Correct Answer - Option 1 : Interface slipping is prevented by using shear connector
(i) Shear connectors are utilized in composite structures to enable the combined action of the concrete slab and the steel profile. The shear connector was developed by Leonhardt to improve the fatigue strength of a Venezuelan composite bridge.
(ii) The shear connector is made from a rectangular steel plate, with holes, welded to the steel beam top flange.Interface slipping is prevented by using shear connector.
(iii) Shrinkage occurs when excess water evaporates out of the hardened concrete reducing the volume of concrete. By using same grade of concrete differential shrinkage cannot be avoided.
(iv) Assuming that there is no temporary propping, the steel part of a composite cross section must alone resist self-weight and other construction loads as the concrete at that stage is ineffective.So Precast member is not always designed to carry the weight of in-situ concrete without props.