Analysis Model settings

Tekla Structural Designer
2021
Tekla Structural Designer

Analysis Model settings

On the Analysis Model page you can adjust certain rigid zone, curved beam, and concrete column centerline settings:

Rigid Zones

Design codes allow engineers to assume parts of concrete beams or columns are rigid, leading to more efficient designs.

Note: Rigid zones should not be confused with rigid offsets, which are used to ensure that the analysis model is properly connected. You can have rigid offsets in the model even if rigid zones are turned off.
Item Description

Percentage of rigidity

Allows you to specify the extent of the rigid zone created. The option has an effect only if rigid zones are applied (see below).

Rigid zones not applied

Allows you to switch rigid zones on or off. The option affects where releases are applied in the analysis model and where members start and end for design.

When rigid zones are not applied, the design model corresponds to the analysis model, whereas when they are applied, the design model is defined between the ends of the rigid zones.

Note: There is a significant difference between Rigid zones not applied and rigid zones applied with 0% rigidity. The total elastic length of a member will be the same in the two models, but the position of releases and start or end of design members will be different.

Curved Beams

In the solver model, curved beams are replaced by a series of straight line solver elements. The number of solver elements used being controlled by the Maximum facet error that has been specified.

Item Description

Maximum facet error

For any given chord height, reducing this value increases the number of solver elements used to represent the curve.

Column Centerlines

For concrete columns connected to a two-way slab, the column perimeter shape is cut out of the slab 2D element mesh. Stiff analysis ‘rigid link’ elements then connect the column centerline (where the column 1D elements are located) to the 2D mesh nodes. In some circumstances - for example for L-section columns of certain proportions - very short link elements could result, which could cause validation errors or warnings and analysis solution problems.

The following settings are provided in order to move the column centerline a small distance where needed to avoid these problems.

Item Description

Automatically move column centerlines when the smallest rigid link is less than the error limit for 1D element length

This option is initially on by default.

The error limit used in this check is specified in Validation settings

Automatically move column centerlines when the smallest rigid link is less than the warning limit for 1D element length

This option is initially off by default.

The warning limit used in this check is specified in Validation settings

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