Sandwich assemblies of composites square hollow sections and thin-walled panels in compression

Sandwich structures were built up by two glass fibre reinforced polymer (GFRP) thin-walled panels and square hollow sections (SHS) in between through adhesive bonding or mechanical bolting. Experiments in compression were conducted in order to understand the failure modes including global and local buckling, load-bearing capacities, load-displacement curves and load-strain responses. Accordingly the effects of different connection methods and different spacing values between the SHS sections were clarified. Sudden debonding failure between GFRP panels and inner SHS columns was found on adhesively bonded specimens; while mechanically bolted specimens showed evident lateral deformation and progressive failure until the ultimate junction separation failure on the GFRP SHS columns. Local buckling was found on GFRP thin-walled panels of specimens with a larger spacing between the two SHS sections. Finite element analysis and analytical modelling were performed to estimate the load-displacement curves and the critical stress for the local buckling on GFRP thin-walled panels, where consistent agreements with experimental results were received.