When defining a wind load by means of a user defined wind pressure versus elevation or wind velocity versus elevation profile, how does ceasar know where the ground level is in relation to the pipe to be able to apply this?

Adjust the global co-ordinate on the spreadsheet so that the elevation above which you are doing the wind analysis matches with your model.

Anindya Bhattacharya

I can't do that as we work in site co-ordinates so my model may be at an elevation of 110m. I suppose I have to allow for the fact when building the wind profile that a point 5m above the ground is actually at 115m in site co-ordinates and so apply the wind profile at 115m not 5m.

By default CAESAR II assumes that the coordinates of the first node in the model are (0, 0, 0). You can adjust this coordinate using the [Alt+G] key combination when in the piping input processor.

For a wind analysis, you would typically adjust the vertical coordinate as necessary, to position the system properly in the wind stream. (Note, wind is always assumed to start at an elevation off the ground of zero.)

So even if you're working in site coordinates, you should still be able to adjust the elevations to obtain the proper wind profile. Your conclusion is correct, you want to offset your wind profile. You could set up your profile table as:


where "x1" and "x2" are your velocity or pressure values.

To check this out, build a 1 element model, put it at the same elevation as your real system, apply the same wind, and verify with a hand computation.