Additional reinforcement for torsion (concrete beam: EC2)
|
The design value of the shear resistance of a concrete section with no shear reinforcement, VRd,c is given by;1 |
||
| VRd,c |
|
νmin * bw * d |
|
||
| For design in accordance with EC2 Recommendations, UK NA, Irish NA, Malaysian NA, Singapore NA, Finnish NA and Swedish NA; | ||
| CRd,c |
|
0.18/γC |
| γC |
|
1.5 |
| vmin |
|
0.035*k1.5*fck0.5 |
| where | ||
|
k |
|
MIN(1 + √(200/d), 2.0) |
|
||
| For design in accordance with Norwegian NA; | ||
| CRd,c |
|
0.15/γC |
| γC |
|
1.5 |
| vmin |
|
0.035*k(2/3)*min(fck,65N/mm2)0.5 |
|
||
| where | ||
|
k |
|
MIN(1 + √(200/d), 2.0) |
|
||
|
If (ΤEd,max/ΤRd,c) + (VEd,max/VRd,c) ≤ 1.0 THEN no additional longitudinal reinforcement for torsion is required. IF (ΤEd,max/ΤRd,c) + (VEd,max/VRd,c) > 1.0 THEN additional longitudinal reinforcement for torsion, A slT,reqd is required in some or all regions. The additional longitudinal reinforcement is given by; |
||
| AslT,reqd |
|
(ΤEd * uk* cotθ)/(2 * Ak * fyd) |
|
where |
||
| uk |
|
2*((h-tef)+(bw-tef)) |
|
This reinforcement is in addition to that required for bending and tension arising from vertical shear and it is distributed in each of the four faces of the beam in proportion to the length of the face of the cross-section. The area of the additional link reinforcement that is required to resist torsion is given by; |
||
| Aswt/s |
|
(ΤEd)/(2 * Ak * 0.9 * fywd* cotθ) per leg |
Footnotes
1 The design
value of the shear resistance is calculated ignoring the
longitudinal reinforcement as it is not known if this
reinforcement is adequately anchored beyond the point under
consideration. This is a conservative approach.