The dialog is used to define parameters of timber member for the EN 1995-1:2004/A2:2014 code. It is available by selecting the New member type option in the Member Type dialog box or by pressing the Parameters button in the Definition dialog box.
The Member type field displays a name of a selected member type (you can enter any name of the member type to this field). Use the Buckling (Y axis) or (Z axis) fields to specify the length of a member for the appropriate plane. There are two ways to define this length:
- after selecting the Real option, a value you entered is interpreted as the member length
- after selecting the Multiplier option, a value you entered is interpreted as a coefficient by which to multiply the real member length to obtain the required value. E.g. entering the value of 0.25 means that the appropriate length equals ¼ of the real length.
The second way is very convenient to define simultaneously several members whose real lengths differ, while additional supports, for example, are equally spaced. If you want to save the set parameters as a category, you must define the length this way. If the value 1.0 is entered, it guarantees that the actual length will be adopted for each member defined as Ly using the category.
Member buckling length coefficients in both directions are defined in the Buckling Length Coefficient field. The actual member length (or the sum of the component member lengths) is automatically entered in the appropriate fields.
The buckling length coefficient depends on the end-support conditions of the member nodes in the buckling plane. The member buckling length may also be defined in the Buckling diagrams dialog, opened by pressing the icon representing a selected type of the member buckling model. Some typical diagrams of timber member support defined by the code can be found there; after selecting one of them, the coefficient value will be assumed or calculated automatically. Buckling is considered in calculations always when a compression force appears in the member, even if it is negligible in comparison to other internal forces. The program does not perform on its own a separate analysis that would determine if buckling effects may be disregarded or not. If the user wants to eliminate buckling effects from the calculations, the last icon in the Buckling diagrams dialog has to be chosen. If pressed, buckling will be disregarded in the calculation process.
The Lateral Buckling Parameters field allows selecting options used during verification of lateral buckling of the member: lateral buckling type, load level and lateral buckling length coefficient. Pressing the relevant icon opens the dialog box for definition of appropriate parameters.
The Lateral buckling type option allows defining appropriate code parameters of lateral buckling depending on the static scheme of a member. As determined by the code requirements, one of the schemes taken in consideration in the code should be adopted. The schemes in form of icons reflect precisely the appropriate code positions. Clicking the last icon means the user gives up considering the lateral buckling effects in calculations.
To perform lateral buckling calculations you need to specify the distance between cross-sections protected against torsion for a member, that is the lateral buckling length. You can distinguish 2 lateral buckling lengths because the upper or lower flange can be fixed separately and the compressive stress may occur in the upper or lower flange for different load cases. The dialog displays values of the coefficient by which to multiply the base member length to obtain the lateral buckling length. The length Iz is taken as the base length. It is possible to enter the coefficient value directly or select the icon representing a typical fixing case for which the coefficient will be automatically chosen.
If the Double sections treated as solid option is activated, the double section in duration of the lateral buckling analysis is treated as solid.
The options which can be found in the Method of critical stress determination allow to select the calculation method of the critical stress in lateral buckling. According to the code, it is possible to use two formulas for the critical stress determination in lateral buckling:
- critical mass (code article 6.31)
- detailed formula for soft timber (code article 6.32).
The selection list of the service class, which depends on the material humidity and the relative air humidity service class, is available as well in the bottom part of the dialog.
Pressing the More button opens an additional dialog box for definition of the remaining member type parameters provided in the code such as: load type, section parameters, etc.
Click the Service button to open an additional dialog to define member type parameters (limit displacements, initial deflections).
Pressing the Others button opens an additional dialog box for defining parameters of the fire resistance of a member.
Pressing the Fire button opens an additional dialog box for defining parameters of the fire resistance of a member.
Pressing the Add button adds the member type with the defined name and parameters to the list of previously defined timber member types.