This page contains frequently asked questions related to solid elements.

General FAQ

Does SAP2000 support solid elements with less than 8 nodes?

Yes, SAP2000 does support the degenerate solids, where nodes are collapsed (duplicated) to make wedges and tetrahedra. The joints can be collapsed in any way as long as the operation does not create an illegal solid object

How can I draw solid elements in SAP2000?

Solid elements can be created either by extruding area objects via the "Edit > Extrude" menu command, or they can be defined via Interactive database editing. To use interactive database editing to define solid elements, open the interactive database editing via "Edit > Interactive Database Editing" and then edit the "MODEL DEFINITION > Connectivity Data > Object Connectivity > Table: Connectivity - Solid" table.

The program generated red springs on the joints of my solid elements. What are these for?

The red-springs are typically generated for solid objects with edge constraints. They are used to restraint the joints of the solid object from rotation.

Solid elements activate only three translational degrees of freedom at each of their joints. However, the implementation of the edge constraint activates three additional rotational degrees of freedom. Since the solid element does not provide any rotational stiffness at it joints, the program generates internal rotational springs at the affected joints to prevent local numerical instabilities due to zero rotational stiffness provided by the solid elements.

If these internal rotational springs were not generated, you would see warnings in the output log for zero stiffness at the affected DOFs. While these warning can could be ignored, but providing rotational springs eliminates them all together.