Additional Longitudinal Steel (LRFD 5.8.3.5) in Concrete Bents

[TypeIV]

AASHTO LRFD's Longitudinal Steel Check (LRFD 5.8.3.5)requires additional longitudinal reinforcement due to shear. I have seen conflicting information regarding the requirement for this additional steel (Al) in a concrete bent/pier frame cap.

2007 AASHTO LRFD 5.8.3.5 states: "The area of longitudinal reinforcement on the flexural tension side of the member need not exceed the area required to resist the maximum moment acting alone. This provision applies where the reaction force or the load introduces direct compression into the flexural
compression face of the member."

I typically design concrete bents/piers that are just concrete frames that I think have this "direct compression" at each column. Do I need this additional longitudinal reinforcement for shear? This requirement is typically around 3 si to 6 si additional steel top and bottom and is really ridiculous.

 

[civilperson]

Add to just the compressive side, the tension steel due to flexure is sufficient on the other side.

 

[yakpol]

Shear analysis will stipulate how soon you can cut your tensile reinforcement. ACI does it by verbal requirements (don't cut if shear force is more than 2/3 of Vmax), LRFD puts equations in place. Maximum reinforcement is governed by bending at the face of the support (no shear check here).