Jeoku
Structural
- Feb 6, 2014
- 8
The AASHTO LRFD 2017 code is confusing me when it comes to designing concrete at supports and seems to contradict itself.
Section 5.5.1.2 "Design Methodologies" talks about needing to design B and D regions with different methods because of how the stresses goes through a beam at that location. D regions are those near supports and concentrated loads and B regions are everywhere else. They require D regions to now be designed with either strut and tie method and or some other special methods. This seems like it will complicate things a bit.
Where I am confused is that in the B region design paragraphs (5.7) there are requirements for shear at the supports such as paragraph 5.7.3.2 "Sections Near Supports" and 5.7.3.5 "Longitudinal Reinforcement". While the longitudinal reinforcement requirement could control away from the support, it makes me scratch my head because as you get away from the support you no longer have the shear coming in at an angle and producing tension in the reinforcement.
The bottom line is I am curious if I am missing something or is AASHTO being wishy-washy about the shear design in beams.
Section 5.5.1.2 "Design Methodologies" talks about needing to design B and D regions with different methods because of how the stresses goes through a beam at that location. D regions are those near supports and concentrated loads and B regions are everywhere else. They require D regions to now be designed with either strut and tie method and or some other special methods. This seems like it will complicate things a bit.
Where I am confused is that in the B region design paragraphs (5.7) there are requirements for shear at the supports such as paragraph 5.7.3.2 "Sections Near Supports" and 5.7.3.5 "Longitudinal Reinforcement". While the longitudinal reinforcement requirement could control away from the support, it makes me scratch my head because as you get away from the support you no longer have the shear coming in at an angle and producing tension in the reinforcement.
The bottom line is I am curious if I am missing something or is AASHTO being wishy-washy about the shear design in beams.
