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After importing the SAP2000 structural model, go to Define>Load cases to modify the GR weight case to specify the Mass source as the one we just specified which was imported from SAP2000, and also add gravity-direction load patterns imported from SAP2000 which can potentially effect piping vertical displacements. Equipment loads, for example, are assigned to the structure, not piping, but they can nonetheless cause vertical (and lateral) displacements on the support structure which affects supported piping displacements and therefore can affect piping code stress calculations and end reactions.
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It’s not uncommon for pipe rack structures to be designed for lateral drift of Height/100 or Height/200 (Height of pipe rack) under wind or seismic loading which means 5" of allowable lateral deflection for a 42 ft. tall pipe rack, lateral deflections which can cause significant imposed displacements at pipe support locations. If it’s important, for example, to consider local nozzle/vessel flexibilities with a 3/4” imposed displacement at an equipment connection, then it’s also important to consider support structure flexibility and imposed displacements at pipe supports from the structure, particularly support structure displacements from lateral loads. CSiPlant and SAP2000 make it easy straightforward and reliable to rigorously consider the effects of pipe-structure interaction.
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