The effect of loading orientation on the compressive bearing behavior of bamboo engineering composites

Bamboo engineering composites (BECs), emerging as a prominent force in the realm of green sustainable building material, have expanded beyond traditional application in structural engineering. These materials can now be processed into load-bearing components such as beams and columns. However, owning to variations in fundamental units, formation processes and application scenarios, the mechanical bearing behavior of BECs exhibited significant diversity. Particularly, there was limited research regarding the tensile and compressive bearing behaviors of these components when employed as beams and columns under different load orientations, which considerably hindered their broader promotion and application. In view of this, this study focused on two typical BECs, namely bamboo scrimber (BS) and glue-laminated bamboo (GLB), examined their compressive bearing capacities and failure modes under various load orientations. The results showed that the compressive strengths of BS gradually decreased as the orientations increased from 0° to 90°. Conversely, the compressive strengths of GLB initially decreased and then increased, with the lowest strength observed at 45°. As the loading orientations shifted from 0° to 90°, the failure modes of BS evolved from initial wrinkling to progressive shearing, culminating in crushing failure. In contrast, the failure modes of GLB transitioned from diagonal buckling, followed by adhesive layer cracking, and ultimately resulted in overall crushing. The Hankinson formula and the maximum stress theory were respectively utilized to predict the compressive strengths and failure modes of the two BECs. The critical points for the failure modes of BS under various load orientations were identified as 21° and 48°, respectively. For GLB, these angles were determined to be 14° and 72°. These findings offered a fundamental theoretical basis for the scientific design and rational application of the BECs in building engineering, as well as for optimizing preparation processes. • The compressive bearing capacities of the two BECs were systematically investigated. • The failure mechanisms of the two BECs under various load orientations were analyzed. • Models derived from the Hankinson formula were proposed to predict compressive strength. • The critical thresholds for failure mode transitions under diverse load orientations were identified.