Construction Stages#

The SSD task task_csm_small Construction Stages provides the definition and analysis of the construction process. It enables the computation of effects that come from changes in the structural system during the construction process, investigate time dependent effects like creep and shrinkage and calculate the prestressing.


Based on the defined construction sequence the Construction Stages task creates a set of loadcases, that are used to store the results of the analysis. For a detailed description of the created results and the scheme of the created loadcase numbers see the following page Construction Stages - Results.


Define the stages of the construction process.

Construction Stages - Stages

An individual stage should be defined for each event of the construction process, like for example

  • a change in the structural system (e.g. adding or removal of structural elements or changing of cross-sections)

  • the stressing or removal of tendons

  • the application of loads during the construction process (e.g. additional dead loads, loads related to formwork, etc.)

Stages must also be defined for the time intervals, where creep and shrinkage happens.


Changes in the cross-section of beams during the construction process (e.g. addition of in-situ concrete parts) can also be modeled. In these cases it is necessary to define the construction process for the cross-sections in the Cross-section editor or module AQUA.

Add construction stages by clicking on the plus_large button and set their properties:

Stage Number - the construction process is modeled as sequence of individual stages with ascending stage numbers. This number is used to identify the individual stage!


We recommend the following scheme for the numbering of the stages:

  • 10: activation of first group of elements

  • 11: prestressing

  • 12: grouting

  • 13: loads of construction stages (e.g. formwork)

  • 15: creep-step(s)

  • 20: activation of next group of elements

With this scheme additional stages can be added in between without restructuring the complete construction sequence.


At the bottom of the tab you can set an Offset for new stage numbers. Newly created stages are given the number of a selected stage plus this offset. You can still change the stage number after creation.

Title - is used as title for the loadcases created for this construction stage (to keep an overview over the construction process and the created loadcases).

Type - is the action that is assigned to the construction stage (resp. the related loadcase) and later used for the superpositioning for the design.

The following input is only available and relevant for stages for creep and shrinkage (Type C_1, C_2). The creep and shrinkage in this stage is calculated based on these settings.

Duration - set the length of the creep interval in days.

Relative humidity - set the relative humidity of the ambient environment.

Temperature - set the concrete temperature in the time interval.

Creep steps - the creep stage will be divided into the given number of steps. Additional stages are created based on the number of steps (with number = stage number + i; with i ranging from 0 till number of creep steps - 1).


In statically indeterminate systems creep and shrinkage generally lead to a change of the internal forces and the stress in the structure, which in turn affects the further development of creep. To deal with this topic SOFiSTiK follows the approach of dividing the creep stage in several creep steps. The creep of each step is calculated based on the stresses from the previous one. If the number of creep steps is increased the results will converge to the “real” solution, where the stress that causes the creep develops continuously with time.

Precamber analysis#

If precamber analysis is activated, elements are created with precamber so that the deflection in the selected Target construction stage is compensated by the precamber. The shape of the deflected system in the Target construction stage equals the shape of the system as defined within SOFiPLUS(-X) / SOFIMSHC or SOFIMSHA.


Define the properties of the structural elements and when they are activated.

This is done on the level of the primary groups of structural elements. Make sure to set the group definitions accordingly.


It is possible to assign construction stages to groups graphically in SOFiPLUS(-X). The assignments from SOFiPLUS(-X) will be used to create the initial setting for Stages and Groups in the task. You can still edit these settings according to your purpose and also reload the initial setting with the Init button. Decisive for the calculation are the settings from the Construction Stages task!

Construction Stages - Groups

Add groups by clicking on the plus_large button and set their properties:

Group Number - group that should be activated.

First Activation - construction stage when the group (resp. its stiffness) is first activated.

Active till - construction stage after which the group is removed (default: group active until infinite)

Concrete Age - age of the concrete at group activation (for the calculation of creep).

Hinges fixed at - construction stage when hinges are fixed (only for beam hinges, default: hinges are always active)

Bedding activated at - construction stage when the bedding of shell-elements is first activated

Situ concrete load from - set a construction stage for the activation of the dead load of cast in-situ concrete parts of cross-sections. (default: dead load of in-situ concrete is activated together with its stiffness)

Dead load from - construction stage when the dead load of the group is activated (default: dead load is activated together with stiffness resp. at First activation)

\(\mathbf{\Phi}\) springs - factor for creep of springs and beddings (default: 1.0 - springs creep)

FAC1 - factor for the stiffness of the group at first activation.

