If you want a node to act as a support, at least one of its degrees of freedom must be restricted by a spring or blocked. In addition, the node must be a part of a surface or member. The forces, originating from the support and counteracting, are called support reactions.
Nodal supports are required to apply imposed deformations and can be provided with nonlinear properties (failure criteria for tensile or compressive forces, working and stiffness diagrams).
- Movable supports allow rotations around the support point and displacements in direction of the trajectory. The displacement perpendicular to the movement will be blocked. Movable supports are described as structurally single-valued due to the removal of a degree of freedom.
- Fixed supports or support hinges also allow rotations about the support point, but prevent horizontal or vertical displacement options. Fixed supports are described as structurally two-valued due to the removal of two degrees of freedom.
- Rigidly fixed supports block both rotation and displacement. Rigidly fixed supports are described as structurally three-valued due to the removal of three degrees of freedom.
Entering in RFEM and RSTAB
Nodal supports can be entered graphically and defined in RFEM and RSTAB by using 'Insert' → 'Model Data' → 'Nodal Supports' → 'Graphically', by using the corresponding button or tables of the Data Navigator.