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Measuring strength and modulus of deformability of wood in compression parallel to the grain in a bored hole by a small jack\n
Kloiber, Michal
The publication is dedicated to the methodical description of the technical solution and the measurement of strength and modulus of deformability of wood in compression parallel to the grain in a bored hole by pushing apart grips of a small jack and loading the walls of the hole. The methodology presents the principles of the device usage and measurement result evaluation for the purposes of surveys of historical monuments and projects for their rescue or appreciation. Currently, there is no other method allowing determination of mechanical properties of wood, such as strength and modulus of elasticity in compression parallel to the grain, directly in the field without sampling. Therefore, the research was oriented to the development of a simple method, practically applicable for the purpose of structural-technical surveys of timber structures, in particular historical monuments. The resulting methodology meets the protection of the cultural heritage standards, in particular the requirement to minimize interference with the original material, while retaining high reliability of the determined wood mechanical properties of wood.
Fulltext: content.csg -  PDF
Plný tet: 0453514_2015_Kloiber_Mereni_pevnosti_a_modulu_pretvarnosti_dreva_CM_NAKI-001 - PDF
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The influence of deformation of the frame of testing device on the accuracy of Brazilian test and indirect assessment of Young modulus
Major, Štěpán ; Vavřík, Daniel ; Kocour, Vladimír ; Bryscejn, Jan
This article deals with determination of mechanical properties based on indirect measurements of brittle building materials like stones using portable device. Due to the fact, that the material samples may change their properties during transportation, it is preferred to test samples on site. For these reasons, portable testing device was developed. The testing machine operates on the split test principle. The device also shall to serve for estimation of other mechanical characteristics of the tested material, such as Young's modulus, compressive strength or flexural strength, etc. This paper concentrates on the effect of deformation of frame on the accuracy of indirect determination of mechanical properties.
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Diagnostic of timber structures
Kloiber, Michal
Diagnostic of timber structures is a special field of engineering, that is focused on timber assessment, evaluation of defects and assessing the safety and reliability of existing wood structures. Special task is the diagnostic of timber structures in historical objects. In such cases, usually, we can not use the standard methods for determining the mechanical properties of wood, it is necessary to meet the requirement of minimum intervention into the object structure. The aim of the presentation is to inform the professional audience about the possibilities of application of diagnostic methods, which provide the required information with a high consideration for preservation of the original material and the object design concept. Quality diagnostic uses very sophisticated methods and can be costly, however, often provide accurate data even in low invasiveness, which is valued at the historical object diagnostic. Overall cost of the technical and diagnostical survey of structure can be reduced by cost savings on demolition and repair works.
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Research Report on Condition Assessment of Wood-destroying Damage to Log Walls of a Landless Person's Cottage of Leskovec (orig. No. 70) and a Cottage of Lužná (orig. No. 28) now in the Museum in Rožnov pod Radhoštěm
Kloiber, Michal ; Hrivnák, Jaroslav ; Bláha, Jiří
The subject of the research report was to assess the condition of and identify the wood-destroying damage to the walls of a landless person's cottage of Leskovec and a cottage of Lužná, two log structures that are part of the exhibition at the Wallachian Museum in Rožnov pod Radhoštěm. The report focused on locating points, classifying the degree of damage, determining the extent of concealed attack by the means of non-destructive devices, specifying whether wood is subject to a fungal attack (mycological damage) or insect attack (entomological damage) and drawing the results obtained in the plan documentation. The report was based on direct and mediated visual observation using an endoscope and mainly on measurements taken using a resistance microdrilling device and also on ascertainment of mechanical properties of wood using expanding jaws in the borehole. Based on the results, specific procedures for rehabilitation measures were designed and elements designed for structural rehabilitation were marked in the drawing documentation.
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Research Report on Condition Assessment of the Holy Ghost Tower's Roof Frame in Telč
Bláha, Jiří ; Kloiber, Michal ; Frankl, Jiří ; Buzek, Jaroslav
The subject of the research report was to assess the condition of and identify the range of wood-destroying damage to the roof frame of the Holy Ghost tower in Telč focused on locating critical points, classifying the degree of damage, determining the extent of concealed attack by the means of non-destructive devices, specifying whether wood is subject to a fungal attack (mycology) or insect attack (entomology), including the drawing of the results obtained in the drawing documentation of the existing condition of the roof frame. Based on the results, specific procedures for rehabilitation measures were designed and elements designed for structural rehabilitation were included in the drawing documentation. The report is based primarily on direct and mediated (endoscopic) visual observations supplemented by measurements using a resistance microdrilling device.
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Research Report on Condition Assessment of Wood-destroying Damage to Tie Beams, Threshold Beams, Struts and Wall Plates of the Belfry Structure of the White Tower in Hradec Králové
Kloiber, Michal ; Hrivnák, Jaroslav
The subject of the research report was to assess the condition of and identify the range of wood-destroying damage to the tie beams, threshold beams, struts and wall plates of the belfry structure in the White Tower in Hradec Králové. The report focused on locating critical points, classifying the degree of damage, determining the extent of concealed attack by the means of non-destructive devices and drawing the results obtained in the drawing documentation. The research report was based on direct and mediated visual observation using an endoscope and mainly on measurements taken using a resistance microdrilling device and also on ascertainment of mechanical properties of wood using expanding jaws in the borehole. Based on the results, a rehabilitation measure was designed and elements designed for structural rehabilitation were indicated in the drawing documentation.
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New devices for diagnostics of historical structures
Hasníková, Hana ; Kloiber, Michal ; Zíma, Pavel
Two new devices developed at ITAM AS CR for non-destructive testing of materials, especially from historical structures, are presented below. So called microtube is a semi-automatic portable tool for water absorption measurements. The natural stones, mortars and other porous materials can be measured and it is very useful to assess the efficiency of various hydrophobic treatments used within the restoration also. The diagnostic device for in-situ assessment of timber enables direct determination of conventional compressive strength and modulus of deformation in arbitrary depth along timber profile. The semi-destructive method causes a very gentle damage on the structural members.
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New devices for diagnostics of historical structures
Hasníková, Hana ; Kloiber, Michal ; Zíma, Pavel
The aim of the paper is to present a few new devices that were developed at ITAM AS CR for non-destructive testing of materials, especially those from historically valuable structures. So called microtube is a semi-automatic portable tool for water absorption measurements. It consists of box with microprocessor where the time is recorded and the plastic “pistol” – a part that is in contact with the material surface and where the scaled micro-tube is fixed on. The natural stones, mortars and other porous materials can be measured by the microtube; it is very useful to assess the efficiency of various hydrophobic treatments used within the restoration. The diagnostic device for in-situ assessment of timber in existing structures enables direct determination of conventional compressive strength and modulus of deformability in arbitrary depth along timber profile. The semi-destructive method causes a very gentle damage on the structural members.
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