In the Behavior column, if the Creep and Preload tickboxes are ticked they will apply the worst permanent deformations from creep or / and preload simulations.

If Creep has been selected for an environment, then that environment will be simulated in FEA with the creep permanent deformation, if Preload is selected, then that environment will be simulated with the worst permanent deformation arising from simulations marked with Is Load in the simulation tab. If both Creep and Preload are selected, then the worst permanent deformation from either the preload or creep simulation is passed into the analysis.

If an environment is marked as post creep or post load, it cannot be the pre load environment or the creep environment

To calculate the creep deformation, the environment in which the creep deformation is calculated must be specified. To do so, open the design settings by clicking Project > Design Settings and select the required environment from the dropdown menu in the Creep Environment row.

Only environments with no wind can be selected, if an environment has wind specified it will not be shown in the dropdown.

The creep environment defaults to “None” meaning that no creep will be calculated for strain sections that have Creep from Library Definition as their creep model.

If there is a strain section with Creep from Library Definition as its creep model and the creep environment is not “None,” this discrepancy will be outlined in both the Design Settings and the Strain Sections Property Panel.

Once the creep strain is calculated from the selected environment, it will be applied to a strain section in the subsequent simulations of environments that have the Creep tick box ticked.

Neara currently supports three creep models for strain sections:

This is the default behaviour, creep permanent deformation of material is zero and in post creep simulations the material's stress strain curve is the library defined 1 hour curve.

Creep permanent deformation is calculated as the multiple of material thermal expansion coefficient and user specified temperature. In the case when Design Settings define a creep environment then the simulation is run using the permanent deformation from this environment at the beginning of the simulation. This can result in different permanent strain being propagated to post creep simulations in the cases where end of the creep simulation stresses in material are larger than the stresses leading to initial permanent deformation. In the case when the creep environment is set to “None” then the permanent deformation is passed as is.

If the creep model of strain section is changed to another model, then the user specified thermal offset will default to zero, even if it was previously specified as non zero value, effectively disregarding creep from constant thermal offset.

This option will use the ten year creep polynomial defined in the Conductor library to calculate the creep. In the creep environment, cable deformation at the end of the simulation will be calculated from the aforementioned ten year stress strain curve. After which the cable will be unloaded via final modulus line yielding creep permanent deformation read as the difference between the point where final the modulus line intersects X axis and root of stress strain polynomial.

In the case when ten year creep curve is poorly defined the user will be notified.

In Strain Section Properties under the Catenary Definition section the cable constraints in after creep conditions at a given temperature (usually survey temperature) can be defined.

From those after creep conditions, FEA will run back calculations to determine stringing conditions which are then starting conditions for all simulations.

Results of cable forces and shapes in stringing or after creep conditions can be easily accessed from reports no matter what the constraining conditions are. Selecting the constraint to be “final after creep” will not automatically apply creep to simulations.

To do so, follow the steps outlined in Creep Models for Strain Sections above.