| Applies To | |||
| Product: | AutoPIPE | ||
| First Affected Version: | 9.2.0 | ||
| Found in Version: | 11.00.00.22 | ||
| Fixed and Released in Version: | 11.01.00.20 | ||
| Area: | All | ||
| Severity: | Critical | ||
| Backlog Issue Number: | 747811 |
Behavior
• Severity: 1 - Critical
• First Affected Build: 9.2.0
• Affected Product: AutoPIPE
• Affected Versions: Advanced and Nuclear
• Program Affected: Yes
• Program Help Affected: No
• Documentation Affected: No
Problem Description
Imposed support displacements inserted on supports and/or anchors that are connected to beam members are not considered for Multiple Support Response Spectrum (MSRS) analysis. In such cases displacements, forces and moments, support loads, and anchor loads may not be calculated correctly, leading to unconservative results..
Steps to Repeat
To illustrate this defect, the following scenario can be considered:
Step 1: Create a new ASME B31.1 model with English units
Step 2: Press Cancel on the Segment dialog that appears
Step 3: Define a new beam section in the model (Insert >Structure > Beam Section Properties) with the following properties:
Non Standard Section type
Shape: Pipe
Section name: Beam12
Outer diameter: 12.75 in
Thickness: 0.375 in
Material name: STEEL
Step 4: Insert a Beam in the model running 10 feet in X-direction from point 1001 to point 1002, using Section ID BEAM12 defined above
Step 5: Insert an anchor at point 1001
Step 6: Insert another beam starting from point 1002 and running 10 feet in Z-direction towards point 1003
Step 7: Insert another anchor at point 1003
Step 8: Insert an imposed support displacement at the anchor at point 1003 with the following data:
Load case to combine with: S1
Support Group No.: 1
Translation: X = 1.0, Y = 0.0, Z = 0.0
Step 9: Define a new Response Spectrum file (Loads > Spectrum > Response/Force) with the following settings:
Spectrum file name: Ground_Z
Seismic Code EURO(EC8): 2004
Interpolation Method: 1 Lin-Lin
Damping ratio: 5
Data Type (Freq/Per): Period
Leave the remaining field with their default values and press OK on the dialog.
Step 10: Open the Modal tab of Dynamic Analysis dialog and set the following fields:
Analyze up to cutoff frequency: Checked
Cut-off frequency (Hz): 1,000
Step 11: Navigate to the Response Spectrum tab of Dynamic Analysis dialog and create a new Response Spectrum load case with the following settings:
Analyze: Checked
MSRS: Checked
SAM Case: S1
Analyze Support Group: All
Spectra (Define) X-Spectrum = None, Y-Spectrum = None, Z-Spectrum = Ground_Z, Z-Scale = 1.0
Leave the remaining fields with their default values and press OK on the Dynamic Analysis dialog.
Step 12: Analyze the model and open the Anchor tab of Result Grids dialog
Notice that there are no anchor loads against Response 1 load case.
Create another model by repeating the procedure above, this time using a 12 in STD Pipe element instead of beam section. Notice that for the model with pipe elements, there will be some anchor loads against Response 1 load case.
Evaluation Criteria
The following considerations are provided to assist in your evaluation of the potential impact of this defect on the results:
1. Evaluate whether this defect has affected any existing models by considering the criteria below:
a. Was the model created or updated in program version 9.2.0 or later?
b. Was there any Response Spectrum load case with MSRS option enabled?
c. Were there any beam members in the model?
d. Were there any supports or anchors connected to beam nodes with Imposed Support Displacements combined with a SAM case AND that SAM case was used in an MSRS load case?
A 'No' to one or more of the above criteria means that this defect does not affect the model’s results. No further consideration for this model is necessary.
Workaround
Add a short length rigid pipe at the end of beam members that has anchor or support with SAM displacement. The anchor or support is then connected to a pipe node rather than a beam node, and is processed correctly for MSRS analysis by the program.
Solution
Imposed Support Displacement value should be applied correctly for MSRS analysis to supports and anchors that are connected to beam members.
Additionally, to assist in the screening of the models created in previous program versions for any potential impact by this defect, the program shall automatically examine the model database after opening the model and generate a report (model name + "_D747811.TXT"), listing the Response Spectrum load cases with results potentially impacted by this defect. The program shall display the following confirmation message:
“Results for Multiple Support Response Spectrum Analysis may be incorrect when imposed support displacement is inserted on supports connected to beam members due to a previous program defect #747811. Would you like to review the evaluation report?”
The contents of the critical error report shall be like the following sample critical error report:
Defect #747811 Evaluation Report
--------------------------------
Model Name: TEST1
Model Version: 09.06.02.06
Program Version: 11.01.00.20
Report Filename: TEST1_D747811.TXT
--------------------------------
Results for Multiple Support Response Spectrum Analysis may be incorrect when imposed support displacement is inserted on supports connected to beam members due to a previous program defect #747811. Please refer to the published defect report for more details, mitigation conditions and instructions. To assist in the screening of this model for any potential impact by this defect, program has examined the model database and has found that the results for the following Response Spectrum load cases may be incorrect. Model should be re-analyzed using this program version.
After saving this model or running any analysis in this version or later commercial release versions, this screening will no longer be performed.
Response Spectrum Load Case(s) potentially impacted by this defect:
-------------------------------------------------------------------
Response 2
Response 5
Also See:
Critical and High issues released in v.11.01.00
Known Issues in AutoPIPE (Enhancements, defects, etc..)