Design parameters for shear (Concrete wall: EC2)
For some of the shear design parameters, additional user defined limits can be applied - where this is the case minimum and maximum values are specified in Design Options > Column > Reinforcement Layout.
Minimum Shear Link Diameter
φw,min = MAX[ 6mm, 0.25 * largest longitudinal bar diameter ]
Maximum Span Region Shear Link Spacing
For design to UK NA, Irish NA, Malaysian NA and Singapore NA: 1
φw,max = MIN[ 20 * smallest longitudinal bar diameter, lesser column dimension, 400mm ]
For UK NA when concrete class > C50/60 there are separate calculations in clause 9.5.3(3). These are not implemented but a warning is displayed in this situation.
For design to EC2 Recommendations:
φw,max = MIN[ 20 * smallest longitudinal bar diameter, lesser column dimension, 400mm ]
Support Region Shear Link Spacing
For support regions, the maximum link spacing is reduced by 40%. 2
Long Term Compressive Strength Factor for Shear, αccw
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA: 3
αccw = 1.0
Design Concrete Compressive Strength for Shear, fcwd
For design to UK NA, Irish NA, Malaysian NA and Singapore NA:
fcwd = αccw * MIN (fck , 50) /γC
For design to EC2 Recommendations:
fcwd = αccw * fck /γC
Factor CRd,c4
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA:
CRd,c = 0.18 / γC
Factor k15
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA:
k1 = 0.15
Cracked Concrete Reduction Factor, v
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA: 6
v = 0.6 * (1 - (fck / 250))
Cracked Concrete Reduction Factor, v1
For design to UK NA, Irish NA, Malaysian NA and Singapore NA: 7
v1 = v* (1 - (0.5 * cos(α))
α is the inclination of links.
Note that links in columns are always assumed to be at 90° to column direction.
Therefore v1 = v
For design to EC2 Recommendations:
v1 = v
Minimum Shear Reinforcement Ratio, ρw,min
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA: 8
0.08 * √(fck) / fyk
Maximum Angle of Compression Strut, θmax
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA: 9
cot(θ) = 1
θ = 45°
Minimum Angle of Compression Strut, θmin
For design to10 EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA:
cot(θ) = 2.5
θ = 21.8°
Angle of Compression Strut, θ
For design to UK NA, Irish NA, Malaysian NA and Singapore NA: 11
If NEd ≥ 0 i.e. compression
θ = 0.5 * arcsin(2 * vEd / (0.9 * αcw * v1 * fcwd))
else
cot(θ) = 1.25
θ = 38.7°
For design toEC2 Recommendations:
θ = 0.5 * arcsin(2 * vEd / (0.9 * αcw * v1 * fcwd))
Stress State Factor, αcw
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA:
If σcp ≤ 0
αcw = 1.0
else if 0 < σcp ≤ 0.25 * fcd
αcw = 1.0 + (σcp / fcd)
else if 0.25 * fcd < σcp ≤ 0.5 * fcd
αcw = 1.25
else if 0.5 * fcd < σcp ≤ fcd
αcw = 2.5 * (1.0 - (σcp / fcd))
Minimum Shear Strength , vmin
For design to EC2 Recommendations, UK NA, Irish NA, Malaysian NA and Singapore NA: 12
035 * k1.5 * fck0.5