The study of minimum distance base on shear strength on connection system of raw bamboo

Abstract The connection system of raw bamboo needs to be considered to apply bamboo as a structural material. Raw bamboo has the characteristics of holes and nodes so that the minimum distance of connecting devices such as bolts on the connection system needs to be known. The minimum distance for a single bolt in a bamboo culm has been determined based on previous research, while each bamboo culm typically requires more than one bolt. In this study, an analysis of bamboo’s mechanical properties, namely shear strength and bearing strength, was conducted to determine the bolt spacing in raw bamboo connections before tensile testing was conducted on the culms. The results of the study showed that the connection system of raw bamboo with the variation in bolt-to-end distance of the bamboo without nodes for two bolts on a bamboo culm requires a total distance of 7 D with variations of 1) 3D and 4D and 2) 5D and 2 D with D is the diameter of the bolt. Furthermore, the recommended spacing between bolts in a connection system using two bolts is 4D, or 4 times the bolt diameter. Based on the results of this study, it can be concluded that the shear stress and bearing stress parallel to the fibers of raw bamboo material are able to analytically predict the critical distance obtained experimentally with precise accuracy.