Mechanical properties of laminated bamboo under off-axis compression

To investigate the compression performance of laminated bamboo, 210 laminated bamboo specimens were tested using seven different lamination angles. Six failure types were classified. All the specimens experienced elastic stage at the beginning of the loading process and then elastic-plastic stage. At the end of the elastic-plastic stage, specimens of 15 degrees, 30 degrees and 45 degrees immediately reached the ultimate bearing capacity, showing brittle failure, while other specimens entered a longer plastic stage before failure. The off-axis compression strength and the apparent elastic modulus both decreased with the increment of the angle. Two empirical formulas were proposed to predict the off-axis compression strength and apparent elastic modulus of laminated bamboo compared with several well-known failure criteria. The Poisson's ratio in A/C planes increased with the increment of the angle while in B/D planes, it increased and peaked at 30 degrees before decreasing. Based on Ramberg-Osgood relation, the compression and shear stress-strain curves were fitted.