Out-of-plane compressive performance of laminated bamboo grid sandwich panels

To investigate the out-of-plane compressive performance of laminated bamboo grid sandwich panels under different loading conditions, and to provide both theoretical foundations and experimental support for their lightweight applications in modern green prefabricated buildings.

This study focused on flat-pressed laminated bamboo grid sandwich panels fabricated from Phyllostachys edulis sourced from Taojiang County, Hunan Province. Two core configurations were designed: axial parallel-to-grain and axial perpendicular-to-grain. A total of 18 specimens were prepared (3 parallel specimens for each of the 2 core types under 3 loading conditions). Out-of-plane compression tests were conducted under concentrated, linear, and planar loads to systematically investigate their failure mechanism and mechanical properties.

The laminated bamboo grid sandwich panels exhibited significantly distinct failure modes under different loading conditions. Under concentrated load, failure primarily manifested as localized face-sheet fracture; under linear load, face-sheet fracture dominated; while under planar load, the predominant failure modes were web buckling and fracture. Axial parallel-to-grain core specimens demonstrated superior mechanical performance across all three loading conditions compared to axial perpendicular-to-grain specimens, with compressive strength increasing by 33.3%, 130.3% and 178.0%, compressive modulus increasing by 36.4%, 16.6%, and 25.2%, and energy absorption capacity increasing by 14.3%, 72.5% and 186.6%, respectively. As shown in the results, the load-displacement curves exhibited typical nonlinear characteristics, with axial parallel-to-grain specimens showing higher stiffness but lower ductility, while axial perpendicular-to-grain specimens displayed the opposite behavior.

The failure modes of specimens showed significant differences under different loading conditions (concentrated load, linear load, planar load). Meanwhile, the core type significantly affected the out-of-plane compressive performance of specimens, specifically showing that axial parallel-to-grain core specimens exhibited notably higher compressive strength, compressive modulus and energy absorption capacity than axial perpendicular-to-grain core specimens.