Partial fixity of column bases

Tekla Structural Designer
2021
Tekla Structural Designer

Partial fixity of column bases

Two additional types of rotational linear spring are provided to allow partial fixity to be modelled, these are:

  • Nominally pinned
  • Nominally fixed

These are specifically provided for supports under columns (of any material), but will result in a validation error if placed under walls, or if they are used for any other supports.

The support stiffness is based on the column properties (E*I/L)

  • E = Young’s Modulus of the column
  • I = relevant bending stiffness (Ixx or Iyy) of the column
  • L = distance from the support to the first column point (stack) that is on a Construction Level checked as a Floor in the Levels dialog, i.e. combined length of all the stacks until a floor is found.
Note: Where no Floor has been defined in the column above the support, then L is taken as total length of column.
Partial fixity spring stiffness is calculated as follows for each of the two bending releases Mx and My:
  • Nominally pinned (spring stiffness) - x% * 4 * E*I/L (default x% = 10%)
  • Nominally fixed (spring stiffness) - x% * 4 * E*I/L (default x% = 100%)

Since the spring stiffness is dependent upon stack height and column stiffness (E and I), the spring stiffness will change if any changes are made to column stack height, column E or I values.

In addition, since for steel, Auto Design can change the column size (and hence I value) the spring stiffness will change with any change in column size.

Czy to było pomocne?
Wstecz
Dalej