Nejnavštěvovanější odborný web
pro stavebnictví a technická zařízení budov
estav.tvnový videoportál

Stavební fyzika
Archiv článků od 6.7.2015 do 6.3.2017

Archiv recenzovaných článků

zpět na aktuální články

6.3.2017
Ing. Šárka Nenadálová, Ing. Lukáš Balík, Ph.D., Ing. Milan Rydval, Ing. Tomáš Bittner

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.

20.2.2017
doc. Ing. Jan Kaňka, Ph.D., člen TNK 76 Osvětlení, ČKAIT 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.

9.1.2017
Ing. Miroslav Kučera, Ph.D., ČVUT v Praze, Fakulta strojní, Ústav techniky prostředí, Časopis Vytápění, větrání, 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.

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.

25.7.2016
Ing. Jakub Šlik, Ing. et Ing. Richard Hlaváč

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.

11.7.2016
Ing. Jan Šlechta, Ph.D., Stavební fakulta, ČVUT v Praze

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).

21.3.2016
Ing. Bohumil Koželouh, CSc., soudní znalec

Examples 9 to 15. Preface and helping data for calculation see Part 1 to 3.

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.

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

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.

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.

16.11.2015
Ing. Michal Frank, Ing. Martina Drdlová, Ing. Vladan Prachař, Prof. Ing. Jaroslav Buchar, DrSc.

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.

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.

9.11.2015
Ing. arch. Marcela Kubů, Ing. Marcela Bosáčková

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.

2.11.2015
doc. Ing. Zdeněk Bažant, CSc., doc. Ing. Miloš Zich, Ph.D.

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.

2.11.2015
doc. Ing. Jan Kaňka, Ph.D., člen TNK 76 Osvětlení, ČKAIT 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.

19.10.2015
Ing. Martina Drdlová, Ing. Vladan Prachař

Wilful attack targeted on strategic buildings and critical infrastructure can pose significant thread to property and human lives. By modification of the material traditionally used in building industry, in particular by addition of randomly dispersed fibre reinforcement in currently most spread building material – concrete, the enhancement of the blast and ballistic resistance can be effectively achieved without high additional costs. Within the research works presented in this article, the influence of several types of fibre reinforcement on the blast resistance of the concrete panel was assessed. The results of real blast tests indicates, that incorporation of any type of fibre brings enhancement of the blast resistance of the concrete, but the level is highly affected by strength and shape characteristics of the fibre.

12.10.2015
Ing. Peter Buday, PhD., Ing. Rastislav Ingeli, PhD.

The thermal performance of any building component is the result not only of its thermo-physical properties but also of a way of final installation and connections altogether of their all elements. In addition, thermal leakage and bridging in buildings can eventually contribute to a multitude of problems. The thermal bridge is the place in the building envelope through which heat transfer has a multi-dimensional nature. That is why in recent studies, the issue of heat transfer phenomena in the building components has been taken as a multi-dimensional into account more frequently. One of the specific details that create thermal leakage is located in balcony slabs. This paper is focused on advanced analysis of thermal performance of thermal break element applied in balcony slab with parametric correlation to the thermal properties of wall building envelope. Particular cases of commonly used balcony systems in buildings are observed related to multi-dimensional and parametric approach of modeling. Finally a finding of many aspects, such as building geometry, thermal properties variation and structural type importance are observed as certain influence to thermal bridges magnitude and final thermal performance of balcony slab detail.

28.9.2015
Ing. Pavel Rubáš, Ph.D., Technický a zkušební ústav stavební Praha s.p.

The article is a summary of proposals from acoustic experts from European countries participating in COST TU0901 “Harmonizing Sound Insulation Aspects” It includes detailed building acoustic data and their comparisons from the countries involved in the project.

6.7.2015
Ing. Jozef Bednar, PhD., Dr. Martin Teibinger, Dr. Julia Bachinger, Dipl. Ing. Irmgard Matzinger

The present study reveals the influence of typical wind permeability of connections at the eaves on thermal losses. Therefore, a laboratory test and a field test with different insulation materials and different typical geometries of the gap at the eaves were carried out. In order to show the influence on the heat flow rate dependent on insulation material characteristics, three insulations with different densities and air flow resistances were chosen. Furthermore, in the laboratory test the roof inclination, the insulation thickness and the fixation of the roofing underlayment were varied.for the laboratory test, a part of a roof was constructed in the climate chamber. Hence, an influence on the heat flow rate depending on the insulation material has been detected. Where as cellulose insulation and the heavy mineral wool show no significant reaction of the heat flow under different wind velocities and different gap sizes, the investigated lightweight mineral wool insulation shows an important variation of the Uvalue. For the field test, a typically pitched roof was constructed, the eaves placed in the main direction of the wind. It was shown, that the influence of wind on the heat flow rate is negligible if the gaps at the eaves are masked by a projecting roof. The outcome of the research project will lead to a modification of a national construction standard.


zpět na aktuální články
 
 
Reklama