Building a Supertall in 1930's San Francisco.

[Tyler Xyroadia]

A friend of mine who is a bit of an Alt-History fiend has been writting a story that has a huge company based in SF.
The late 20's and 30's were the hayday of Supertalls in NY, and he wonders if it was, given the prepensity for Earthquakes, structurally possible to build a tower 40 to 60 stories tall that would be considered safe using 1930 materials.

Hoping a friendly Engineer may enlighten things.

[scalziand]

It might have been possible. By 1927, seismic design was incorporated into the UBC, which was used in San Francisco. However, these early provisions were later discovered to be incomplete, requiring revisions in the following decades. The Richter scale wasn't developed until 1935, and actual measurements of the accelerations and displacements in an earthquake weren't obtained until the 1933 Long Beach earthquake. With out the measurements of what actually happens in an earthquake, it would be difficult to come up with a design, especially with the crude design tools.

Appendix A: History and Principles of Seismic Design
http://en.wikipedia.org/wiki/Seismic_analysis

http://www.curee.org/image_gallery/c...EE_excerpt.pdf

A steel tower design using the early incomplete tools would probably have survived a moderately severe earthquake, but with significant damage. I'm not positive on that though. A tower designed in the late 30's might have a better chance.

[Tyler Xyroadia]

AH! Thank you much for the information.

"Supertall" was a bit much in truth, it seems at most he was thinking of a building about 500 to 525feet tall. Seems he wanted to make sure that even that would be "Safe" using 1920's materials. So building something in 27 or 28 could incorporate the most recent structural advances.

[Dralcoffin]

Originally Posted by Tyler Xyroadia

AH! Thank you much for the information.

"Supertall" was a bit much in truth, it seems at most he was thinking of a building about 500 to 525feet tall. Seems he wanted to make sure that even that would be "Safe" using 1920's materials. So building something in 27 or 28 could incorporate the most recent structural advances.

By 1930 San Francisco had two buildings at 435 feet and LA City Hall is 454, so another hundred feet was likely possible. However, I know LA City Hall has needed extensive earthquake proofing. As scalziand summarized in his post, it seems to me that knowledge, not technology, is the main hurdle to an Art Deco skyscraper in San Francisco.

[THE BIG APPLE]

A SUPERTALL in 1930, not really likely. One in the next two decades (or even a decade) is VERY likely, in fact almost guaranteed.