Using the Frame Analysis Spreadsheets

Following some recent questions in the comments, here are some answers:

How can nodal moments be created?

The current versions only allow for forces to be applied to beams, but any point load or moment applied at the start or end of a beam will in effect be applied at the node, so set “Position” to zero for any beam starting at the node, or to the beam length for a beam ending at the node.  In Frame 4 (the 2D version) all moments are applied about the Z axis.  In 3DFrame moments are applied about the global axis specified in “Direction XYZ” (Column C).

How can hinge or spherical joints, or bushing joints be created?

Both Frame4 and 3DFrame allow either end of a beam to be given a rotational spring stiffness.  If the stiffness is set to a very low value the beam ends will in effect be free to rotate.  In Frame4 rotations are about the Z axis.  In 3DFrame the rotations are relative to the beam principal axes, which are described here:  3D Frames, axes and stiffness matrices.

3DFrame also allows beams ends to be allocated a translational spring release along any of the three principal axes.

The example frame in each of the download files illustrates the use of the beam end springs.

How can multiple point restraints be applied?

Nodes can in effect be restrained to move together by connecting with very stiff members, with any required end hinge conditions, to provide the required restraint.


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