Archiv článků od 2.11.2015 do 22.5.2017

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Thermal-technical evaluation of inner wall cavities within framework of a suggestion of wet masonry rehabilitation

22.5.2017 | doc. Ing. Jaroslav Solař, Ph.D., VŠB TU Ostrava
For excessive wet masonry rehabilitation, except for other methods, the method of air cavities is used. These can be wall or floor cavities. The wall cavities may be situated either on the internal or the external side of the wall. From the height point of view, internal side cavities can be located under the floor or above the floor level. This contribution only deals with the cavities above the floor level. In the projection practice, the air cavities usually are designed only empirically. But it is necessary to carry out their thermal-technical evaluation for their correct capacity. The matter of the evaluation is the topic of the following contribution.

Energy performance of industrial buildings – PART 1 – LEGISLATION

10.4.2017 | Ing. Jiří Cihlář, CEVRE Consultants s.r.o.
Energy efficiency of industrial buildings in not very common topic. However, the quality of design must be based on valid national legislation and technical standards. Task to achieve best energy ratings is more and more frequently laid on building designer and energy specialist directly from investor – developer.

The invention, patent or utility model - who should sort?

8.3.2017 | Ing. Zdeněk Lyčka
The article explains the differences between the invention patents and utility model from the perspective of Czech legislation. Also highlights the confusion individual categories and purposeful fraud by producers and sellers of equipment.
1 comment, 08.03.2017 07:44

Diffusion Properties of Surface Rehabilitation Mortars

6.3.2017 | Ing. Šárka Nenadálová, Ing. Lukáš Balík, Ph.D., Ing. Milan Rydval, Ing. Tomáš Bittner, Kloknerův ústav ČVUT v Praze
Water vapour permeability is one of significant material properties. The value of water vapour resistance factor is necessary to know to be able to rehabilitate structures, mainly after floods. One thing is essential – to know what are the values of water vapour resistance factor of the used material to know how long the structure will take to be dried and users can come back to live there.

Sound attenuation of a wall with finite length

20.2.2017 | doc. Ing. Jan Kaňka, Ph.D., Stavební fakulta ČVUT Praha
This article continues the discussion [4] from 2010. The wave theory light and of its diffraction was substantiated by French physicist Augustin-Jean Fresnel (l788–1827). Soon we will recall the bicentennial of his discovery. In 1819 Fresnel received Prize of the French Academy of Sciences for discussion of wave diffraction. Wave attenuation is caused by interference. Laws of wave diffraction also apply to the sound. According to them two-dimensional problem i.e. the sound attenuation of a wall with finite length can be solved.

Reducing of Noise from Sources of Heat and Propagation of Sound

9.1.2017 | Ing. Miroslav Kučera, Ph.D., ČVUT v Praze, Fakulta strojní, Ústav techniky prostředí, Časopis Větrání vytápění instalace
The paper presents an example of solving the propagation of noise from an air/water heat pump installed in the basement of an apartment building. Air intake and exhaust are brought out on the façade of the building, where it is calculated the noise situation in the protected exterior of the building. In the interior it is solved the propagation of sound from the plant room to the protected interior space. In conclusion, the results are compared with the data from the report on measurement at the realized work.

The Effect of Local Thermal Bridges on Thermal Performance of Curtain Walling

12.12.2016 | Ing. Roman Jirák, Ph.D., Ing. Petr Jaroš, Ph.D., DECOEN znalecký ústav s.r.o.
U-value calculation of curtain walling is one from more difficult calculation in the civil engineering. In according to trend of increasing glassing surface of building envelope, the curtain walling has big influence on thermal behaver of buildings. This is why it is necessary to calculate the thermal insulation properties with special attention. This article focuses on influence of different local thermal bridges on curtain walling U-value.

Commentary to revision of the government regulation on health protection against negative effects of noise and vibrations

12.9.2016 | Ing. Pavel Rubáš, Ph.D., Technický a zkušební ústav stavební Praha, s. p.
The values of equivalent sound pressure level and maximum sound pressure level are used in the government regulation on health protection against negative effects of noise and vibration as criteria for expressing noise limits. These limits are applied with regard to negative effects of noise in-situ and workplaces The Czech government approved on 15. 6. 2016 the revision of Decree no. 272/2011 Coll. This amendment includes relevant changes of the on the public health protection law that is valid from 1. 12. 2015.

Water vapor permeability of wood according to the density of the material

25.7.2016 | Ing. Jakub Šlik, Ing. et Ing. Richard Hlaváč, ČVUT v Praze, Fakulta stavební, Katedra konstrukcí pozemních staveb
This thesis deals with the water vapor permeability of wood for the most commonly used types of wood for construction work - Norway spruce (Picea Abies). Diffusion of water vapor is solved according to the density of the material, which varies depending on climatic conditions tree growth. These different conditions are in the Czech Republic mainly characterized by different altitude growing zones. Water vapor permeability is solved in the thesis by a method of measuring the diffusion resistance of materials. Specifically, the method of wet cup and dry cup, which is carried out using EN ISO 12572 knowledge and advices of previous researchers of that method. The results were compared with values reported in the Czech standard and later used for construction project of the typical timbered buildings with respect to contemporary legislation.
1 comment, 25.07.2016 07:31

Extended Sharp’s Method for the Calculation of the Airborne Sound Insulation of Building Structures

11.7.2016 | Ing. Jan Šlechta, Ph.D., ČVUT v Praze, Univerzitní centrum energeticky efektivních budov (UCEEB)
The airborne sound insulation of building structures is a subject of permanent interest of designing engineers and architects. Although the weighted apparent sound reduction index is in the final phase verified by measurements in already established buildings, semi-empirical methods have a potential of non-negligible financial savings in the building design phase. The paper presents a set of equations convenient for the calculation of the airborne sound insulation of single and double building structures which extends the Sharp’s method. The equations are derived by mathematical procedures but the purpose of this paper is to supply the reader with a prepared computational tool and that’s why the derivation is listed in different publications. The set of equations is compared with laboratory measurements and other methods both for single (EN 12354-1, Davy’s and Watters’ method) and double structures (Davy’s and Watters’ method).

