We're currently doing analysis work using NBC-2005 for Wind Loads on elevated piping systems. A comparison was made between using NBC-2005 and the Wind Pressure vs. Elevation by modeling 3 identical 1-meter pipe segments located at 5, 10 and 15-meter elevations. The base of each 1-m pipe segment was anchored and the top left free (like a stack).

The restraint summary showed that the NBC-2005 method had identical Fx=483N at anchor points for all 3 elevations (i.e. 5, 10, 15 meters). While on the Wind Pressure vs. Elevation method the results showed varying Fx results for the anchors points- 1133N for 5 meters elev., 1259N for 10 meters elev. and 2037N for 15 meters elev.

It appears the NBC-2005 method is not taking into account the elevations of the pipe segments. We were expecting results for effects of wind to vary with elevation. Is the NBC -2005 accurate or is our method not right?

Have you confirmed that your three anchors are at three elevations?
I believe these wind profiles use a minimum value until a certain elevation. Have you confirmed that you have exceeded that minimum elevation?

Good to hear back from you Dave!

Yes, I have confirmed that the three anchors are at three elevations. What is the minimum elevation in relation to the wind profile and how would you define that? Is it the "Height of the Windward Face"? What I know is that the wind load increases in a curve as the elevation increases. Based on what you mentioned I'm thinking that the effects of wind will be more evident and will increase if I had one continuous segment from 0-15 meters vs. having 3 separate segments. I would really appreciate help on this.

Thanks,

George,

I'm getting different loads with increasing elevation. I ran pipe in X and wind in Z. The anchors at 5 & 10 meters show the same load and the 15m anchor had a higher load. The 5 & 10 meter elevations show the minimum load.
I did not specify the Height of the Windward Face.

Dave,

Yes, you're right. I found that out too. I added more 1-meter pipe segments beyond the 15-meter elevation and the loads at the anchors started increasing. Just like how any wind profile should behave the loads would not increase until a minimum elevation is reached-just like you mentioned. Thank you for the help.