Mechanical behaviour of rigid-flexible combined structures: Aluminium-inflated membrane beams for application in floating photovoltaic platform

This study aims to investigate the bending and failure behaviour of aluminium-inflated membrane beams for their applications in floating photovoltaic platforms. Four-point bending tests are conducted for a range of inflated pressures and two different deck heights to assess their effect on structural stiffness and ultimate bearing capacity. Meanwhile, the surface-based fluid cavity method is employed to develop the finite element model with the material properties determined by independent coupon-level tests. The bearing capacity of the aluminium-inflated membrane beam is positively correlated with the internal pressure and deck height. The midspan strain distribution is similar to those of the traditional four-point bending beam with the upper part undergoing compression and the lower part experiencing tension, however, the structural behaviour at the failure stage is different. Failure typically occurs due to localised depressions at the loading points on the aluminium deck, ultimately leading to structural failure. The numerical model closely matches the experimental data for the initial inflated and bending configurations, exhibiting a deviation of only 0.10 % to 0.46 % in diameter and 0.32 % to 5.57 % in equivalent bending stiffness. A parametric study shows that the loading properties of the beam are more sensitive to the internal pressure than the deck height and thickness.