Analysis of mini-jack technique for in situ measurement of strength

0477194 - ÚTAM 2018 RIV SE eng C - Konferenční příspěvek (zahraniční konf.)
Kloiber, Michal - Tippner, J. - Kunecký, Jiří - Sebera, V. - Milch, J. - Hrivnák, Jaroslav
Analysis of mini-jack technique for in situ measurement of strength.
Conference proceedings, ICTB 2017, 3rd International Conference on Timber Bridges. Skelleftea: RISE Research Institutes of Sweden, 2017. SP Rapport 2017:26. ISSN 0284-5172.
[International Conference on Timber Bridges, ICTB 2017 /3./. Skelleftea (SE), 26.06.2017-29.06.2017]
Grant CEP: GA MK(CZ) DG16P02M026
Klíčová slova: non-destructive testing * mini-jack technique * wood * in-situ testing * compression strength
Obor OECD: Construction engineering, Municipal and structural engineering

The paper presents a recently developed diagnostic technique for in situ determination of modulus of deformability (MODL) and conventional strength (CSL) parallel to the grain using the mini-jack inserted in bored hole. The mini-jack compression technique simulates the standard compression test, it is compared to that to examine its prediction strength (correlation coefficients). The paper shows an influence of moisture content of wood on experimental measurements using this technique. The measurement was carried out at spruce samples at three moisture contents of 12, 18 and 24%. The results of the tests prove a very good correlation of the strength determined by the proposed technique and wood density and strength determined at universal testing machine in compression parallel to the grain. The effect of the moisture content on the measurement by the mini-jack technique was proved to be significant. Beside that, the newly-developed instrument was also studied using digital image correlation (DIC) technique to analyze induced strains around the bored hole. This was studied on halved spruce samples. The DIC revealed symmetric character of the loading and significant differences between strains induced in tangential and longitudinal directions.
Trvalý link: http://hdl.handle.net/11104/0273570