Wind loading debate

[maxwolf]

The old New York City Building Code(1968) allows for use of 30 psf wind loads for up to around 100ft for buildings. This is for the MWFRS as well as cladding to my knowledge. I've seen it used for both.

ASCE 7-02 and other versions of course require much higher wind loads for cladding (depending on panel size) in the range of 100 ft elevation. Say around 70 psf in some cases for suction on cladding at the corner of a facade.

I would design for the higher ASCE 7 load, even if the old code allows me to use the 30 psf. ASCE 7 is supported by the latest research for one, and the difference is > 2:1. Another engineer argues that the old code is still legal for some projects and that as long as we satisfy the code, we've done our job; and nothing is flying off buildings in NYC(so far as we can remember), so it must be reasonable.

Any suggestions on how to get a better understanding of the physics and issues behind this?

 

[weab]

Just because nothing has happened so far (as far as you know) is not a good reason. Perhaps a design wind load has not occured at your building.

The current NYC building code should tell you what is adequate, 1968 or current code. Even if 1968 is allowed, I'd advise client of this and let them make decision. You client will not be happy if they have to replace torn off cladding next year.

I agree with you. I'd recommend using the current code due to improvements in wind loading code.

 

[paddingtongreen]

There is an expectation in all contracts, whether stated or implied, that the EOR will perform the work with due diligence.

Hanging ones hat one the technicality that allowed one to use an an old loading that has been shown to be inadequate won't do any good in court if there is a failure.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Ron]

jsd is right....the buildings have not seen the design loads, but we should design for them anyway. That engineer is thinking like a contractor.

Michael's comment about diligence is on target. We are required to exhibit a reasonable standard of care. To design for a lower load because of old technology or information when we know the research and technology do not support that, in my opinion, violates a reasonable standard of care.