Limit force

This feature may be useful if a 1D member is capable of bearing tension (or compression) stress up to a certain limit. The limit is specified by the limit value of axial force input in its absolute value. When the limit value is reached, two types of behaviour may occur: (i) the 1D member loses its stability and its bearing capacity drops to zero, or (ii) plastic behaviour get into action.

The following stress-strain diagrams demonstrate available options:

Limit compression force combined with loss of stability	$image\beamnonlinLimitPressBuckling.gif$
Limit compression force combined with plastic behaviour	$image\beamnonlinLimitPerssPlastic.gif$
Limit tension force combined with loss of stability	$image\beamnonlinlimittensionbuckling.gif$
Limit tension force combined with plastic behaviour	$image\beamnonlinLimitTensionPlastic.gif$

When inserted into the model, a 1D member with this type of nonlinearity is marked by the following symbol (remember that in order to see the symbol, view parameters must be adjusted to show model data).

$image\WndBeamNonlinLimitForce.gif$

Parameters

Direction

Either Limit tension or Limit compression may be selected.

Type

Buckling: If the limit force is reached, the 1D member loses its stability and bears no load at all.

Plastic yielding: If the limit force is reached, the 1D member follows the plastic stress-strain diagram.

Marginal force

Specifies the value of the limit force.