Code Prescribed Wind Loads 1930's

[FisherStruct]

I am working on the renovation of a building constructed in the 1930's. It consists of steel framing and unreinforced brick masonry walls. Does anyone know the wind load requirements in the AISC Manual of Steel Construction or any other code that may have been applicable at that time? Thank you...

 

[JAE]

I don't know what would have been in effect then, but I wonder why you would need to know? Are you trying to establish some correlation with the current condition or something?

 

[dbuzz]

I have a copy of Ketchum's Structural Engineers Handbook (1924), which has some information about wind loads.

Steel Mill Buildings
Wind Pressure:
p = 0.004V²
where:
p: wind pressure on a flat surface normal to the wind direction, in pounds per square foot
V: wind velocity, in miles per hour

For rectangular buildings, Ketchum suggests using 80% of the above value and concludes that 30psf '...would be sufficient...' for all except exposed locations and that 20psf '...is certainly ample...' if the building is somewhat protected and the height is less than 30ft.

Steel Office Buildings
The following values are extract from a Carnegie Steel Company table, based on the building laws of various cities:
[ul][li]New York (1917): 30psf[/li]
[li]Chicago (1919): 20psf[/li]
[li]Philadelphia (1919): 30psf. Wind pressure for high buildings in built-up districts: 25 pounds at tenth story, 2.5 pounds less for each storey below and 2.5 pounds for each storey above, up to 35 pounds.[/li]
[li]St Louis (1917): 30psf[/li]
[li]Boston (1919): 10-20psf. For buildings 40ft high, 10psf; up to 80ft, 15psf; over 80ft, 20psf.[/li]
[li]Cleveland (1920): 20psf. Wind pressure on curtain walls, 30psf[/li]
[li]Baltimore (1908): 30psf[/li]
[li]Pittsburgh (1914): 25psf[/li]
[li]Cincinnati (1917): 20psf[/li]
[/ul]

 

[FisherStruct]

In response to JAE:

The city that I work in wants to demolish a portion (~20%) of an existing building to make way for a developer to build a hotel. Demolishing this portion of the building would remove some masonry shear walls. We spoke with the city code official, and the official stated that as long as the remaining portion of the building can be shown to resist the lateral loads that were prescribed at the time of construction it is acceptable.

In response to dbuzz:

Thank you for the good information.

 

[SlideRuleEra]

FisherStruct - I have posted the 1940 ASCE recommendations for wind loading at my website (link below) - near the bottom of the home page.

From another source, a 1934 summary of wind loading equivalent static pressure is in general agreement with the data that dbuzz has offered.

http://www.SlideRuleEra.net

 

[archeng59]

some of the older engineers used 15 psf (total lateral wind pressure) for buildings up to 5 stories (this is in Oklahoma), based on previous discussions about the current code complexity. for buildings over 5 stories, they referred to something called the Chicago code, which gave various pressures at different levels for tall buildings. don't know how to get a copy of whatever that is, but maybe someone has heard of it.

 

[JAE]

FisherStruct - I would say that the city code official is wrong - but he/she is the "boss" here I guess. There is no earthly reason why a current building, designed long ago, should EVER be validated by the code that it was originally built under.

The city or governing agency under which the building exists is legally covered by a contemporary building code that requires certain prescriptions as to wind capacity and shearwall design. That is the legal document that the building code official is hired to enforce, not a 1930's era code.

 

[dbuzz]

It does seem unusual to check a structure against old and, presumably, withdrawn standards. Having said that, the City may take the view that it's unfair to 'penalise' a developer by making them retrofit a long-standing structure to ensure compliance with current codes when there are obviously many ageing buildings about which were not designed to them.

I recall reading a journal paper some years ago about the evaluation of old buildings to current standards, but unfortunately cannot recall which journal.