MASS ESTIMATION OF PILED ROUND BARS THROUGH VIBRATION TESTS

摘要

A simple method was developed to estimate the mass of each piled round bar using a vibration test. Specimens used in the tests were Japanese cedar (Cryptomeria japonica D. Don) round bars (diameter = 180 mm, length = 2000 mm) with a pith and a back split. Vibration tests were conducted, and the effect of sticker positions on the vibration test was investigated. The vibration tests were conducted for each piled round bar and the estimation accuracy of the vibration method with additional mass (VAM) was examined. By placing the round bar on the stickers, the resonance frequency of the longitudinal vibration was stable while that of the bending vibration decreased with the increase in the distance between the sticker and the specimen end and stabilized when this distance was greater than or equal to 0.2 l (l: specimen length). When the round bars were piled with no stickers, the bending resonance frequency could not be identified and the VAM estimation accuracy of the longitudinal vibration depended on the specimens. The estimation accuracy of VAM for the longitudinal vibration of the piled round bars while using stickers made of wood and rubber was superior to that without stickers. The estimation accuracy of VAM for the bending vibration was sufficiently high. These results were attributed to the reduction of the vibration restraint by the stickers and the contact between adjacent round bars.