Can someone please explain the exact mechanics of development of bearing stresses in concrete on account of bending of steel reinforcement and/or providing of hooks at the beam-column junction for anchorage? Would there be no bearing stresses if the rebars are not bent at the said location? In other words are the bearing stresses a direct consequence of bending the rebar or introduction of hook?
Hooks are used in many situations in RC. They are used for example in column beam intersection to give ductility and confinement of the joint in case of an earthquake. They are used in beams and columns for transition or when there is not enough bonding strength length available, by developing tension in confined areas, or they are used at the end of the beams to wrap the beam with steel. Hoe ever they are not principally used for bearing strength!
They do this by
Taking advantage of extra embedment to fully develop tension in the bar.
By adding tension by mechanical properties of the rebar resisting unwinding and concrete's compressive stress working on the corners of the bar.