Column for isolated frame

The purpose of the Column for Isolated Frame project is to perform buckling calculations of a concrete column as part of an isolated frame.

One of the factors which have influence on the buckling behavior of a column is the shape of the acting moments diagram. According to NEN-EN 1992-1-1 #5.8.8.2 the design moment value can be taken as sum of 1st and 2nd order moments. The original EN1992-1-1 formula is extended with the additional rule:

M_Ed=M_0Ed+M₂=Max(M_0e+M₂; M₂; M₀₁+0.5M₂)

In the user interface for internal forces definition input fields group "Loads" is created. One of these fields is for defining of the axial force value N_c;Ed. The value can be negative (compression) or positive (tension).

Bending moment values at the ends of a column (M₀₁; M₀₂), at the middle point of a column (Mmid) and the maximum value of the bending moment (M_yMax; M_zMax) can be provided for both buckling axes Y and Z:

Loads of a column for an isolated frame:

If the value of M_y(z)Max will be zero, M_0e will be calculated according to the equation (5.32) depending on provided M_y(z)01 and M_y(z)02 values and for the nominal 2nd order moment calculations will be used factor c = 8.

If the end moments M_y(z)01 and M_y(z)02 values will be set to zero, the 1st order moment M_0Ed will be equal to the value provided for the maximum bending moment M_y(z)Max and for the nominal 2nd order moment calculations will be used factor c = 9,6.

For the other cases the 1st order moment M_0Ed will be set to a maximum from M_y(z)02 and M_y(z)Max and for nominal 2nd order moment calculations will be used factor c = π².

The nominal second order moment is calculated according to the formula (5.33).