02g. "Wind" - AutoPIPE Load Case

Comments Questions and Answers about Wind loads

Item #1: Comment

The Load> Wind command enables the user to define static wind load cases (W1 - W10) by generating wind pressure:

Vs. Profile piping height profiles

Per ASCE 7 1998, 2002, or 2010 code

Per Uniform Building Code (UBC) requirements.

After specifying a new wind load case, select the first cell in the left column to highlight the row and press the Modify button to see more settings for the specified Wind Load Type as indicated below:

The wind force is applied as uniform loads in the local coordinate system of the straight pipe or bend element. The equivalent wind force is assumed to act through the centroid of the element.

Wind loads will only be applied to piping if both conditions are meet:

1. segments that have "Applied Wind" checked on. I

2. Wind load case must be enabled inside of an analysis set:

Segment Tab on the input grids:

Load> Static Analysis Sets> modify analysis set:

Item #2: Comment

AutoPIPE 11.02.00.08 and higher: Wind loads defined in the model can be applied to that structural member.

AutoPIPE 11.01.xx and lower: Beam members are not subjected to wind loads, enhancement has been logged, (135281).

Item #3: Comment

In order to exclude piping inside a building from wind loads, the piping inside should be entered as a separate segment(s) from the piping outside the building.

Segment Tab on the input grids:

With the model Input grid opened, select the Segment tab, see column labeled "Apply Wind". Segments with Applied Wind enabled are considered outside, while segments with Apply disabled are considered inside.

Item #4: Comment

When specifying wind load profile elevation values, remember to check that ground is correctly defined on the main Wind dialog screen. This applies also to wind loadings per ASCE-7 and UBC.

Opening older AutoPIPE models may display a warning message "negative elevations found" may indicate an incorrect wind loading across this model.

If the Wind Ground elevation value was found to be greater than all the vertical pipe coordinates in a model, than the entire model would be considered to be underground and thus no Wind load will be applied. Confirm Wind load ground elevation relative to the piping model.

Item #5: How is the ground elevation determined for a Wind load case?

Item #6: How to input a Wind profile using Wind Velocity instead of Wind Pressure?

Item #7: How to account for East and West wind in both +ve and -ve directions?

Item #8: Will "Inclined" wind direction set to off global axis take care of user required eccentric, torsional, or pitched loading of FPSO or off shore platforms?

Item #9: Should the Wind Shape Factor Multiplier be 1 or 0.7 when using the ASCE wind specification type?

Item #10: How to apply the same wind speed over the entire model?

Item #11: How can the pipe movement be greater than the support gap setting for wind load combinations?

Item #12: Is the pressure used in a wind profile the basic pressure (i.e. acting on a plate), or do I have to adjust the pressure for a pipe when inputting the figure?

Item #13: What is the interpretation for annual probability and its relevance for determining wind load in AutoPIPE?

Item #14: Is there any way to consider friction only the expansion case but not in any occasional Wind loads?

Item #15: Does AutoPIPE count pipe insulation thickness towards the effective diameter for wind/wave force calculations?

Item #16: Where can one find information on ASCE 7 Wind speeds?

Item #17:

The following only affects AutoPIPE V8i 09.06.00.15 and will be fixed in the next new version 09.06.01.xx and higher:

The Ground Elevation for Wind is always entered in Feet, regardless of the model units file specified on Tools> Model Options> General dialog . This can be confirmed with the Loads Summary Data Listing report using any metric units file (CAE-TR-11097).