Longitudinal reinforcement is designed with the Simplified method from the French national application guide FD P18-717 of the norm EN1992-1-1. The simplified method should be applied if the following conditions are satisfied:
compression is centered
the slenderness λ is less than 120
20 MPa < f_{ck }< 50 MPa
h > 0.15, where h is the column’s dimension in the buckling direction
The formulas that should be used for calculation:
Rectangular section
N_{Rd} = k_{h} × k_{s} × α × [b × h × f_{cd} × A_{s} × f_{yd}]
Circular section
where:
b is the width of the column
D is the diameter of the circular section
h is the column’s dimension in buckling direction
L_{0} is the buckling length
For the calculation of d':
Because, in the design phase, the real d' is not known, the software will use in calculation the concrete cover from the Concrete covers dialog:
d' = 25 mm
Design Assumptions – Concrete cover
In the first stage, the calculation will be done using the value from the dialog and will result in a longitudinal reinforcement area and a transversal reinforcement area with certain diameters.
In the final stage, the calculation is done again with the real d' obtained as:
The report will contain the final stage calculation, with the real value of d'.
Note: If the values of δ and ρ are not known, it can be considered that (1 - 6 × ρ × δ) = 0.95. The Advance Design module considers a value for k_{h}=0.93.
With the Simplified method, the calculation is done on both planes, but the report keeps the results for the plan giving the maximum reinforcement area.