RamSeries manual


Constraints 

Data->Constraints 

Constraints and prescribed displacements

The parts of the structure that has any type of external constraint in their movements, are called constraints. These constraints can be applied for every degree of freedom (X, Y, Z and rotations for beams and shells), and for every node in the model

In this condition, the local axes have no relationship with the beam local axes defined in the properties section. The GLOBAL option means to prescribe related to the global axes of the problem. Local axes are used to prescribe the displacement or rotation in a direction not coincident with any of the global axes. The values part of the condition is used to prescribe a fixed amount of displacement or rotation. Default units are meters for the X, Y and Z displacements and radians for the prescribed rotations. X Constraint, Y Constraint and Z Constraint mean the displacements along the axes. Theta x Constraint, theta y constraints and theta z constraints mean the rotations around the axes. Signs are as follows (right hand rule):

 


This condition can be applied to either points, lines or in the solid analysis, to surfaces.

Note: 3D solids have only three degrees of freedom: displacements in X, Y and Z.

Elastic constraints

The elastic constraints are similar to the constraints but instead of prescribing the displacement or rotation of a point, an elastic spring is attached to that node for each prescribed degree of freedom. The first three constraints: X-constraint, Y-constraint and Z-constraint are the prescriptions for the three displacements. If any is set, a value must be given that represents the stiffness of that spring. The last three constraints: theta-X-constraint, theta-Y-constraint, theta-Z-constraint, are prescriptions for the three rotations

This condition can be applied to either:

It is possible to use a combination of normal and elastic constraints for the same point. The only condition is that every degree of freedom must have prescribed only a displacement or an elastic movement.

This constraint can be used in the analysis of foundations and interactions with the ground and terrain.