The blast alleviation effects of a hybrid barrier system with triple energy absorbers

Blast walls on offshore topsides are designed to protect personnel and critical equipment. The traditional design that relies on the panel as the sole energy absorber is difficult to achieve the code compliances. While studies on dual absorber system such as foam cored sandwich panels overlook the boundary effects. This study investigates the blast alleviation effects of a hybrid barrier system with triple energy absorbers (i.e. panel, foam and springs), in which the foam and springs are placed at the supports to prevent weld rupture. Accordingly, a novel design concept is proposed by using flexible supports filled with polymethacrylimide foam and rotational springs, allowing the wall to slide/rotate a certain distance/angle to release the high stresses at supports and meanwhile dissipate blast energy through material deformations. The panel deflection, energy absorption and weld rupture of the proposed system are the focal points. An analytical model based on beam vibration theory and virtual work theory has been developed, in which the boundary conditions at each support are simplified as a translational spring and a rotational spring. Finite element method has been applied to corroborate the analytical model. In addition, the interaction effects between the three absorbers have been investigated through energy absorption breakdowns. In the end, a numerical comparison study with the traditional design has been presented to demonstrate the privilege of the proposed system in minimising weld rupture risk due to the high stresses being realeased through controlled displacements and rotations at supports.