Eurocode 5 – Design examples

21.3.2016 | Ing. Bohumil Koželouh, CSc., soudní znalec
Examples 9 to 15. Preface and helping data for calculation see Part 1 to 3.

Eurocode 5 – Design examples

14.3.2016 | Ing. Bohumil Koželouh, CSc., soudní znalec
Calculation according to Eurocode 5 examples 1 to 8. Preface and helping data for calculation see Part 1 to 3.

Eurocode 5 – Design examples

29.2.2016 | Ing. Bohumil Koželouh, CSc., soudní znalec
Preface – Helping data (finish): Laterally loaded nails – Values of Johansen strength for prebored and unprebored roud nails – Effective number of fasteners – Values of Johansen strength for dowels/bolts in timber-metal plate joints – Nailed joints strength in tension

Eurocode 5 – Design examples

8.2.2016 | Ing. Bohumil Koželouh, CSc., soudní znalec
Preface – Helping data (continuation): Compression design strength at an angle to the grain – Columns: buckling coefficients for solid timber and for homogeneous glued laminated timber – Stability of members: Beams subjected to bending without compression force – Tilting factors – Laterally loaded joints with dowel type fasteners.

Eurocode 5 – Design examples

1.2.2016 | Ing. Bohumil Koželouh, CSc., soudní znalec
Preface – Helping data (first part): Reference design strengths for solid timber and for homogeneous glued laminated timber – Examples.

Effect on filler to mechanical and dynamic properties of impact energy absorbing materials

16.11.2015 | Ing. Michal Frank, Ing. Martina Drdlová, Ing. Vladan Prachař, VUSTAH Brno, Prof. Ing. Jaroslav Buchar, DrSc., SVS FEM Brno
Research, development and testing of materials and safety features used to protect civilians and armed forces against terrorist or military attacks are more than desirable nowadays. Therefore, our work is aimed at absorption materials that can temper impact energy and shockwave energy originating in explosive blast.
Out of many materials potentially suitable for experiments, two groups of fillers were chosen – macro fillers and micro fillers – and a two component polyurethane binder. In this article, the resulting physico-mechanical characteristics are summarized: bulk density, flexural, compression and impact strength. The crucial test for determination impact energy absorption was the Split-Hopkinson pressure bar test, conducted with most samples.

Preservation of a catacombs of a State castle Lednice. Constructional and technical research is an important step of a preproject preparation

15.11.2015 | Zdeněk Štefek, Pavel Zejda, SAREP a.s.
The basement of a castle greenhouse, so called catacombs, and a terrace with air shafts above them are located to the east by the Palm greenhouse of a state castle Lednice and they are connected with it. Catacombs used to serve as depositaries for storing plants from castle park in a period of winter month. Preservation of greenhouse’s catacombs began in 2004 and was carried out in phases till the end of 2007 when the work was interrupted. In 2012 the investor decided to proceed to finish the second part of a planned reconstruction connected with a reconstruction of basements under the greenhouse terrace. The vital part under the project documentation is also dealing with a rehabilitation of damp masonry including necessary constructional and technical research with respect to dampness and its elimination.

The acoustic properties of external thermal insulation composite systems

9.11.2015 | Ing. arch. Marcela Kubů, Asociace výrobců minerální izolace, Ing. Marcela Bosáčková, Asociace akustiky
Revision of ETAG 004 brought a change in the assessment of noise protection external thermal insulation composite systems (ETICS). Under this revision ETICS may have positive or negative influence on airborne sound insulation of wall on which was applied. The article deals with calculation method of airborne sound insulation, including concrete calculations, and measurements on ETICS with mineral wool.

Failures of expansion joints of building structures

2.11.2015 | doc. Ing. Zdeněk Bažant, CSc., doc. Ing. Miloš Zich, Ph.D., Ústav betonových a zděných konstrukcí, VUT FAST v Brně
Buildings which are issued to natural changes of atmospheric temperature, should be divided to parts that can act independently. If not, the structure itself will be split up according to the general laws of physics and the internal and external form and material properties of the structure. The article describes failures of expansion joints of constructions.

Insolation of buildings in Europe, in the Czech Republic and in Prague

2.11.2015 | doc. Ing. Jan Kaňka, Ph.D., Stavební fakulta ČVUT Praha
The article gives information on the requirements of sunlight in buildings in the European Union and gives a brief historical overview of the normalization of sunlight in our country. On the concrete realization of the residential complex built around 2000 in a closed blocks line is demonstrated the satisfactory insolation in these conditions. From this perspective provides a comment on current events about the preparations of Prague building regulations.
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