Parallel-to-grain tensile mechanical behavior of laminated bamboo lumber for bolted connections

In this study, the tensile mechanical properties of bolted laminated bamboo lumber (LBL) loaded parallel to the grain were investigated under the influence of end distance and bolt spacing according to ASTM D5652-95. A total of 32 specimens were tested and the bearing capacity was calculated based on the 5% D offset method. The test results showed that: end distance and bolt spacing both regularly affected the initial stiffness and bearing capacity of the specimens, while there was no significant effect on the yield stiffness; with the enlargement of end distance and bolt spacing, the ductility ratio gradually increased and tended to stabilize, and the failure mode shifted from brittle failure to ductile failure, resulting in the recommended minimum size requirements for bolted LBL as follows: 8 times the bolt diameter for the end distance and 7 times the bolt diameter for the bolt spacing. The bolted connection bearing capacity of different materials as well as that obtained by different calculation methods were compared with the experimental results, allowing the empirical equations for predicting the yield load of bolted LBL to be put forward.