Design for bending for rectangular sections (beams and slabs: EC2)
| K |
|
MEd/(fck*bw*d2) |
| K' |
|
(2*η*αcc /γC)*(1 - λ*(δ - k1)/(2*k2))*( λ*(δ - k1)/(2*k2)) for fck ≤ 50 N/mm2 |
| K' |
|
(2*η*αcc /γC)*(1 - λ*(δ - k3)/(2*k4))*( λ*(δ - k3)/(2*k4)) for fck > 50 N/mm2 |
|
where |
||
| ki |
|
moment redistribution factors |
| δ |
|
moment redistribution ratio ( = 1.0 in the current release) |
| γC |
|
the NDP partial safety factor for concrete |
| αcc |
|
coefficient to take account of long term effects on compressive strength of concrete |
| λ |
|
0.8 for fck ≤ 50 N/mm2 |
|
0.8 - (fck-50)/400 for 50 < fck ≤ 90 N/mm2 | |
| η |
|
1.0 for fck ≤ 50 N/mm |
|
1.0 - (fck-50)/200 for 50 < fck ≤ 90 N/mm2 | |
| γC |
|
1.5 |
| αcc |
|
0.85 |
| γC |
|
1.5 |
| αcc |
|
1.0 |
IF K ≤ K' THEN compression reinforcement is not required.
Calculate the lever arm, z from;
| z |
|
MIN(0.5*d*[1 + (1 - 2*K/(η*αcc/γC))0.5], 0.95*d) |
| Ast,reqd |
|
MEd/(fyd*z) |
| where | ||
| fyd |
|
fyk/γS |
| γS |
|
the NDP partial safety factor for reinforcement |
| xu |
|
2*(d-z)/λ |
| γS |
|
1.15 |
IF K > K' THEN compression reinforcement is required.
Calculate the depth to the neutral axis from;
| xu |
|
d*(δ-k1)/k2 for fck ≤ 50 N/mm2 |
| xu |
|
d*(δ-k3)/k4 for fck > 50 N/mm2 |
| fsc |
|
MIN(Es*εcu3*(1-(d2/xu), fyd) |
| where | ||
| d2 |
|
the distance from the extreme fibre in compression to the c of g of the compression reinforcement |
| M' |
|
K'*fck*bw*d2 |
| z |
|
0.5*d*[1 + (1 - 2*K'/(η*αcc/γC))0.5] |
| As2,reqd |
|
(MEd-M')/(fsc*(d-d2)) |
| Ast,reqd |
|
M'/(fyd*z) + As2,reqd*fsc/fyd |