Reinforcement Mobilized and Visibility

[Pixy]

The stirrups of beam and midspan longitudinal bars of beam can only be mobilized once the concrete has cracks, and the hairline cracks can be visible.

1. But are there other concrete members where the reinforcements are mobilized yet there are no crack visibilities?

2. How about in masonry walls. Before the vertical rebars can be mobilized, are you supposed to see cracks in the walls. Or since the masonry units are like segments, then the cracks can be inside?

3. In columns for example where there are moments say bending to right. Before the tension or left part of the longitudinal bars are mobilized. Are you supposed to see the cracks in the column or does this occur inside without any visibilities?

Thanks.

 

[rowingengineer]

If the assumption is that concrete has no tensile capacity, then what you say is true. However concrete does have a tension capacity, so the Reo will take some force before cracks form even at the non visible level.