Numerical investigation of the flexural behaviour and composite action of reinforced concrete sandwich panels (RCSP)...

Conventional unreinforced brick masonry walls pose significant sustainability and seismic vulnerability challenges due to excessive resource consumption and self-weight. Reinforced Concrete Sandwich Panels (RCSP) with Expanded Polystyrene (EPS) core present a promising alternative, offering similar functional benefits while being lightweight, sustainable, and exhibiting enhanced seismic performance. This study investigates flexural behaviour of RCSP using validated three-dimensional nonlinear finite element model developed in Abaqus/Explicit, demonstrating close agreement with experimental results in terms of ultimate load capacity, crack initiation and propagation, and failure mechanisms. A systematic parametric study evaluated the influence of shear connector type, spacing, diameter, Welded Wire Mesh (WWM) size, EPS core thickness, and longitudinal reinforcement. Among connector types, Double-Truss Shear Connectors (DSC) increased the ultimate load capacity by up to 12-18% and improved post-peak ductility compared to orthogonal and Single-Truss Shear Connectors (SSC). Reducing connector spacing from 150 to 75 mm enhanced the ultimate load capacity by approximately 8.9%, with negligible change in failure mode. Increasing WWM diameter from 3 to 6 mm resulted in significant increase in flexural strength of up to 102.8%, indicating strong dependence on reinforcement stiffness. Variations in EPS core thickness showed less than 3% change in flexural capacity, confirming its negligible structural contribution under bending. Inclusion of additional longitudinal reinforcement (6 mm Fe500 bars at 160 mm spacing) increased ultimate load capacity by 40.5% and significantly enhanced ductility. These findings provide critical insights into the governing parameters affecting composite action and offer design-oriented recommendations for optimizing RCSP systems as lightweight, sustainable, and seismic-resilient alternatives to conventional masonry walls.