Clause 12.3.1.2.3 (NEN 6770): Rotation/bending capacity

The Dutch NA also requires additional checks as per clause 12.3.1.2.3 of NEN 6770.

The checks given in this clause deals with additional checks for columns that form part of a buttressed or non-butressed framework.  The program uses the ESTIFF parameter with two different values to identify the framework type:

These checks are described below:

1. For columns in buttressed frameworks the buckling length is to be taken based on either

   • the system length or
   • the distance between adjacent lateral supports

   The following conditions should also be satisfied:

   If Nc;s;d/ Npl;d < 0.15, no additional checks are required

   If Nc;s;d/ Npl;d ≥ 0.15  and the steel grade is S235 or S 275 then

   $\frac{N_{c;s;d}}{N_{pl;d}}+\frac{{\lambda }_y}{120}\le 1$

   Where:

   • N_c;s;d is the axial load in the section
   • N_pl;d = Axial capacity of section = A·f_y;d
   • λ_y = Slenderness of the section about the major axis ( Y-axis)

   If Nc;s;d/ Npl;d ≥ 0.15  and the steel grade is S355 then

   $\frac{N_{c;s;d}}{N_{pl;d}}+\frac{{\lambda }_y}{100}\le 1$

   Where:

   • N_c;s;d = the axial load in the section
   • N_pl;d = Axial capacity of section = A·f_y;d
   • λ_y = Slenderness of the section about the major axis ( Y-axis)

2. For columns that are not part of buttressed frameworks the following additional checks need to be done:

   If Nc;s;d/ Npl;d < 0.15, no additional checks are required

   If Nc;s;d/ Npl;d ≥ 0.15  and the steel grade is S235 or S 275 then

   $\frac{N_{c;s;d}}{N_{pl;d}}+\frac{{\lambda }_y}{100}\le 1$

   Where:

   • N_c;s;d = the axial load in the section and
   • N_pl;d = Axial capacity of section = A·f_y;d
   • λ_y = Slenderness of the section about the major axis ( Y-axis)

   If Nc;s;d/ Npl;d ≥ 0.15  and the steel grade is S355 then

   $\frac{N_{c;s;d}}{N_{pl;d}}+\frac{{\lambda }_y}{80}\le 1$