Design and experimental study of lightweight fireproof bidirectional bead bulkheads in a cruise ship

Abstract

The design of cruise bulkheads faces a challenge on the balance of lightweight, load-bearing capacity and fireproof performance. The existing steel stiffened bulkheads exhibit heavy weight and complicated manufacturing process, while lightweight (composite and aluminum) bulkheads suffer from high cost and poor load-bearing capacity. A lightweight design method based on the topography optimization theory, which can adaptively determine locations, numbers and topography of the bidirectional bead of sandwich bulkhead is proposed for cruise ships. Mathematical optimization formulations for bead topography design of sandwich bulkheads considering weight objective and strength and buckling constraints are established. Taking a fireproof bulkhead design in the superstructure of a cruise ship as an example, the design process based on the proposed method is demonstrated, including the fire protection design of insulation materials, the selection of design domains in the bead topography optimization, the definition of design variables, and the refined design of the final bead parameters. A full-scale lightweight bidirectional bead steel sandwich bulkhead (the specimen) is selected and manufactured by comparing with the stiffened bulkhead. Then a load-bearing fire-resisting test of the specimen designed is carried out. The test results show a weight reduction of 20.56% for the new designed bulkhead compared with the conventional one, and reached the fire-resisting divisions 60 class meeting the requirements of integrity, insulation and load-bearing. This design method provides a new way to alternatively design fire-resisting bulkheads.