Design (Concrete Section)

Last modified by Fredrik Lagerström on 2021/08/06 14:46

When Design has been activated a design of one or more loadcases in Ultimate Limit State can be performed. Loadcases in Serviceability Limit State can be defined but will be ignored during the calculation. A calculation of these will be performed when Analysis is activated.

The Input data field

The input data field contains a number of tabs where the example is being defined. The field contains initially the tabs Section information and Section and Load case.

Section information

In the Section information dialog the current cross-section is defined by using the Section database.


The Section database contains the option Standard Eurocode concrete and Non-standard concrete.

  • Standard Eurocode concrete

    Standard Eurocode concrete consists of eight geometries where a number of pre-selected sections has been added.


  • Non-standard concrete
    Non standard concrete consists of eight pre-selected geometries for which a name and the dimensions are to be given by the user. When the section has been defined it will be put in the Section name list where it will be available for the current program installation.




New sections are stated by the Add button, removed from the list with the Delete button and are opened for changes with the Change button.


In the loadcase dialog box current section forces as well as limit state and type are defined. In program mode Design only loadcases in the Ultimate Limit State can be calculated. Loadcases in the Serviceability Limit State can also be defined but these will be ignored during the calculation. For Ultimate loadcases also the type Accidental can be stated.


When a loadcase has been defined the active section, as well as other active input data, will be tied to it. When one or several loadcases have been stated the currently active loadcase will be stated in the status bar at the top of the program window. All input data and results belong to the active loadcase. Thus selecting another loadcase in the table also changes section data. This means that sets of section forces simultaneously can be calculated with several different sections. A cross-section can, as an alternative, at a simultaneously calculation be designed for an arbitrary number of section force sets.


The input is made easier by load-directions that are shown for the section of the active loadcase on the drawing area.

Loadcases can be edited in several ways using Add, Copy, Create new, Change and Delete.

By pressing the Add button a new loadcase is added to the table provided that a new loadcase name (and forces) has been stated in the input field. The new loadcase will copy the current active section using default material and no bars or stirrups.

By pressing Copy button a new dialog window is opened in which it is possible to select from which section/loadcase data shall be copied.


By pressing Create new button a new dialog window is opened which include the copy function with possibility to change section.

By pressing Change button section forces in the selected loadcase are changed.

By pressing Delete button all data in the selected loadcase is deleted.

Load cases can also be linked to eachother by pressing the Link loadcases button.

When the section and the load cases have been defined the input data field is
completed with the tabs: Material, Reinforcement details and Calculation
settings. If one or more long time load cases are defined then also the tab Loadcase
dependent parameters is shown.



In the material dialog box all material strength input is assembled. By pressing one of the buttons [...] a dialog box for showing the complete data of the selected material or for defining a user defined material is opened.



Under the header General, conditions that affect the calculation are stated. Exposure class and life time class are defined and affect code checks where relevant. The options Quality control and reduced deviation and Reduced or measured geometrical data can be checked. The to latter options together with the option Low strength variation, see below, changes the partial factors for materials according to EN 1992-1-1 Annex A A2.1 and A2.2.


Concrete strength class can be defined by selecting from the list. Current design values are shown. If the option Low strength variation is checked together with one or both of the two options described above the partial factor for concrete will be changed according to EN 1992-1-1 Annex A A2.1 and A2.2.


By pressing button [...] beside strength class the complete current data is being shown, as is a graphic presentation of the stress-strain diagram. The values in the material data are available for changes when the option Create new is chosen.


In the Reinforcement dialog boxes type of reinforcement for bottom- and top bars and stirrups as well as for longitudinal bars can be defined by selecting from lists. Longitudinal bars are only used in the program Concrete Section to resist torsion and biaxial shear. Current design values as well as current diameters are shown.

By pressing button [...] beside strength class the complete current data is shown, as is a graphic presentation of the stress-strain diagram. The values in the material data are available for changes when the option Create new is chosen.

92848_-_denmark_flag.png Danish Annex

In the Danish Annex environmental classes are defined instead of exposure classes. The relations between these are the following:


For the Danish Annex also the Inspection Level should be defined which affects the partial factor for materials.


If the option Prefabricated elements is checked the partial factors for material is changed.

The options Reduced or measured geometrical data and Low strength variation are not used in the Danish Annex.

92865 - finland flag.png Finnish Annex

For the Finnish Annex also the Construction class are defined which affects the required cover.

92874_-_britain_flag_great.png British Annex

For the British Annex also the W/c ratio is defined depending on current exposure class. This option affects the required cover according to Table NA.2 and NA.3 in the British Annex.

Reinforcement details

In the Reinforcement details dialog box bar diameters, cover of reinforcement, min spacing between bars and so on used to distribute calculated amounts of reinforcement can be defined.


Main bar details

The diameter for bottom and top reinforcement are defined. If standard reinforcement is chosen the diameters are the ones available for that type. For non-standard reinforcement the available diameters are 1-99 mm.

Further on the covers at bottom, top and side are defined together with allowed distances between bars in the same layer and for different layers.

How the reinforcement is positioned is also influenced by the options Vibration space and Largest aggregate size.

The option Cover deviation represents the part of the total cover called Δcdev according to EN 1992-1-1

The option Use regular spacing in layer places the reinforcement evenly in the section instead of concentrated at the edges.

The program will choose minimum values (displayed with blue print) for the current diameter and code with the Code value button.

When the Code control option of input data has been activated the chosen values will be controlled, and compared with, existing rules for the current code.

Stirrup details

The user can chose to calculate completely without stirrups and will then get a warning if the shear capacity is not adequate. The calculation will then be performed according to EN 1992-1-1 6.2.2.

If stirrups are used the diameter is chosen, the angle between stirrup and beam axis and the minimum allowed distance between the stirrups.

Calculation settings

In the Calculation settings dialog different options governing the calculation can be set.


Shear calculation settings

Cot θ is defined where θ is the angle between the concrete compression strut and the beam axis.

The value affects the amount of required shear reinforcement according to EN 1992-1-1 6.2.3 and

1,0 ≤ cot θ ≤ 2,5

The user can choose between shear calculation with shear reinforcement according to EN 1992-1-1 6.2.3 and without shear reinforcement where this is allowed according to EN 1992-1-1 6.2.2.

2nd order moment calculation

This option is not used in the program Concrete Section.

Design settings

The user can define if compression reinforcement, if needed should be used or not.

The user can define if minimum bending reinforcement according to EN 1992-1-1 or should be considered.

Concrete section iteration settings

Input for the iterative section calculation can here be adjusted if needed.

SLS settings

The user can chose between two different crack criteria’s in the Serviceability Limit State.


According to EC2 7.1 (2) the value of the concrete tensile strength fct,eff may be taken as fctm or fctm,fl.

Normally fctm is used. fctm,fl is the criteria that normally result in the highest tension capacity and may be used for pure flexural stress. If tensile stresses, also those caused by shrinkage or thermal effects is present fctm should be used. As default fctm is used.

92997_-_flag_sweden.png Swedish annex


For the Swedish annex 7.3.2.(4) a third crack criterion can be used.

fct,eff = fctk / ζ

where ζ is a safety factor for cracking which depends on environment and age of structure table D-3.

Some guidance about which criteria is to be used will be displayed by pressing the info button and can be found in “Svenska Betongföreningens handbok till Eurokod 2” Volym I ch. 7.1.

Loadcase dependent parameters

In the Loadcase dependent parameters dialog box creep coefficients and shrinkage parameters for long time loads in Serviceability Limit State are defined. See the Analysis program mode.