QUEA - factor to reduce the normal force stiffness component of shell elements

QEMX - factor to reduce the elastic modulus of shell elements in local x-direction


Construction Stages - Loads

Add plus_large loads from already defined loadcases (from SOFiPLUS(-X)/SOFILOAD) to be applied in the construction stages.

Loadcase - number of the loadcase

First Activation - set the construction where the load starts to act

Active till - set a construction stage after which the load should stop to act (per default the loads will act until infinity).

Factor - apply the loads with a factor.


  • Loads that are applied via the Construction Stages task should be defined in loadcases with action None in SOFiPLUS(-X)/SOFILOAD, otherwise they might be applied twice in the superpositioning.

  • The self-weight of the structure is applied automatically, if the corresponding option in the tab Control Parameters is used. In this case a definition of the dead load for the structural elements in the tab Loads is not necessary.

Control Parameters#

Set advanced control options for the calculation of the construction process. For a detailed description of these settings see also command description for CTRL in manual of module CSM.

Construction Stages - Control Parameters

Dead load activation

  • Automatic activation: the dead load of the structural elements is automatically applied based on the volume and self weight of the material

  • No activation: no automatic application, dead load has to be applied via self-defined loadcases in tab Loads

Module for creep & shrinkage - for further information see manual of module CSM, section 2.6

  • AQB (only for beam elements)

  • ASE (for beam and quad elements)

Creep and shrinkage for beam elements - for further information see manual of module CSM, section 2.6

  • Advanced creeping (depending on stress state)

  • Standard creeping

Use creep and shrinkage according - choose a theoretical model for the calculation of creep and shrinkage (default: the choice is made depending on the design code; for further information see also section 2.4 in manual of module AQB)

Tendon relaxation - de-/activate the relaxation of tendons

Formwork placement - choose in which position new elements are added to the system (for a detailed description see manual of module CSM, reference for command CTRL CANT)

Calculate cast-in-one loadcases for comparison - calculate additional loadcases with the assumption that all elements of the structure are cast in one stage (for comparison/checking purposes)

Stress results for all stages - de-/activate the calculation of linear elastic stresses for beams for each construction stage

Type of analysis - set the type of analysis:

  • Linear: Linear analysis (material and geometric)

  • Including nonlinear effects: treatment of springs with material nonlinear behavior, cables under pressure, nonlinear bedding; for material nonlinear behavior of shell and volume elements additionally activate Material nonlinearities (see below)

  • Full geometrical nonlinear analysis: geometrical nonlinear analysis (e.g. buckling, snap through, etc.); the features of the setting Including nonlinear effects are also available with this option

Material nonlinearities - de-/activate nonlinear material behavior for shell and volume elements (yielding of steel, cracking of concrete, etc.); for shell elements the minimum reinforcement defined in the task Design parameters of area elements) is always applied in the material nonlinear analysis; for additional settings see section Nonlinear Analysis for QUAD elements.

Stiffness evolution of young concrete - de-/activate the stiffness evolution of young concrete

Separation of GPC loads for construction stages: Removing temporary supports - de-/activate separation of actions G, P and C for systems with removal of temporary supports (for a detailed description see manual of module CSM, section 2.13.1)

Nonlinear Analysis for QUAD elements#

Set Reinforcement distributions and Additional settings for the nonlinear calculation of shell elements.

Use this reinforcement distribution number - set the reinforcement distribution to be used in the material nonlinear analysis from a previously calculated distribution (e.g. from a previous design based on construction stages with linear analysis)

Store calculated reinforcement in this distribution number - The reinforcement used in the material nonlinear analysis is stored under the given distribution number (in case the distribution given above is overwritten in a following design or if a factor is used on the amount of reinforcement).

Stiffness of beams - in general beam elements are calculated linear in a material nonlinear calculation for shell elements. With this setting you can specify a reduction factor for the beam stiffness for concrete beams (to approximately account for the stiffness reduction due to cracking).

Factor for reinforcement - factor for the applied reinforcement amount within the shell elements

Number of iterations - maximum number of iterations in the nonlinear analysis

Beam selection for check print#

Add and select beam elements for a check print of the internal forces, cross-section properties and resulting (linear elastic) stresses.


Use the animator_large button for a graphic selection of elements in the System visualization.

Construction Stages - Check Print

Text Output#

Specify the scope of the output (ranging from No output to Extensive output).

Construction Stages - Text Output