A comprehensive study on bamboo cracking: Exploration of the cracking process and factors influencing cracking

Due to its unique cylindrical structure and excellent bending resistance, bamboo has demonstrated great potential in the bamboo construction industry. However, the cracking of round bamboo culm is a critical issue that compromises the structural integrity of bamboo materials, posing potential risks to their strength and stability. Therefore, in this work, dynamic crack growth imaging was employed to document the entire development process of bamboo cracking. Drying-induced cracking tests and in situ observation were utilized to investigate the cracking factors of bamboo, including diameter, height, nodes, and grooves. The results indicated that cracks always originate in bamboo green and progressively extend towards the bamboo yellow. At the same time, bamboo of different sizes, such as different outer diameter, height, nodes, and grooves, exhibited varying degrees of cracking. As the diameter increases, cracks with larger openings become less frequent. In terms of height, bamboo specimens with 4-cm height were the most susceptible to cracking. It is worth noting that as the height increases, the degree of cracking in the bamboo shows a decreasing trend. The bamboo node can effectively provide structural support and enhance resistance to cracking. Grooves in bamboo tend to create stress concentrations, making these areas more prone to cracking. The laws and causative factors of bamboo cracking elucidated in this article are expected to serve as a theoretical foundation for studies on cracking resistance in dual-phase structures.