Archiv článků od 29.2.2016 do 15.5.2017

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Analytical model for determination of traditional timber butt joints

15.5.2017 | Ing. Martin Hataj, ČVUT v Praze, UCEEB, doc. Ing. Petr Kuklík, CSc., Stavební fakulta, ČVUT v Praze
Computing models for structural behaviour and determination of traditional timber butt joints using analytical relations are presented in this paper. A component method is a base of the computing technique introduced herein. This method is usually used for steel joints design. The component method is based on dividing a joint into individual components. These are defined by partial joint component stiffness. An analytical solution includes a subsidence effect of wooden material in a close proximity of compressive loading. Analytical computation results are compared with the experimental outputs. A design procedure according to Eurocode 5 for a load capacity determination of perpendicularly loaded structural element is stated in the paper.
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Pore size distribution by mercury intrusion porosimetry

8.5.2017 | Ing. Martin Keppert, Ph.D., Univerzitní centrum energeticky efektivních budov (UCEEB) při ČVUT v Praze
The papers aims to illustrate possibility to characterize pore system of wood and to quantify its pore size distribution by mercury intrusion porosimetry as simple and fast experimental method.

Numerical modeling of membrane action of timber-fibre concrete construction in fire

10.4.2017 | Ing. Eva Šopíková, Ph.D., Ing. Petr Vymlátil, Ph.D., Designtec s.r.o., Brno, prof. Ing. František Wald, CSc., Ing. Anna Kuklíková, Ph.D., ČVUT v Praze, Fakulta stavební
This report presents a new method for designing composite timber steel-fibre-reinforced concrete slabs with unprotected secondary timber beams subject to fire, taking tensile membrane action into account. The FE-model consists of material tests, push-out shear tests and beam tests, which had formed a preliminary study. The FE-model represents the behaviour of the floor slab tested in experiment, together with a collapse prediction for the slab. The FE-model with characteristic material properties includes a safety concept based on the Eurocode standards, and is applied to define the fire resistance of various types of timber steel fibre-reinforced concrete flooring.

Microwave theory in construction practice

3.4.2017 | Ing. Jindřich Sobotka, Ph.D., doc. Ing. Karel Šuhajda, Ph.D., VUT Brno, Fakulta stavební, Ústav pozemního stavitelství, Mgr. Zdeněk Jiroušek, S.P.UNI, s.r.o
This paper discusses the practical use of microwave technology in construction practice. Opinions on the use of EMW devices are not only among the general public quite different. From boundless praise, to the uncritical condemnation. The reason for this situation is the lack of awareness of experts and the public about what is and what is not possible to expect from this technology.The article conclusions which we reached on the basis of experiments conducted at the Faculty of Civil Engineering Brno and subsequently verified measurements in field practice. The aim is to provide basic information about how to use microwave technology. Their benefits but also the risks that this technology brings along.
1 comment, 04.04.2017 15:22

Hot-air Treatment of Rožnov Town Office in the Wallachian Open Air Museum in Rožnov pod Radhoštěm

20.3.2017 | Ing. Hynek Kundera, Ing. Andrea Nasswettrová MBA, Ph.D., Ing. Olga Grossová, Ing. Pavel Šmíra MBA, Ph.D., společnost Thermo Sanace s.r.o., Vědeckotechnický park profesora Lista, Brno
The article deals with hot-air treatment of a historically valuable Rožnov town office, built in 1770, which was transported to the Wallachian Open Air Museum in Rožnov pod Radhoštěm in 1924 as the first building of the currently extensive premises of this national cultural heritage. The method of wooden structure hot-air treatment was used for the first time in the territory of the Czech Republic in 2010. It has been used in western European countries (especially Denmark and Germany) approximately since 1930. This comprehensive method is governed by the German standard DIN 68 800 – Part 4 [1] and it is especially used for historically valuable buildings where emphasis is put on the preservation of the original wooden structure attacked by wood-destroying insects, usually of the long-horn beetle family (Cerambycidae) oranobium beetle family (Anobiidae). The goal of the article is to explain the hot-air treatment method to professional public using an example of one of implementations.

Timber beam reinforced by steel cable

27.2.2017 | Ing. Martin Hataj, ČVUT Praha, UCEEB
This paper presents a technical solution for bended timber beams and their strengthening. Beams exposed to bending are of the most common use as structural elements. King-post trusses, sling-braced trusses, tie-rod trusses or additional timber beams were assembled to cover large spans in the past. These structures required using additional structural members which limited the space above or underneath a subjected beam. The technical solution presented herein considers a tie-rod truss principle applied on a beam, similar to post-tensioning reinforced concrete structures.

Crushed Straw Used as a Building Material

20.2.2017 | Ing. Jiří Teslík, Ing. Petr Kurečka, Ing. Naďa Zdražilová, VŠB Technická univerzita Ostrava, Fakulta stavební
Natural building materials are in recent years used still more often in civil engineering. One of these materials is also the straw. By its crushing and cutting into small pieces it is formed so-called crushed straw. The properties of this material, which are important for civil engineering, were not published yet unlike the properties of the straw in bales. In the Czech Republic there exist a many objects built from straw bales. In this paper there are described partial results of research which is implemented on Faculty of Civil Engineering, VSB – Technical University of Ostrava since 2013. The aim of this research it is to set fire resistance, thermal – technical properties and acoustical characteristics of crushed straw. There are described results of fire tests – flammability test and tests of single burning object (SBI). Subsequently there are referred results of thermal conductivity measurements, which were provided for different bulk densities of crushed straw.

