Seismic Anchor Motion SAM

Seismic Anchor Motion SAM

The Seismic Anchor Motion or SAM is used to determine the response of a system to the differential movement of structures during a seismic event. The levels of a structure (or structures) are said to be in phase if all points on the level or structure move in the same direction at the same time during the earthquake.

The method considers the movements in the three spatial directions, grouping the points by a phase number, which describes the relative displacement of the point with respect to the other points of the system.

Although SAM analysis is used to determine the response of the structure to dynamic loading, linear static analysis is used to calculate the maximum response of the structure to differential movements of various points in the structure. A matrix {R} consists of imposed seismic movements only.

SAM Analysis is combined with seismic movements calculated by multiple spectra, since being several structures, each one has its response spectrum.

In tall structures the Response Spectra in each direction are usually different.

Response Spectrum Analysis

AutoPIPE can apply up to 50 response spectra to a piping model.

The spectrum response analyses that can be performed with AutoPIPE are:

Multiple response spectra

For multiple spectra, groups of supports are defined and the spectra are applied to each group on each axis.

Selecting the supports for each group is simple as the Elevation Support Selection Tool can be used.

Normally the ground level has a base spectrum calculated according to the standard and the following levels must be calculated based on the structure and for each direction.

AutoPIPE will automatically create the equations for stresses according to the standard you are using.

Assignment of displacements for SAM analysis

Multiple Response Spectra and SAM

In case the piping system is supported by two or more structures, an analysis with the movement of the supports (SAM) must be additionally performed and combined with the multiple spectrum analysis.

SAM is a static analysis based on the deformations caused by the movement of the supports. It is very important to do it whenever the pipes are supported since the structures will have different natural modes of vibration and therefore, they will move in a non-solidary way.

Multiple Spectral Analysis of a Combined Pipe and Pipe Rack System