Fundamental Research of an Evaluation Method of Splitting Failure in Timber III. Proposed fracture mechanism and evaluation method of splitting when loaded parallel to grain

摘要

The mechanism of splitting of timber loaded parallel to grain is not clear and it is difficult to evaluate the strength of timber under such loading. For splitting of drift-pinned joints with steel side plates loaded parallel to grain, an evaluation method was proposed by considering that splitting occurs when maximum bearing stress by drift pin to timber reaches its bearing strength. Based on this view, values of splitting strength estimated by calculation and analysis were compared with experimental values reported in the previous article. Taking the ends of the drift pin as free ends, the calculated values agreed well with experimental values of specimens with thickness of less than 60 mm. On the other hand, taking the ends of the drift pin as fixed ends, the calculated values agreed well with the experimental values of specimens with thickness of more than 90 mm. According to the method proposed in this research, increasing specimen thickness leads to greater differences between specimens with free and fixed ends. It is clear that restricting joint rotation has a large effect. Analytical and experimental values in any specimen are well matched because the restriction of rotation is set properly based on the results of the tests.