Precast column design
Specific aspects of the precast column design workflow in Tekla Structural Designer are described below:
Whist a variety of different section shapes can be defined in Tekla Structural Designer, the Tekla Tedds calculation only supports the design of rectangular and circular column sections.
While you can apply both normal and lightweight concrete in the column properties, column design using lightweight concrete is currently beyond scope.
The default nominal cover value set in Design Settings> Precast> Column> Reinforcement Settings is automatically passed through to the Tekla Tedds calculation. The nominal concrete cover is the distance between the surface of the reinforcement closest to the concrete surface (including links and surface reinforcement where relevant) and the nearest concrete surface.
Default reinforcement in the Tekla Tedds calculation
Regardless of the column size imported from Tekla Structural Designer, the initial default reinforcement for all stacks in the Tekla Tedds calculation is as follows:
- Rectangular columns: a 2x3 formation of 25mm dia rebars with 8mm shear links.
- Circular columns: 6x 25mm dia rebars with 8mm shear links.
The maximum number of bars which can be entered in either direction for rectangular columns is 10. For circular columns, the maximum total number of bars is 20. Please note that these restrictions will have an effect on the maximum allowable column size for the design workflow.
There is a basic minimum distance calculation within the Tekla Tedds document relating to bar amounts to avoid unrealistic values of rebar from being selected. This amount is to be the minimum of:
- K1 x bar dia
- k2 x max aggregate size
The number of link legs shown in the Tekla Tedds calculation will increase or decrease depending on the number of reinforcing bars assigned within the document.
Lifting Checks and Splice Design
Lifting checks and splice checks are disabled by default. This has been done to ensure a rapid design of grouped columns can take place. If these checks are required then simply enable the switches within the Design Options dialog within the Tekla Tedds calculation.
Analysis forces transferred from Tekla Structural Designer
The following values in the Tekla Tedds calculation are populated from the Tekla Structural Designer model.
- Axial load, 1st case (Max value)
- Axial load, 2nd case (Min value)
- Where tension exists in the column, the lowest compression value is populated into this parameter and the tension value ignored. A warning will be displayed in the process log within Tekla Structural Designer.
- Moment about y axis at top
- Moment about z axis at top
- Moment about y axis at bottom
- Moment about z axis at bottom
Other precast column properties
The following properties which are common to both cast-in-place and precast columns, are not transferred to the Tekla Tedds calculation, but require consideration as they impact the overall performance of the model.