05. If the Harmonic imposed displacement forcing function is applied to an anchor, why is that anchor not displaced the amount in the Displacement report for that AutoPIPE Harmonic load case?


	Applies To

	Product(s):	AutoPIPE
	Version(s):	All
	Environment:	N/A
	Area:	Analysis
	Original Author:	Bentley Technical Support Group
	Date Logged & Current Version	Nov. 2015 10.00.00.10

Problem:

If the Harmonic imposed displacement forcing function is applied to an anchor, why is that anchor not displaced the amount in the Displacement report for that Harmonic load case?

Example:

A10 is an anchor, on the Harmonic Load dialog screen, set Input = Impost displacement, Dy = 5.0 inch

Analyze, and Review results displacement report

why is movement at A10 = 0.00 for all directions.

Solution:

Harmonic loads applied to a support (i.e. anchor) may not present the correct restraint reactions without ZPA and / or missing mass enabled.

Additional information:

1. All non-force harmonic inputs are converted to displacements, then to forces using the stiffness matrix of the anchor. It is this force that is then applied to the structure.

2. AutoPIPE's missing mass is applied to the structure based on the theory of Old Edvard Hansteen in his article titled "On the accuracy of mode superposition analysis in structural dynamics".

05. If the Harmonic imposed displacement forcing function is applied to an anchor, why is that anchor not displaced the amount in the Displacement report for that AutoPIPE Harmonic load case?

Problem:

Solution:

See Also