3. Doktoritööd
Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/7081
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Sirvi 3. Doktoritööd Autor "Eesti Maaülikool" järgi
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Kirje Non-Destructive Assessment of Physico-Mechanical Properties of Structural Timber and Glulam(Eesti Maaülikool, 2016) Teder, Marko; Miljan, Jaan; Wang, Xiping; Eesti MaaülikoolAssessing the condition of load-bearing structures of any building, especially the old one, is an essential action to assure the safety of habitants. Timber, as a construction material, has been used for centuries and there are a lot of buildings with original timber elements worth of saving. Wood in these structures needs routine inspection for its condition and structural integrity. Deterioration of timber elements may often occur internally before any external signs of damage are visible. Thus there is a practical need for cost-effective and non-destructive inspection methods to obtain reliable data about the true condition of the structures and acquire scientific estimates of the residual load capacity of timber elements. There were two main goals in this study: 1) Investigate the feasibilities of the state-of-the-art NDT methods (resistance micro-drilling and stress wave (sonic and ultrasonic) propagation) for assessing the physical-mechanical properties of solid sawn timber and glulam, and the ability to detect local damages (e.g. cracks, decay) and delamination within the elements; 2) Put those non-destructive methods into practice through real timber structure inspection cases. The results revealed that, when applying micro-drilling method to existing timber structures, we expect to have a moderate correlations with wood density. The axial compression load has minor effect on resistance micro-drilling. Measurements of velocities by sonic and ultrasonic stress wave timing methods showed good potential of using them in field inspections for estimating the strength properties of the timber elements. In glulam assessment, all investigated non-destructive methods were found effective in detecting internal deterioration of the timber and the glulam components in structures. Resistance micro-drilling was not effective in detecting delamination in glulam. For field timber structure inspection, the assessment methods selected has to be less time consuming, easy to use, and reliable for field data collection. Condition assessment must contain a multi-approach that would include non-destructive methods as needed to fulfil the tasks of the project.