Behavior of sandwich wall panels with GFRP face sheets and a foam-GFRP web core loaded under four-point bending

In this paper, a simple and innovative sandwich panel with GFRP face sheets and a foam-GFRP web core (GFFW panels) is developed. An experimental study was carried out to validate the effectiveness of this panel for increasing the bending strength. The effects of web thickness, web spacing, web height and face sheet thickness on bending stiffness and energy dissipation were also investigated. Test results demonstrate that compared to the normal foam-core sandwich panels, a maximum of approximately 640% increase in the ultimate bending strength can be achieved. Meanwhile, the bending stiffness and energy dissipation can be enhanced by increasing web thickness, web height and face sheet thickness. An analytical model was developed to predict the ultimate bending strength of GFFW panels. The formulae to calculate the equivalent bending stiffness, shear modulus and mid-span deflection were also derived. A comparison of the analytical and experimental results showed that the analytical model accurately predicted the ultimate bending strengths and min-span deflections of the GFFW panels under four-point bending. Furthermore, the finite element analysis was extended to nvestigate the effects of foam density and shear span-to-depth ratio which were not considered in the tests. The numerical results revealed that increasing foam density and decreasing the shear span-to-depth ratio can improve the bending strength and stiffness of the panels.