Steel Sandwich composites have been used widely in offshore industry. However, the use of steel is unsustainable and require expensive maintenance. Glass-Fibre-Reinforced Polymer plates are potential replacements as they possess high tensile strength and many advantages. In this research, GFRP sandwiches with one and two-face configurations and Engineered Cementitious Composites (ECC) as the core are constructed to investigate their ultimate behaviour against bending. Mechanical Connectors are used as shear-resistant elements. Moreover, the effect of shear span to depth ratio (a/d) is investigated. Results show that load resistance increases with thickness of ECC core. However, the use of GFRP plates in the compression zone of section rendered ineffective due to the fact that GFRP cannot act in compression. All slabs tested have not experienced any diagonal shear cracks while all crack formed were flexural. All slabs showed a significant deflection capacity and ductility prior to failure. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.