Development of SCS Sandwich Composite Shell for Arctic Caissons

摘要

There is a wide range of offshore structures which may be constructed by either steel or concrete materials to be used in the arctic region, such as steel tower platforms, caisson-retained islands, shallow-water gravity-base caisson, jack-up structures, bottom-founded deep-water structures, floating structures, well protectors, seafloor templates and breakwaters. One common feature of these structures is that they must be able to resist the high lateral forces from the floating ice and transmit these forces to the foundation. This study explores the use of Steel-Concrete-Steel (SCS) curved sandwich system for arctic caisson structures. SCS sandwich system, which combines the beneficial effects of steel and concrete materials, has promising benefits over conventional plates and stiffeners design and heavily reinforced concrete design because of their high strength-to-steel weight ratio and high resistance to contact and impact loads. Shear connectors have been proposed to provide bonding between the external steel plates and high-performance cementitious core materials. Finite element analyses and large-scale test results showed that SCS sandwich panels without mechanical bond enhancement are vulnerable to interfacial shear failure and impairment of structural integrity when subject to shrinkage and thermal strains, accidental loads, and impact. The proposed SCS sandwich system features mass-produced mechanical shear enhancement and/or cross-ties. It can reduce structure complexity, particularly in the number of weld joints which are prone to fatigue, hence increasing service life, cutting down the cost of fabrication, and reducing the manpower cost to operate, inspect, and maintain the structure in the long run. Considering local ice load, the punching shear and shell bending strength of the SCS sandwich composite shell is studied experimentally. Test results showed that the SCS sandwich panels, which are designed using the ISO ice load, are capable of resisting the localized contact and punching loads caused thereby. There is a wide range of offshore structures which may be constructed by either steel or concrete materials to be used in the arctic region, such as steel tower platforms, caisson-retained islands, shallow-water gravity-base caisson, jack-up structures, bottom-founded deep-water structures, floating structures, well protectors, seafloor templates and breakwaters. One common feature of these structures is that they must be able to resist the high lateral forces from the floating ice and transmit these forces to the foundation. This study explores the use of Steel-Concrete-Steel (SCS) curved sandwich system for arctic caisson structures. SCS sandwich system, which combines the beneficial effects of steel and concrete materials, has promising benefits over conventional plates and stiffeners design and heavily reinforced concrete design because of their high strength-to-steel weight ratio and high resistance to contact and impact loads. Shear connectors have been proposed to provide bonding between the external steel plates and high-performance cementitious core materials. Finite element analyses and large-scale test results showed that SCS sandwich panels without mechanical bond enhancement are vulnerable to interfacial shear failure and impairment of structural integrity when subject to shrinkage and thermal strains, accidental loads, and impact. The proposed SCS sandwich system features mass-produced mechanical shear enhancement and/or cross-ties. It can reduce structure complexity, particularly in the number of weld joints which are prone to fatigue, hence increasing service life, cutting down the cost of fabrication, and reducing the manpower cost to operate, inspect, and maintain the structure in the long run. Considering local ice load, the punching shear and shell bending strength of the SCS sandwich composite shell is studied experimentally. Test results showed that the SCS sandwich panels, which are designe