Beam-column joint shear strength (ACI 318-19 update)
Summary
When working to the 2019 version of the code the Concrete column and wall design to ACI 318 checks are amended as follows:
-
As per clause 15.4 added joint shear strength check for gravity load conditions in line with the seismic design.
Joint shear strength check
-
A new node of “Joint Shear Strength“ is added to the column design results tree under Shear Links
-
The strength reduction factor φ is taken as 0.75
-
Overstrength factor, η taken as 1.0
-
Probable moment strength is changed to nominal moment strength
Note: Beam nominal strength is based on the rectangular section and slab
reinforcement is not considered.
The γ factor used in computing the joint shear strength is adjusted as per table 15.4.2.3,
| Column | Beam in the direction of Vu | Confinement (Consider Transverse Beam) | γ |
|---|---|---|---|
| Column is continuous at joint (b) AND length of stack above ≥ column depth in direction of shear (a) | Beam is continuous at joint AND length of beam on both sides ≥ beam depth | Transverse Beams covering more than or equal than ¾ of the column face and Length of transverse beam ≥ transverse Beam Depth | 2.0 (24) |
| Transverse Beams not covering more than or equal than ¾ of the column face OR Length of transverse beam < transverse Beam Depth | 1.7 (20) | ||
| Beam is not continuous at joint OR length of beam on either side < beam depth | Transverse Beams covering more than or equal than ¾ of the column face and Length of transverse beam ≥ transverse Beam Depth | 1.7 (20) | |
| Transverse Beams not covering more than or equal than ¾ of the column faceOR Length of transverse beam < transverse Beam Depth | 1.3 (15) | ||
| Column is not continuous at joint (b) OR length of stack above < column depth in direction of shear (a) | Beam is continuous at joint AND length of beam on both sides ≥ beam depth | Transverse Beams covering more than or equal than ¾ of the column face and Length of transverse beam ≥ transverse Beam Depth | 1.7 (20) |
| Transverse Beams not covering more than or equal than ¾ of the column face OR Length of transverse beam < transverse Beam Depth | 1.3 (15) | ||
| Beam is not continuous at joint OR length of beam on either side < beam depth | Transverse Beams covering more than or equal than ¾ of the column face, and Length of transverse beam ≥ transverse Beam Depth | 1.3 (15) | |
| Transverse Beams not covering more than or equal than ¾ of the column face OR Length of transverse beam < transverse Beam Depth | 1.0 (12) |