Studded bond enhancement for steel-concrete-steel sandwich shells

A double-wall steel-concrete-steel (SCS) composite vault has been proposed for the “Singapore Cone” Arctic offshore structure. The SCS vault performs well under uniform pressure, but can fail prematurely under partial asymmetric loading. These shells will often experience a punching shear failure or flexural steel plate buckling which is exacerbated by the loss of bond between the steel wall and concrete interface. In this study, a construction friendly method using an array of welded mini studs to improve the steel–concrete interfacial bond is proposed and studied. Two workable Type I Portland cement grout mixes are tested as the bulk material: plain, and fiber reinforced. Studded concrete steel interfaces were tested under mode I interface peeling, and mixed mode shear. The small scale tests were also modeled with the nonlinear finite element analysis software ABAQUS, and the numerical results were compared against the laboratory experimental results. After qualitatively matching the computational results with experimental results, a large scale SCS prototype is modeled and designed, with working stresses limited to the elastic range. Mode I peeling ultimate strength of 0.46fc′ was used for the prototype analysis, with mixed mode shearing limited by bulk concrete away from the studded bond surface.