Below is a CSiPlant piping model used to import and auto-combine with a SAP2000 structural analysis model. Users must have both CSiPlant and SAP2000 installed on their PC in order to import SAP2000 structural models into CSiPlant. The import procedure will tie up a SAP2000 cloud license only for 3 or 4 minutes, so it's not as if users need a dedicated SAP2000 license to integrate with CSiPlant piping models.
Using Edit menu>Add from SAP2000 model, CSiPlant can import detailed SAP2000 structural models including load assignments, releases, and mass model definitions, and auto-connect with the piping model using 2-point pipe supports for combined nonlinear pipe/structure analysis to obtain more realistic reactions and stresses. When importing SAP2000 structural models, CSiPlant maintains the same pipe support properties and labels used in the piping-only model, automatically converting 1-point pipe supports (connected to ground) into 2-point supports connected to frame elements. CSiPlant can import SAP2000 models from V21 to current version. User will be prompted to select which SAP2000 model to import. This will launch SAP2000 using the open application programming interface (OAPI).
Before the import is complete, 4 screens will appear. Depending on the version of the SAP2000 model, the first screen may display an UNIFHT function "error" which can safely be ignored since UNIFHT is a SAP2000 default power spectral density loading function which is not available in CSiPlant. The second screen in this example displays no errors but warnings which can also be ignored. CSiPlant does not yet have special rebar or tendon elements like SAP2000, and those discrepancies trigger warning messages even though the imported SAP2000 model did not contain any rebar or tendon elements.
The third screen is usually the most important to pay attention to, especially the Auto-connect supports tab shown below. If coordinates match between the piping model and structural model, CSiPlant default settings usually work very well. The default -Z direction tells CSiPlant to search for beams underneath the pipe support locations in order to auto-connect. In cases such as rod hanger supports where the piping is supported from above, users can switch direction to +Z if most piping is supported from above. However, if only a few are supported from above, go ahead and use the default -Z and then come back later and assign individual pipe supports to frame members above using Assign>Support connection procedure. The fourth and final import log screen has no errors, and its warnings in this example can be ignored.
If the combined piping with support structure model involves analysis of static accelerations (static seismic or transportation loads) or any dynamic analysis, users will usually need to modify the default Mass Source in the combined model. The default mass source for CSiPlant includes piping and frame member selfweight, fluid contents, insulation, inner liner, and cladding if modeled. However, structural analysis models almost always consider the weight of heavy equipment, cable trays and other objects with significant weight and mass by assigning gravity-direction distributed loads and/or gravity-direction concentrated point loads to represent the weight of those objects. Below left is the default Mass source after importing a SAP2000 model. This default Mass source ignores the gravity-direction loads included in the SAP2000 model.
Selected pipe support reactions from the combined model can be automatically exported back into the SAP2000 structural model, thereby saving time, confusion and errors associated with marked-up isometrics, spreadsheets, and other manual methods of communicating pipe support reactions from piping stress to the structural team. See Define menu>Support reaction export request to view options to selectively export by Load case, pipe section, Pipeline label, design request, and by support. CSiPlant can export individual load cases as well as load cases that include a combination of loads. After defining a support reactions export request and analyzing the model, in order to export pipe support reactions to SAP2000, go to Analyze menu>Export support reactions where you will be prompted to select the support request as well as select the SAP2000 model to which the support reactions will be exported.
Structural engineers typically model heavy equipment, cable trays and other objects with significant weight as gravity direction (-Z) load assignments using concentrated point loads and/or frame distributed loads. Those objects need to be considered not only as loads, but also as mass for static acceleration load calculations and for all dynamic analysis cases. CSiPlant offers the unique ability to selectively define “mass sources” which auto-converts selected gravity direction loads to mass in all 3 translational directions (X, Y, and Z).
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, 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 to rigorously consider the effects of pipe-structure interaction.
CSiPlant model after importing the support structure from SAP2000 and auto-connecting piping to the support structure.
