Reinforcement design - 2D - Internal forces

The command displays design forces, which are in the program primarily calculated as part of the Reinforcement design (ULS+SLS) procedure. However, the design forces are also applicable as standalone input for a manual design if necessary.

In general, the design of the 2D reinforcement meshes - prescribed at the upper/lower surface of 2D members - requires recalculation of the internal forces into the directions of the reinforcement layers (defined in the Design defaults) to enable in each direction run common uniaxial design. As a transformation procedure, the Baumann method [1] is involved with the ability to handle an arbitrary arrangement of reinforcement layers taking into account also the stiffening effect of concrete compression strut. Moreover, the shift rule can be activated in Concrete settings to incorporate into the design forces an additional tensile force in reinforcement caused by the shear. Detailed info about the whole recalculation procedure can be found in the Theoretical background.

 

Usage

  1. Calculate a FEM analysis of the model containing any 2D concrete member
  2. Go to Tree > Concrete > Reinforcement design > 2D members > Internal forces
  3. Set properties of the command to specify mainly:
    • selection of 2D members where the results are evaluated
    • load type from which the results are derived
    • specific result value from the available list to be visualized
  4. Click on [Refresh] action button to display the results

Note: To get general overview about how to work with a result services in Scia Engineer, see Results/Basics.

Properties

Category Property Description / Notes
Selection

Type of selection
All / Current / Advanced / Named Selection

Specifies on what members the results are displayed
See "Type of selection"

 
Filter

No/ Material / WildCard / Layer / Thickness
Result case

Type of load
Load cases / Combinations / Classes / NonLinear Combinations

 Defines for what load the results are displayed.
See "Result case"
Extreme 2D

Averaging of peak
On / Off

Activates averaging of peaks of results in places where averaging strips are applied.
See Results/Tools/Averaging strip
See Results/Theory/Averaging_peaks

Rib
On / Off

 

 Controls whether the components of internal forces parallel with the direction of the rib are neglect in area of effective width (the forces are recalculated to 1D results of the rib instead).
See Results/Theory/Rib_option
Location
In centres / In nodes no avg. / In nodes avg. / In nodes avg. on macro

Determines way how results - calculated in the nodes of individual finite elements - are further processed (averaged) to get smoother continuous distribution.
See Results/Theory/Smoothing_results

System
LCS mesh element / LCS - Member 2D

 Sets a coordination system which is used as referenced for displaying the results.
See Results/Theory/Local_axes_2d

Extreme

Mesh / Member / Global

 Defines for which extreme on 2D member the results are displayed.
Type of values

Design internal forces/ Design membrane forces / Basic internal forces

Categorizes result values into the logical subgroups.
Value

Defines what result value is graphically presented.
See the chapter Values below.

Output
Brief / Standard / Detailed

 Displays numerical output with given level of detail.
See the chapter Output below.
Standard result
On / Off		 Displays standard results on 2D members.
Results on sections
On / Off		 Displays results on the selected sections defined on 2D members.
Results on edges
On / Off		 Displays results on the edges of selected 2D members.
Deformed structure
On / Off		 Displays results on deformed structure.
Errors, warnings and notes settings   "Errors, warnings and notes settings"
Drawing Setup 2D   Serves for adjustment of graphical output
see "Drawing setup 2D"

Values

Design internal forces

The design internal forces represent a pair of bending moment (mEd) and axial force (nEd) calculated in each direction of the reinforcement (and concrete strut) by transforming the design membrane forces from the member surfaces into the centroidal plane.

Value Description Notes
mEd,1+

design bending moment in the direction of the first layer of the reinforcement mesh at upper surface

1) The upper surface [+] of the member is always considered on the side of positive local axis z of the member while the lower surface [-] is the opposite.

2) The first layer [1] of the reinforcement mesh is always considered as the one closer to the member surface (with smaller cover), while the second layer [2] is closer to the centroidal plane of the member.

 

 
mEd,2+

design bending moment in the direction of the second layer of the reinforcement mesh at the upper surface
mEd,c+

bending moment in the direction of the concrete compression strut stiffening the reinforcement mesh at the upper surface
mEd,1-

design bending moment in the direction of the first layer of the reinforcement mesh at the lower surface
mEd,2-

design bending moment in the direction of the second layer of the reinforcement mesh at the lower surface
mEd,c-

bending moment in the direction of the concrete compression strut stiffening the reinforcement mesh at the lower surface
nEd,1+

design axial force in the direction of the first layer of the reinforcement mesh at the upper surface
nEd,2+

design axial force in the direction of the second layer of the reinforcement mesh at the upper surface
nEd,c+

axial force in the direction of the concrete compression strut stiffening the reinforcement mesh at the upper surface
nEd,1- design axial force in the direction of the first layer of the reinforcement mesh at the lower surface
nEd,2- design axial force in the direction of the second layer of the reinforcement mesh at the lower surface
nEd,c- axial force in the direction of the concrete compression strut stiffening the reinforcement mesh at the lower surface
vEd design shear force

Be aware, the design bending moment and axial force must always be combined when you want to perform a uniaxial design in each direction.

When a direction of reinforcement is equal for both surfaces, it’s obvious the design forces in this direction are generally the same regardless of what surface is considered. However, to emphasize only the bending moments relevant for each surface, as non-zero are generally kept the moments causing tension in the reinforcement (meaning for the upper surface mEd+ ≤ 0 while for the lower surface mEd- ≥ 0). Such approach is also valid when the design forces are presented on sections or edges of 2D members.

Design membrane forces

The design membrane forces represent direct forces in the reinforcement directions (or concrete strut) at member surfaces.

Value Description Notes
n1+

design membrane force in the direction of the first reinforcement layer at the upper surface

1) The upper surface [+] of the member is always considered on the side of positive local axis z of the member while the lower surface [-] is the opposite.

2) The first layer [1] of the reinforcement mesh is always considered as the one closer to the member surface (with smaller cover), while the second layer [2] is closer to the centroidal plane of the member.
n2+ design membrane force in the direction of the second reinforcement layer at the upper surface
nc+ membrane force in the direction of the concrete compression strut at the upper surface
n1-

design membrane force in the direction of the first reinforcement layer at the lower surface
n2- design membrane force in the direction of the second reinforcement layer at the lower surface
nc- membrane force in the direction of the concrete compression strut at the lower surface

Basic internal forces

The basic internal forces represent the same magnitudes as in Results > 2D members > 2D internal forces.

 

Output

Type of value Graphical Numerical Notes
Design internal forces

 
Design membrane forces
Basic internal forces