Wind Loading: Shielding on multiple parallel frames
Wind Loading: Shielding on multiple parallel frames
(OP)
I have a situation where multiple bays of racking will be subject to wind loads.
Looking at the shielding factor (Ksh) for multiple parallel frames given in AS1170.2 Appendix E, it appears that Ksh does not reduce for multiple parallel frames. For equally spaced, identical frames according to Table E2, lambda and the solidity ratio stay the same and so the shielding factor for every leeward frame is the same.
It seems counterintuitive that the 20th bay of racking (counting from the windward frame) receives the same load as the 2nd.
I have very many bays of racking and the overall load is many times higher than an equivalently sized clad building.
Am I calculating lambda correctly (spacing between adjacent frames/smallest overall dimension)?
Or should the "frame spacing" for each frame be its distance from the windward frame?
Thanks
Richard
Looking at the shielding factor (Ksh) for multiple parallel frames given in AS1170.2 Appendix E, it appears that Ksh does not reduce for multiple parallel frames. For equally spaced, identical frames according to Table E2, lambda and the solidity ratio stay the same and so the shielding factor for every leeward frame is the same.
It seems counterintuitive that the 20th bay of racking (counting from the windward frame) receives the same load as the 2nd.
I have very many bays of racking and the overall load is many times higher than an equivalently sized clad building.
Am I calculating lambda correctly (spacing between adjacent frames/smallest overall dimension)?
Or should the "frame spacing" for each frame be its distance from the windward frame?
Thanks
Richard






RE: Wind Loading: Shielding on multiple parallel frames
I have a little cheat sheet on my office wall to show which codes allow partial shielding, no shielding, full shielding. None of the codes I work with in the US are consistent about it.
Hopefully one of our southern hemisphere contributors will be able to more specifically address your question.
RE: Wind Loading: Shielding on multiple parallel frames
If you think about first frame being in undisturbed air, second and subsequent frames are in disturbed air and still subject to the same wind speeds/pressures it all seems to make sense to me. A further reduction for each subsequent would mean lower wind speeds/pressures as you get further from the first frame, this isn't the case.
RE: Wind Loading: Shielding on multiple parallel frames