COMPOSITE PROFILED BEAMS

It is now common practice to use cold-formed steel decks consisting of profiled sheets both as permanent formwork for the support of the soffits of reinforced concrete slabs and also as part of the tension steel in the composite profiled slab that is formed after the concrete has hardened. The behavior of steel profiled sheets as permanent formwork to the sides of reinforced concrete beams is described in this paper. Experimental tests on large-scale beams show that the addition of profiled steel sheets to the sides of reinforced concrete beams can substantially increase both their flexural and shear strengths without loss of ductility and that this system is not prone to shear bond failure at the profiled-sheet/concrete-beam interface. Furthermore, theoretical studies suggest that the addition of side profiled sheets will substantially reduce long-term deflections due to creep and shrinkage of the concrete and allow increases in the span/depth ratio of about 20%.