A nonlinear beam-spring-beam element for modelling the flexural behaviour of a timber-concrete sandwich panel with a cellular core

Timber-concrete composite panels are commonly used as a sustainable alternative for reinforced concrete floor construction systems. Their performance also continues to advance with new approaches to interfacial shear connection and layer composition, for example as three-layer sandwich panels with a concrete compressive face layer, timber tensile face layer, and a cellular core. Due to significant difference in stiffness of the layers, such sandwich panels demonstrate large transverse shear deformations when subjected to bending. Existing finite element modelling techniques, relying on traditional shell or solid elements, can become computationally expensive when simulating the behavior of sandwich panels. This paper presents a new composite element for simplified numerical modelling of sandwich panels, greatly reducing the computational effort. The proposed element comprises two face layers connected by an inter layer, with face layers considered as beams and the inter layer considered as springs. A numerical model was developed using the proposed element and was validated against finite element results of linear sandwich beams and experimental results of nonlinear, cellular-cored timber-concrete sandwich panels.