The Centre for Frontier Engineering Research (C-FER) has just completed a research program devised to assess the shear capacity of a particular composite wall configuration subjected to combined in-plane and transverse loads. The testing program has demonstrated that, as in conventional reinforced concrete systems, the transverse shear capacity is significantly enhanced by coexistent in-plane compression. However, unlike conventional reinforced concrete systems, the transverse shear capacity does not appear to be adversely effected by even moderately high levels of coexistent in-plane tension. This paper presents the test results, attempts to explain the observed behaviour in the context of upper bound plasticity theory, and provides a method of design.


The peripheral wall system for an Arctic Offshore structure must be designed to resist massive transverse loads caused by ice pressure. A cost-effective approach to resisting these forces is the use of composite (steel-concrete) sandwich wall elements in the peripheral wall system. The sandwich composite system consists of two continuous steel plates enclosing a concrete core to which they are fastened by some mechanical means. Research on such wall systems as summarized by Adams et al. (1988) has shown that they have high flexural and shear capacities and very ductile failure modes, resulting in a large capacity to absorb energy. In application, the peripheral wall design process is complicated by the fact that, addition to transverse loads caused by ice pressure, significant in-plane loads, both tensile and compressive, can be generated by non-orthogonal support wall configurations, differential platform settlements and thermal gradients. However, the internal load transfer mechanism associated with sandwich composites can be significantly different than that of ordinary reinforced concrete (Adams et al. 1987, Gerwick and Berner 1987, O'Flynn and MacGregor 1987) hence the need to establish ultimate strength relationships appropriate to this relatively new structural system.

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