To attach a spring support to a joint

§    Select the joint or joints supported by springs

§    Choose Joint Spring   from the Frame menu

A dialog box will appear with icons for the spring directions.

§    Click on the icon which shows the direction in which the spring is to act

§    Type in a value for the spring constant

§    Choose the axis system of the spring.

§    Select the type of spring.

§    Click on the OK button

Selecting the "No spring" icon (the first icon in the list) will remove all springs from the selected joints.  Selecting any other icon will remove any restraints or prescribed displacements with the same degree of freedom (if any) from the selected joints and replace them with springs.  The rotational spring icons each have an axis drawn through them in the 3D view that indicates the axis about which they provide rotational stiffness.

Springs acting in a local axis system are aligned to the local axis system of the node to which they are attacked.

Springs may also be defined as tension or compression only. As the behaviour of the spring is no longer linear, only a nonlinear analysis considering tension/compression only effects will correctly model these types of springs. In all other analyses the springs will be treated as a normal spring with no tension/compression only effects.

All restraints, springs and prescribed displacements that are applied to a joint are specified in the local coordinate system at each joint. The local coordinate system is typically the same as the global coordinate system but can be modified using the Joint Orientation feature described later in this chapter.

After you have added a spring to the frame, you can change its properties by double clicking on the spring icon in the Frame window. You can also edit the individual stiffness’s of the spring in the Springs table in the Data window.