Test on in-plane stability capacity of bamboo arches with steel hoop-carbon fiber composite joints

Abstract: Carbon dioxide in the air is absorbed in the growth process of bamboo, which is beneficial to the purification of air and reducing the content of greenhouse gases in the atmosphere. Energy consumption in manufacturing process of bamboo structure is much less than other kinds of common building structure, such as concrete structure. In addition, bamboo structure can be naturally degraded without adding any pollution to environment when its service expires. Used as building materials, bamboo is beneficial with natural environment in any stages including growth, processing, service and disassemble. Therefore, bamboo is regarded as an eco-material. According to the mechanical properties of bamboo tubes, a new steel hoop-carbon fiber composite joint was designed to connect irregular size of bamboo pieces. With a specific method, the connected long straight bamboo member was curved into the shape of arch and eventually such connection led to form a new bamboo arches which was named as steel hoop-carbon fiber composite joints bamboo arches or SFJ. SFJ bamboo arches possess advantages of simply joints constitution, and much less splitting failure incidence in joint region and can be used in large span and light arch structure such as landscape architectures, roof of buildings, greenhouses, temporary sheds. In general, the shape of large span bamboo arches is much slender than other common structures, and as such it is prone to instable especially when bamboo tube is in the stress state of compression. For this reason, the ultimate state of bamboo arch with enough out-of-plane supports is usually in-plane overall instability. Therefore, it is necessary to carry out reasonable analyses of in-plane stability capacity of SFJ bamboo arches to ensure structural safety. Two 10 meters span bamboo arch specimens were built for static load tests in order to study the ultimate bearing capacity, deformation capacity and connection performance of bamboo arches. Result of tests demonstrated that stress state of most bamboo sections and joints was in elastic stage before overall instability, while strain and bending curvature increased quickly after instability and induced splitting failure in the region with maximal bending curvature. The new bamboo arches possessed the character of excellent ductility, larger deformation capacity and favorable connection performance. The ultimate state of the new bamboo arches was in-plane overall dissymmetry instability and failure region of bamboo material was close to the new composite joints. For the promising performance of composite joints in the whole process of loading, further study on mechanical mechanism and bearing capacity of the new composite joints is necessary so as to promote the application of SFJ bamboo arches. According to the large deformation character of bamboo arches in whole loading process, geometry and material nonlinear must be taken into account in the finite element analysis of this new kind of bamboo arches. The results of FEA(finite element analysis) have favorable agreement with tests results, and FEA can be used in the analysis and design of this new kind of bamboo arches.