Just when you thought it was safe to go back in tall buildings, new research indicates that some high rises may have steel frames that could fail in a severe earthquake:

https://www.eenews.net/greenwire/2018/06/14/stories/1060084489

This is no surprise to many engineers familiar with damage to steel frame buildings in the Northridge Earthquake in 1994 and the San Fernando Valley Earthquake in 1971. The only "Proof Of Design" of a large building is to actually have a moderately severe earthquake and see if it experiences limited failures.

However, if there's a really severe earthquake (and it fails miserably), then someone's behind will roll.

 

Gee, I’ve worked in three of those buildings. Definitely felt the 1984 quake in 50 Fremont Center. Rolled around in my chair on the plastic pad. At the DEC office next door a friend discovered that there was a joint in the floor of his office. Made for an interesting effect when part of the floor moved one way and the rest another. Whoo hoo! ( I was at home in the east bay in 1989 ).

 

When I need to see what works in earthquakes I look at Japan.

 

When I need to see what works in earthquakes I look at Japan.

Coming from the Chicago area, I would expect there to be a gap between whatever the design called for and inspectors approved, versus what really got built. I wonder how this "gap" varies with geography. I suspect there is less gap in Japan than in San Francisco or Chicago. And I'm sure there are even bigger discrepancies elsewhere in the world.

 

Coming from the Chicago area, I would expect there to be a gap between whatever the design called for and inspectors approved, versus what really got built. I wonder how this "gap" varies with geography. I suspect there is less gap in Japan than in San Francisco or Chicago. And I'm sure there are even bigger discrepancies elsewhere in the world.

The Plains States should also have provisions for moderate to severe seismic activity. Chicago is near the New Madrid Fault Zone and in 1811 and 1812 there were two severe earthquakes in that region.

By the way, Japan's building codes were actually derived from California's codes which were based on events in the 1970's and 1994. As severe earthquakes occur throughout the world, the data for Peak Ground Acceleration (PGA) keeps coming in and the numbers seem to be getting worse. Arriving at a safe design seems to be like hitting a moving target.

 

https://www.express.co.uk/news/worl...quake-warning-natural-disaster-southern-Japan