Fire test of behaviour of timber-fibre concrete construction

30.1.2017 | Ing. Eva Šopíková, Ph.D., Ing. Anna Kuklíková, Ph.D., ČVUT Praha, Ing. Petr Vymlátil, Ph.D., Designtec Brno, prof. Ing. František Wald, CSc., ČVUT Praha, pracoviště UCEEB
The subject of this paper is a comparison of two experiments of timber-fibre concrete floors in fire, which consist of steel fibre reinforced concrete boards and glue-laminated timber beams. Main aim of this project is to assess the using of steel fibre reinforced concrete board, which work together with glue-laminated timber beams to increase fire resistance and investigate its behaviour in loaded construction.

Design of carpentry joints according to Eurocode 5

24.10.2016 | Ing. Bohumil Koželouh, CSc.,, soudní znalec
Compression joint with framed joint in combination – Ground rules for mortise and tenon joints – Load carrying capacity of mortise and tenon joints – Design examples.

Design of carpentry joints according to Eurocode 5

17.10.2016 | Ing. Bohumil Koželouh, CSc.,, soudní znalec
Ground rules for framed joint with notch – Compression joint with framed joint with notch – Consider of eccentric joint for framed joint with notch – Design examples

Spatial structure on the basis of wood solid panels

22.8.2016 | doc. Ing. Ján Kanócz, CSc., Ing. arch. Miroslava Mertová, Katedra architektúry, FU, Technická univerzita v Košiciach, Ing. Viktória Bajzecerová, PhD., Stavebná fakulta, Technická Univerzita v Košiciach
Structure created from solid wood wall and deck panels is characterized by a high spatial stability and rigidity. Results of ongoing research have shown that adding concrete layer to the wood deck creating the composite floor structure allows us to receive the structural wall system with increased efficiency.

Analysis model of carpentry joint

15.8.2016 | Ing. Martin Hataj, doc. Ing. Petr Kuklík, CSc., ČVUT Praha, UCEEB
The aim of this article is to compare 3D numerical models of traditional timber joint. Numerical model of the subjected carpentry joint includes material nonlinearities. Material model of wood presume elasto-plastic behaviour and has orthotropic – transversal isotropic property. The finite-element meshes introduced herein differ one from other by element type and their quantity applied, type of mapping and local density of mesh. Number of nodes and elements, calculation convergence speed, FEM solution exactness, symmetry and mapping of elements are observed.

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

Raised Heel-Trusses

26.6.2016 | Ing. Bohumil Koželouh, CSc., soudní znalec
One of the best techniques that builders can implement to boost energy performance in a home is raised-heel truss. Also known as energy-heel trusses, raised-heel trusses deliver cost-effective energy performance, especially when combined with continuous plywood or OSB sheating.

Monitoring the mechanical stress of wooden structures by the fiber optic sensors

13.6.2016 | Ing. Lukáš Velebil, Ing. Richard Zelený, Ing. Jan Včelák, Ph.D., doc. Ing. Petr Kuklík, CSc., Stavební fakulta, ČVUT v Praze
The paper describes a system of FBG (Fiber Bragg Grating) sensors and their integration into the beams of glued laminated timber for continuous monitoring and diagnostics of mechanical stress in building structures. The possibility of gluing the optical fibers into the timber structure and influence on manufacturing process of glued laminated timber on the glued fibers is studied. Laboratory tests including mechanical loading of examined samples were carried out to verify the correct operation of the sensors. Based on the measurement, a timber beam with embedded FBG sensors for the monitoring of the real construction have been manufactured.

Application of wood in exhibition halls at EXPO 2015

6.6.2016 | prof. Ing. Josef Chybík, CSc., Fakulta architektury VUT v Brně
The world exhibition EXPO 2015 proved from the creative and useful perspective that wood is a promising building material. We could see the use of wood on a number of exhibition objects representing countries from around the world. Even in the recent past that was not quite realistic. This was enabled by technological advances which created conditions for the implementation of bold ideas of architects associated with this renewable raw material. Along with the exhibition buildings, wood was used for the service utilities which provided comprehensive facilities of the exhibition grounds. In addition to wood, other natural materials such as rattan, bamboo and natural fibres were applied in some exhibition halls.

Designing of All-wood Carpentry Joints for Reconstruction of Historical Structures

16.5.2016 | Ing. Jiří Kunecký, Ph.D., Ing. Hana Hasníková, Ústav teoretické a aplikované mechaniky AV ČR, doc. Ing. Petr Fajman, CSc., ČVUT Praha, fakulta stavební, Ing. Jan Tippner, Ph.D., Mendelova univerzita Brno
The article introduces the new method “Lapped Scarf Joints for Historical Structures Repairs” that deals with design of the lapped scarf joint suitable for the reconstruction of valuable historical timber structures, with help of making the prosthesis for the damaged parts of the beams. The method is a result of the four-year research project supported by the Czech Ministry of Culture within NAKI program. Institute of Theoretical and Applied Mechanics AS CR, Faculty of Civil Engineering CTU and Faculty of Forestry and Wood Technology of Mendel University participated in the research.

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
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