Depth, Dc (mm) [Larger Cross-Section Dimension]:
Width, Bc (mm) [Smaller Cross-Section Dimension]:
Concrete Clear Cover (c):	25 mm 20 mm 30 mm 35 mm 40 mm 45 mm 50 mm
Characteristic Compressive Strength (f'c):	40 MPa 32 MPa 50 MPa 65 MPa 80 MPa
Number of Vertical Reinforcement along Width (nb):	Default 2 3 4 5
Diameter of Vertical Reinforcements (dv):	24 mm 16 mm 20 mm 28 mm 32 mm 36 mm
Diameter of Stirrups (ds):	12 mm 10 mm 16 mm 20 mm
Vertical Reinforcement Ratio (Pv ≥ 0.01):
Design Axial Force (N*) in kN:
Design Moment (M*) in kNm (at least 0.05N*xDc):
Moment Magnifier to include Slenderness (𝛿b):
Clear Length of the Column, Lu (mm):

Get Confinement Design

Figure 1. Diagram of design moment vs design axial load of the column.

2. Results
I. Confinement Design
The confinement demand (f_r,demand), and capacity or effective confining pressure (f_r.eff) are determined from Equation 1 and Equations 2-6, respectively, following Cl.10.7.3 of AS3600:2018. The confinement parameters used in these equations are shown in Figure 2. The stirrups spacing in the special confinement region is determined as follows:
a). For Lu > 5D, spacing = min [0.6b, 15dv, 300, spacing corresponding to f_r,demand ≥ 0.01f'c];
b). For Lu ≤ 5D, spacing = min [0.5b, 8dv, 24ds, 300, spacing corresponding to f_r,demand ≥ 0.01f'c].
Where, 'Lu' is the unsupported/clear length of the column; and 'D' is the overall depth of the cross-section in the plane of bending.
Where,
'k_e' is an effectiveness factors accounting for the arrangement of the fitments,
'f_r' is an average confining pressure on the core cross-section taken at the level of the fitments,
'b_c' and 'd_c' are core dimension measured between the centre-lines of the outermost fitments,
'A_b.fit' is the cross-sectional area of one leg of the fitment,
'n' is the number of laterally restrained longitudinal bars,
'n_b' and 'n_d' are the number of fitment legs crossing each confinement plane,
'w' is average clear spacing between adjacent restrained longitudinal bars,
'f_r.eff' is the effective confining pressure.

Figure 3. Cross-section of the column showing details of the vertical reinforcements and stirrups.

Table 2: Comparison of the confinement capacity (optimal solution) and demand (0.01f'c).

II. Length of confinement/critical region: $$ {l_{cr} = max(1.2D, L_{cl}/6})\tag{7}$$ The largest cross-sectional dimension of the column 'h_c', and the clear length of the column 'l_cl' are defined in the input section.
3. References:

1. Standards Australia (2018). AS 3600:2018 Concrete structures.

Disclaimer: "The authors assume no responsibility for any injury, damage, liability, negligence and/or otherwise to any individual or property from the use or application of any of the methods, products, instructions, or ideas contained in the material herein."