Splitting Capacity Characterization of Bamboo Culms

The history of engineering knowledge with regards to bamboo is surprisingly recent, with the major work on bamboo having been completed by Janssen (1981) and Acre (1993) of the University of Eindhoven, The Netherlands. In their research, both noted that splitting is the dominant limit state in structural applications, which agrees with the author's experience (during our May 2008 visit to India) and that of other researchers. It is because of this dominant limit state that this research focused on the development of an appropriate method of characterizing the splitting strength of bamboo culms. This document focuses on developing and calibrating an appropriate (but simple to conduct) test method for assessing the splitting capacity of full culms. The proposed split-pin fracture test is founded on a fundamental fracture mechanics approach. This method, while simple to conduct, can account, in a consistent manner, for the high degree of variability present in bamboo geometric and material properties. In order to demonstrate the validity of the proposed test method, a series of tests were performed on a sample of Bambusa Stenostachya (Tre Gai) bamboo. In addition to the proposed fracture test, shear and compression tests were performed in accordance with existing ISO standards (ISO 2004b). Of the three test types performed, the compression test had the lowest variability, the shear test had the highest, and the proposed fracture tests had a variability that fell between the two. Thus the fracture test demonstrated that it yields reliable results.Utilizing the values obtained from both this series of tests as well as those carried out by other institutions, a comparison of common design values was made between Tre Gai and the select-structural grade of two commonly encountered woods, Douglas Fir and Southern Pine. While the design values for bamboo obtained from different institutions varied considerably, Tre Gai generally exhibited performance superior to that of the two timber species referenced. It can be concluded that Tre Gai, when grown, harvested, and preserved correctly, is a competitive, or in some cases, a superior alternative to wood.