A composite beam is formed by a reinforced (possibly prestressed) concrete slab attached to the upper flange of a hot-rolled or welded steel beam by shear connectors so that the two components act together as a single section. As with steel beams, composite beams must be checked for both ultimate limit state and serviceability limit state. This lecture covers the principal checks to be applied to simply supported beams. This includes calculation procedures for the moment resistance, which depend on the section classification and position of the neutral axis. The treatment of elastic moment resistance depends on the construction sequence and whether the building is intended mainly for storage, in which case the loading is predominantly long term. Design checks for vertical shear are similar to those for bare steel beams. The design of the connectors is discussed in relation full and partial interaction, and the requirements for transverse reinforcement are described. Serviceability design is based on elastic analysis and concerns limiting deflections and controlling cracking in the concrete. The calculation procedures for these are outlined.
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