On the share resistance of ferritic stainless-steel composite slabs

Steel-concrete composite slabs have proved a promising solution in the building and construction industry due to their excellent mechanical properties. Generally, these composites are prepared by pouring concrete onto galvanized steel decks. The choice of the type of steel, however, depends on the environmental conditions. To achieve optimum functions of steel-concrete composite slabs, understanding of the various failure modes is highly desirable. Among the available failure mode, longitudinal shear is the most prevalent. It results in a shear connection between the composite slab and the steel deck. This connection is influenced by several parameters such as spacing, material type, and size and thus determines the properties of the resultant composites.

Stainless steels and particularly ferritic stainless steels have been identified as a promising solution for fabricating stainless-steel composite slabs owing to its excellent mechanical and corrosion resistance properties as well as effective cost. Alternatively, several methods have been developed to investigate the longitudinal shear resistance of stainless-steel composite slabs. Presently, partial shear connection and m-k methods are commonly used even though they are based on the full-scale tests due to unavailability of pure analytical methods. Unlike in them m-k method, the sear longitudinal strength obtained in partial shear connection has physical meaning thus attracting researchers’ attention.

Recently, KU Leuven researchers: Dr. Kathleen Lauwens, Dr. Maarten Fortan and Professor Barbara Rossi in collaboration with Itsaso Arrayago and Dr. Enrique Mirambell from Universität Politècnica de Catalunya, Department of Civil and Environmental Engineering experimentally assessed the longitudinal shear resistance of stainless steel-composite slabs based on the partial shear connection technique. The composite was particularly made of EN1.4003 ferritic stainless steels. Their work is currently published in the research journal, Construction and Building Materials.

In brief, the research team started by cross-examining the available full-scale tests conducted on composites slabs. Secondly, four stainless steel composite slabs were fabricated using the same production method. Next, the slabs were tested using EN 1994-1-1guidelines after which the chemical bond formed between the concrete and steel deck was removed by a cyclic loading less than 5000 cycles. They further examined the influence of the cyclic loading on the bending moment of the composite. Based on the obtained results, the behavior of the stainless-steel slabs was then compared to that of galvanized steel.

The authors observed that all four sample composite slabs failed due to longitudinal shear. Consequently, longitudinal shear resistance of 0.211 N/mm² was recorded for three slabs with a length of 1800mm while 0.328N/mm² was recorded for the fourth slab with 1300mm length. However, ultimate resistance was noted to be similar for both galvanized and ferritic stainless-steel composite slabs.

In summary, the Kathleen Lauwens and colleagues concluded that the concrete and stainless steel comprising the composite slab behaves as one structure and thus should be considered as one during design to maximize their properties and performance. In general, the resulting stainless-concrete composite slabs exhibit enhanced mechanical and corrosion resistance properties and thus will significantly advance their applications.