New Concept of Composite Steel-reinforced Concrete Floor Slab in the Light of Computational Model and Experimental Research

Abstract

This paper deals with a new concept of composite steel-reinforced concrete floor slab. This type of the floor slab consists of newly constructed steel and concrete composite beam mandatory connected together with cast in situ or prefabricated floor slab. The description of the nonlinear behavior of this newly designed steel and concrete composite beam with horizontal studs is a subject of a separate paper. Existing test results indicate that the loss of capacity of such structures may be linked to the loss of bonds between the composite beam and the floor slab. To prevent such behavior, special connecting elements have been designed in form of RC studs. Two types of structures, each consisting of composite beam and the prefabricated floor slabs, have been the subject of full scale tests performed in cooperation with ITB strength tests laboratory. Prefabricated prestressed hollow-core floor slabs have been supported on lower flanges of the steel part of the composite beam with reversed TT cross-section to provide a flat lower surface of finished floor slab. In order to prevent the separation of composite beam and floor slabs a number of reinforced concrete studs were arranged for ensuring the adequate bond between these components. The studs have been devised as the set of horizontal rebars passing through the perforated webs of the beam and anchored in the circular openings of the hollow-core slabs. Self-compacting concrete have been used to obtain adequate filling of hollow-core slabs openings. The studs have been designed according to the provisions of Eurocode 2. The expression defining the load carrying capacity of this junction, after some rearrangements, enabled the derivation of equations for the determination of the slab width interacting effectively with composite beam. As an interconnection between composite beam and slabs, these studs have sufficient strength and stiffness to enable both components of the structure to be designed as the parts of a single structural member able to attain the ultimate limit states. During the tests no signs of splitting between beam and slabs subjected to design loads were observed. Experimental and computational results showed satisfactory consistence.