JohnCE920
Structural
- May 3, 2013
- 16
I am trying to resolve a difference in lateral steel reinforcement discrepancies between ACI 318-14 and AASHTO LRFB Bridge Design Spec 8th Edition regarding the volumetric reinforcement ratio in a column.
ACI 25.7.3 gives a volumetric ratio requirement for spiral lateral reinforcement. The purpose of the equation is stated to ensure that a fully realized core strength matches or exceeds that of the gross section when/if the cover spalls off. Makes sense. For column ties, outside of a min/max spacing, there is no equivalent section. Certainly no commentary to suggest that the min/max spacing of ties is intended to produce the same confinement mechanism as the spirals. Unless I'm missing something.
AASHTO has had a similar requirement for spirals in the past. But 8th edition just switched the section to include ties/hoops in the volumetric ratio check (Section 5.6.4.6). This is a major change in reinforcement requirements for non spiral reinforcements. Unfortunately AASHTO offers no commentary as to why the change was made.
Can anyone offer any insight to why or why not the volumetric ratio should be applied to ties/hoops? Thanks for any insight on this.
ACI 25.7.3 gives a volumetric ratio requirement for spiral lateral reinforcement. The purpose of the equation is stated to ensure that a fully realized core strength matches or exceeds that of the gross section when/if the cover spalls off. Makes sense. For column ties, outside of a min/max spacing, there is no equivalent section. Certainly no commentary to suggest that the min/max spacing of ties is intended to produce the same confinement mechanism as the spirals. Unless I'm missing something.
AASHTO has had a similar requirement for spirals in the past. But 8th edition just switched the section to include ties/hoops in the volumetric ratio check (Section 5.6.4.6). This is a major change in reinforcement requirements for non spiral reinforcements. Unfortunately AASHTO offers no commentary as to why the change was made.
Can anyone offer any insight to why or why not the volumetric ratio should be applied to ties/hoops? Thanks for any insight on this.
