Concrete Pier Reinforcing 1

[haynewp]

I have seen many large embedded concrete pier foundations for billboard sign columns and transmission tower columns placed without any pier reinforcing.
I assume the area of steel of the column itself (which is embedded deep into the piers) is thought to provide the minimum steel requirement and also to transfer axial load through the pier so that no horizontal ties are required.
If the pier extends a few feet above ground, should there then be minimum vert. reinforcing around the pier perimeter to control minor cracks people may see (like light poles in parking lots)? Or is differential movement required for significant cracks, like a slab on grade???

 

[Ron]

haynewp...In my area, just about everything gets reinforced because of the significant moment at the top of the shaft due to wind loads. If the columns are indeed embedded deeply into the shaft or pier, then theoretically there might be no significant reinforcement issue; however, don't neglect the stress concentrations developed by embedded columns on the concrete. If a column has significant bending stresses, it imparts those to the concrete, even if the stiffness of that section is greatly increased.