2D internal forces

The 2D internal forces command serves for displaying internal forces on selected 2D members.

Usage

  1. Calculate a FEM analysis of the model
  2. Go to Tree > Results > 2D members > 2D 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 service and its commands, 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 case / Combinations / Classes / Nonlinear Combinations/ Stability Combinations / Mass combinations

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

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

No / Mesh / Member / Global

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

Basic magnitudes / Principal magnitudes / Elementary design magnitudes / Resultant

 Note: for the "Resultant" of internal forces on a section, and the direction, please see "Displaying the resultant in the section across a slab" .
Value See table Values below.
Standard result
On/Off		 Display standard results on 2D members.
Results on sections
On/Off		 Display results on defined sections on 2D members. Note: for the "Resultant" of internal forces on a section, and the direction, please see "Displaying the resultant in the section across a slab" .
Results on edges
On/Off		 Display results on the edges of selected 2D members.
Drawing Setup 2D   "Drawing setup 2D"
Errors, warnings and notes settings   "Errors, warnings and notes settings"

Values

The following categories of internal forces can be displayed:

Basic magnitudes

The basic internal forces are default magnitudes referring to the local axes of the selected coordination system.

Value Description Notes
mx

bending moment in direction of local axis x

1) As default, the internal forces refer to the local axes of the individual finite (mesh) elements.

2) The local axes can be displayed by selecting the corresponding option in the View parameters settings.

 
my bending moment in direction of local axis y
mxy torsional moment
vx shear force in direction of local axis x
vy shear force in direction of local axis y
nx axial force in direction of local axis x
ny axial force in direction of local axis y
nxy in-plane shear force

Principal magnitudes

The principal internal forces represent the extreme values of the internal forces derived from the basic ones by transformation into the directions of principal axes:

Value Description Notes
m1

principal bending moment (max)

1) The angles of principal magnitudes are derived from to the local axis x.

2)The principal magnitudes can be visualized also as trajectories (see the option Trajectories in the command properties).
m2

principal bending moment (min)
ab

angle of principal bending moment m1

mtmaxb

maximum torsional moment
qmaxb

maximum shear force (from bending components)
bb

angle of maximum shear force qmaxb

n1

principal axial force (max)
n2

principal axial force (min)
am

angle of principal axial force n1

qmaxm

maximum in-plane shear force (from membrane components)

Elementary design magnitudes

The elementary design magnitudes represent design moments/membrane forces in directions of reinforcement considered as orthogonal and in alignment with the reference local axes (x,y). The calculation is based on the normal yield criterion referred as the Wood-Armer method [1] mentioned by ENV 1992-1-1, Appendix 2. Such solution provides sufficiently accurate results for manual design of plates/walls with just pure bending/axial loading without a significant torsion.

For type of structures with mixture of bending and axial loading (shells), with high torsional moments or in case the reinforcement is somehow rotated (skewed), a more advanced approach is required. Users with access to the Concrete module can use the design forces available there based on more sophisticated Baumann theory [2], see Concrete/2D members/Internal forces 2D.

Be aware, the elementary design magnitudes must not be combined! The design moments exclusively refer to design of plate reinforcement while design membrane forces are based on design of reinforcement in walls.

Value Description Notes
mxD+

design moment in direction of local axis x for reinforcement on positive surface


1) The positive surface is considered on the side of positive local axis z while the negative surface is the opposite.

2)The surfaces of the 2D member can be easily swapped by changing the z axis orientation (see parameter Swap in 2D member property list)
mxD-

design moment in direction of local axis x for reinforcement on negative surface


myD+

design moment in direction of local axis y for reinforcement on positive surface
myD-

design moment in direction of local axis y for reinforcement on negative surface
mcD+

complementary design moment in the concrete on positive surface
mcD-

complementary design moment in the concrete on negative surface
nxD

design force in x direction
nyD

design force in y direction
ncD

design force in concrete

Resultant

Value Description Notes
Fx

resultants of internal forces in direction of local axis x

 
Fy resultants of internal forces in direction of local axis y
Fz resultants of internal forces in direction of local axis z
Mx resultants of internal forces around local axis x
My resultants of internal forces around local axis y
Mz resultants of internal forces around local axis z
Components

possibility to choose more components in same time