Applies To
	Product:	AutoPIPE
	First Affected Version:	9.6.0
	Found in Version:	12.02
	Fixed and Released in Version:	12.03
	Area:	All
	Severity:	Critical
	Backlog Issue Number:	1053801

Behavior

Problem Description

AutoPIPE ASCE 7 (2002 and 2010 editions) wind analysis incorporates the wind speed-up effects for structure or piping on
hill or escarpment. For incorporating the wind speed-up effects, program calculates the topographical factor Kzt. The
topographical factor Kzt is in turn calculated from K1, K2, and K3 multipliers.

ASCE 7-02 (Note 2, Figure 6-4) and ASCE 7-10 (Note 2, Figure 26.8-1) requires limiting the height over distance upwind of
crest (H/Lh) value to 0.5 for evaluating K1 multiplier. ASCE 7 also requires substituting 2H for Lh for evaluating K2 and K3
multipliers when H/Lh exceeds 0.5. AutoPIPE wind analysis does not incorporate the two conditions above. This results in
incorrect pressure value calculations for wind load cases. In instances where the pressure value calculated by AutoPIPE for
wind load case is lower than the actual pressure value, the wind load case results may be unconservative.

Steps to Repeat

To illustrate this defect, the following scenario can be considered:

Step 1: Create a new ASME B31.3 2016 edition model with AUTOPIPE units

Step 2: Define a new pipe identifier with following data

Pipe identifier: PIP1
Nominal Diameter: 20.00
Schedule: STD
Pipe Material: A106-A

Step 3: Insert default data on Operating Pressure & Temperature dialog

Step 4: Insert an anchor at A00 and insert a run with following data

Generate points 5
Offsets DY 10 ft

Step 5: Insert Wind load W1 with following data

Type ASCE-7-10
Wind direction Global X
Wind speed 85.00 mph
Exposure category C
Consider wind speed-up Checked
Type of hill or escarpment 2-D Escarpment
Structure location Upwind from crest
Height of hill or escarpment(H) 40.00 ft
Distance upwind of crest (Lh) 20.00 ft
Distance from Crest to Struct (x) 120.00 ft

Step 6: Add wind load W1 to first analysis set

Step 7: Take out Loads summary data listing and notice “Pressure” value at 10 ft. as 3.406 psf

The value of 3.406 psf reported by AutoPIPE at 10 ft is calculated using incorrect values of K1, K2, and K3 multipliers.
Manually calculating K1 after limiting H/Lh value to 0.5 results in a K1 value of 0.425. Manually calculating K2 and K3 after
substituting 2H for Lh results in K2 and K3 values of 0.000 and 0.732 respectively. Using these values of K1, K2, and K3 results
in a pressure value of 9.342 psf while program is reporting 3.406 psf. This change in pressure value would result in increased
forces and moments for wind load cases.

Evaluation Criteria

The following considerations are provided to assist in your evaluation of the potential impact of this defect on the results:

Evaluate whether this defect has affected any existing models by considering the criteria below:

1. Was the model created or updated in program version 9.6.0 or later?
2. Was there any wind load with type ASCE-7-02 or ASCE-7-10?
3. Was there any wind load with “Consider Wind Speed-up” checkbox checked?
4. Is there any wind load case with H and Lh values such that H/Lh ratio is greater than 0.5?

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

None

Solution

ASCE 7 requires limiting the height over Distance upwind of crest (H/Lh) value to 0.5 for evaluating K1 multiplier. ASCE 7
also requires substituting 2H for Lh for evaluating K2 and K3 multipliers when H/Lh exceeds 0.5. AutoPIPE wind analysis
should incorporate the two conditions above.

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 + "_D1053801.TXT") listing the impacted wind loads in the model. The program shall display the following
confirmation message:

“Certain wind loads are not using correct boundary conditions for the calculation of topographical factor Kzt due to
previous program defect #1053801. Would you like to review evaluation report?”
The contents of the critical error report shall be like the following sample critical error report

Defect #1053801 Evaluation Report
--------------------------------
Model Name: TEST1
Model Version: 09.06.02.06
Program Version: 11.05.00.05
Report Filename: TEST1_D1053801.TXT
--------------------------------
ASCE 7 requires limiting the height over distance upwind of crest (H/Lh)
value to 0.5 for evaluating K1 multiplier. ASCE 7 also requires

substituting 2H for Lh for evaluating K2 and K3 multipliers when H/Lh
exceeds 0.5. AutoPIPE wind analysis does not incorporate the two
conditions above due to previous program defect #1053801. 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 pressure results for the wind load(s) listed below
may be incorrect resulting in incorrect forces and moments. Model should
be re-computed using this program version.
After saving this model or running any analysis in this version, this
screening will no longer be performed.
Wind loads potentially impacted by this defect:
-----------------------------------------------
Wind 1 Wind 4

Also See:

Critical and High issues released in v.12.03.

Known Issues in AutoPIPE (Enhancements, defects, etc..)

Bentley AutoPIPE