Structural performance of sandwich steel-concrete-steel composites utilising engineered cementitious composites

Due to the benefits of Steel-Concrete-Steel composites (SCS) and the improved mechanical characteristics of Engineered Cementitious Composites (ECC), utilising ECC as a core material for sandwich composite systems is expected to improve system performance. This paper investigates the ability to improve the flexural behaviour of composite structures by placing an ECC core sandwiched between two steel plates, which are interconnected by bolted connectors. An ECC core can sustain more flexural stresses and provide stronger lateral confinement to the bolts. Push-out tests confirm that the shear transfer capability of a bolted connector embedded in ECC is superior to those embedded in normal concrete (NC) in achieving composite action between the steel plate and the core. Four sandwiched one-way slabs were tested to evaluate their flexural performance when subjected to static point loads. The parameters investigated included the core material and the shear connector diameter. Using the analytical models available in Eurocode 4 and the literature for steel-concrete-steel sandwiches, theoretical analysis was conducted to predict the shear connector's strength and the slab's flexural behaviour, comparing them with the experimental results. The predicted capacities show general agreement with the test output, concluding that the available models for NC sandwiches can be followed for ECC. Test evidence also shows that the inclusion of ECC as a sandwich core significantly increases the flexural capacity, as well as its post-peak ductility.