WOOD RESEARCH Volume 64, Number 3, 2019
Liuyang Han, Xiu Zhao, Haibin Zhou, and Xiuqin Luo

Reliability analysis on compression strength property of chinese larch visually-graded dimension lumber

The reliability analysis method was investigated in this study to obtain design values of ultimate compression strength parallel to grain (UCS) of Chinese larch visually-graded dimension lumber of common size. A total of 748 lumber samples of 40 by 90 mm were tested for static full-size compression strength according to Chinese National Standards’ requirements of the reliability index. The goodness of fit for the UCS distribution of four visual grades was analyzed and the first-order second-moment reliability analysis under different load cases was performed based on all the test data. The log-normal distribution was the optimizing fitted distribution of the compression strength of Chinese larch dimension lumber. Design values of the compression strength for grades Ic, IIc, IIIc and IVc were suggested for the minimum reliability index. These design values will be recommended to the standard committee of Chinese National Standards.

WOOD RESEARCH Volume 64, Number 2, 2019
Shuo Xue, Haibin Zhou, Xiaona Liu, and Weibin Wang

Prediction of compression strength of wood usually used in ancient timber buildings by using resistograph and screw withdrawal tests

Ultimate compression strength parallel to grain (UCS) of wood is one of important performance to evaluate the structural security of old wood buildings. Poplar wood (Populus tomentosa Carrière), Chinese larch wood (Larix gmelinii (Rupr.) Kuzen.) and Chinese fir wood (Cunninghamia lanceolata (Lamb.) Hook) were selected as the models in this paper. The aim of study is to predict UCS of wood by using resistograph and screw withdrawal methods. Compared with the screw withdrawal method (SW), resistograph method (RM) is generally more reliable, but because of the expenses involved, SW should also be considered as a much cheaper alternative. The results showed that the correlation coefficient between the RM and the UCS ranged from 0.5 to 0.7. The correlation coefficient between the double-start thread screw withdrawal force (SWDST) and the UCS distributed from 0.1 to 0.65, while the values of coefficients for the singlestart thread screw withdrawal (SWSST) differed from 0.4 to 0.65. In screw withdrawal method, greater pitch of screw resulted in higher correlation coefficient.