Behaviour of concrete composite slabs with truss type shear connectors of different orientation angle

Concrete composite slab system with pre-cast bottom segment and cast-in-situ top segment is gaining importance due to wide-ranging applications in buildings, bridges and industrial flooring, etc. These slabs may also be subjected to repeated loading during its service life and hence, it is essential to evaluate their static and fatigue behaviour under flexural loading. In present study, at first, experimental investigations are conducted to evaluate the performance of composite slabs with truss type shear connectors with two orientation angles, namely, 45° and 60°. The composite slab specimens are subjected to four-point bending. The load-versus-displacement responses obtained for the composite slabs are compared with that of control full slab. It is observed that the composite slab with 45° shear connector showed better performance when compared to composite slab with 60° shear connector in terms of load-displacement response, rotation, ductility and energy absorption and also found to be efficient in terms of area of steel crossing the interface. Further, numerical investigations are also carried out to assess load transfer mechanism of truss type shear connectors at different significant events. The force flow mechanism of truss type shear connectors is brought out clearly. From the numerical investigations on composite slabs with different orientation angles, it is observed that composite slab with 45° shear connector exhibited superior performance over other orientation angles in terms of better force flow mechanism and lesser area of steel crossing the interface. Further, fatigue performance of composite slab with 45° shear connector is evaluated and compared with the fatigue performance of control slab. It could be observed that the composite slab with 45° truss type shear connector showed better fatigue performance when compared to the control slab.