Construction and failure analysis of ultra-light GFRP fluted-core sandwich protective structures

Abstract Pultruded glass fiber reinforced polymer (GFRP) fluted-core sandwich panel is easily made and is a lightweight construction for protective structures. Blast-resistant doors are designed and constructed through combining three pultruded fluted-core sandwich panels framed by steel beams. With weight of 98.34 kg, the composite door is much lighter compared with traditional steel and concrete protective doors. Blast resistances of the composite protective doors are investigated by explosion testing. In current research, when the scaled distance is not smaller than 1.494 m/kg1/3, the door panel exhibits excellent anti-blast ability without any damage. When the scaled distance is less than 1.357 m/kg1/3, the structure damage is firstly characterized by the fluted-core shear and finally featured by the flexural failure of the delaminated sandwich panel. Including the deflection induced by the shear deformation of the fluted-core, dynamic one-way sandwich slab theory is proposed to predict the dynamic responses. The predictions are in agreement with the experimental results with acceptable errors. The dynamic theory can predict the critical scaled distance for the composite door based on core-shear failure criterion and the prediction is well consistent with the experiments. An equivalent static load model is suggested. Through the research, it is concluded that constructing protective door through pultruded GFRP fluted-core sandwich panels is a convenient, weight-saving and cost-saving way.