An experimental study on double steel-concrete composite beam specimens

Double steel-concrete composite continuous beam is a new structural system, in which, there is a concrete bottom slab connected with the bottom steel flange through studs where the cross-section suffers negative moment. Three pieces of 2 x 2.9 m span double steel-concrete composite continuous beam specimens with full shear connection are designed and tested, and are subjected to concentrated loads and their self-weight in order to reveal the mechanical behavior of the composite beam in the paper. If once the concrete cracks, the interface flip occurs and then increases with the load because the used stud is a kind of flexible shear connector. The load-deflection curve, the ultimate flexural capacity, the interface slips and the slip strain between steel and concrete along the span direction are measured and obtained. The bearing capacities of the beam's cross-section by the tests are fairly close to the plastic moment by the simplified calculating formulae. Both the bending stiffness and the structural ultimate bearing capacity of the double steel-concrete composite continuous beam are greatly higher than that of the single steel-concrete composite continuous beam.