Need a book? Engineering books recommendations...
Re: Wind Pressure Below Grade?[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: Re: Wind Pressure Below Grade?
- From: Rick.Drake(--nospam--at)fluordaniel.com
- Date: Wed, 2 Sep 1998 16:33:19 -0400
Brian A. Peterson wrote: <<I am looking for information and/or opinions on wind pressures at the below grade level. We install temporary containment structures in graving docks to blast/paint ship's structure. The docks are 30 to 60 ft. deep adjacent to the water's edge, and ~100 ft. wide by ~1000 ft. long. A containment may be installed in the base of the dock then rise above the "ground" level. For design, at above dock height I use standard wind load calculations from UBC and/or ASCE 7-95. At dock height and below, for lack of other criteria, I have used 10 psf based on ASCE 7-95 "minimum design wind loading." Depending on the depth below "ground" level, this may or may not be conservative. To add to the problem, any ship in dock will undoubtedly have a channeling effect on the wind- but that's another story. Barring major wind tunnel testing (not justified for temporary structures(?)), I would like an idea of whether or not I am on track with these assumptions. Any help is appreciated.>> ************************* Another way to look at this problem is to consider what happens as the wind stream hits the abrupt obstruction of a building. The windward side experiences a positive pressure and the other sides and roof experience a negative pressure. The wind going into your pit like a negative obstruction and is going to put both positive and negative pressures on your pit walls and any ship surfaces in the pit. In this line of thinking, I would use the wall pressure coefficients from Figure 6-3 of ASCE 7-95, Cp = +0.8 to -0.7. I would calculate qz based on 60 feet and appropriate exposure category. Running out the numbers will give you close to 10 psf for Exposure Category C. Your number of 10 psf as a minimum seems reasonable. Make sure you apply it both positive and negative. Rick Drake, SE Fluor Daniel, Irvine
- Prev by Subject: RE: Wind Loads on Monopoles
- Next by Subject: Wind Pressure Below Grade? N
- Previous by thread: Wind Pressure Below Grade? N
- Next by thread: Wood - Lateral columns and knee braces (kickers)