologie stavebních hmot a dílců, Fakulta stavební, Vysoké učení technické v Brně
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.

Change of Diffusion Coefficient and Capillarity of Fibreconcrete with Concrete Recyclate in Aggresive Environment of CO2

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.

Detail of the chimney system passing through the combustible roof and ceiling structure

26.2.2018 | Ing. Zuzana Lacová, doc. Ing. Juraj Olbřímek, PhD., STU Stavebná fakulta, Bratislava, Slovenská republika
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.

Influence of Time Factor on Resistance and Serviceability of the Damaged and Subsequently Strengtened by Concrete Elements of Rugged Section

26.2.2018 | Ing. Martin Križma, PhD., Ústav stavebníctva a arcitektúry (ÚSTARCH SAV) Bratislava, doc. Ing. Ľubomír Bolha, PhD., Slovenska technická univerzita (STU) Bratislava, doc. Ing. Martin Moravčík, PhD., Žilinská univerzita, Stavebná fakulta, katedra stavebných konštrukcií a mostov, Mgr. Matúš Holúbek, PhD., Slovenská akadémia vied, Ústav stavebníctva a architektúry SAV Bratislava
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.

Beech wood for building structures assessment

19.2.2018 | Ing. Ondrej Bajza, doc. Ing. Alena Rohanová, Katedra drevených stavieb, Drevárska fakulta, Technická univerzita vo Zvolene
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

Physical and Mechanical Properties of Timber at Various Moisture

29.1.2018 | Ing. Věra Heřmánková, Ph.D., Ing. Ondřej Anton, Ph.D., Ing. Tereza Komárková, VUT Brno, Fakulta stavební, Ústav stavebního zkušebnictví
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.

Study of tobermorite formation in dependence on use of various siliceous compontents

15.1.2018 | Ing. Vít Černý, Ph.D., Ing. Ján Fleischhacker, prof. ing. Rostislav Drochytka, CSc., MBA, VUT FAST Brno
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.
zpět na aktuální články       1  2  3  4  5  6  7  8  9  10  ...   
 
 

Aktuální články na ESTAV.czNáchod koupí od JTH za 46 milionů pozemky po bývalé TepněSolární energie pro rodinný dům: Elektrárna pro nezávislý provoz celého domuVybíráte tepelné čerpadlo? Jak srovnat nabídky a správně se rozhodnout?Další vousatý dům stojí v Českých Budějovicích