Evaluation of the in-plane shear properties of bamboo strips (<i>Phyllostachys edulis</i>) with the Iosipescu test and theoretical models based on composite mechanics

Abstract Engineered bamboo products have been increasingly used in construction. However, there are few studies on its shear performance. Thus, the shear properties of bamboo lamina strips were investigated by the Iosipescu shear test. This study aimed to obtain the shear stress-strain curves and the lamina’s corresponding strength and modulus values, which can be used to design and model bamboo structural components. With this goal, 120 specimens were tested, considering the effect of loading directions on bamboo fiber, the existence of bamboo nodes, standard thickness, and fiber volume fraction. The characteristic shear strength values were also estimated based on the test data. Results show that the bamboo nodes and standard thickness have a negligible effect on the shear modulus and strength values. In contrast, the shear properties were determined by the loading directions and fiber volume fraction. The specimens’ measured shear strength and modulus loaded parallel/perpendicular to the bamboo fiber direction were about 10 MPa/15 MPa and 550 MPa/1000 MPa. The fiber and matrix-dominate failure modes were noticed for the specimens, and the unidirectional bio-fiber reinforced composite theoretical model could be used to predict the modulus values of fiber-dominate samples based on the measured volume fraction of the fiber.