Santa Monica is poised to require safety improvements to as many as 2,000 earthquake-vulnerable buildings in what would be the nation’s most extensive seismic retrofitting effort.

Santa Monica’s safety rules would go beyond what Los Angeles has done by requiring not only wood apartments and concrete buildings to be retrofitted, but also steel-frame structures.

Steel buildings were once considered by seismic experts to be among the safest. But after the 1994 Northridge earthquake, engineers were stunned to find that so-called “steel moment frame” buildings fractured.

About 25 were significantly damaged, said structural engineer Ronald Hamburger, senior principal with Simpson Gumpertz & Heger in San Francisco.

No steel building suffered a catastrophic failure that took lives in that earthquake, but some were so badly damaged they had to be demolished. One — the Automobile Club of Southern California building in Santa Clarita, open for just 21 months — came very close to collapse, Hamburger said.

A year later, one story of a Japanese steel building collapsed during the 1995 Kobe earthquake.

Now, Santa Monica has decided to tackle what has been the third rail of seismic safety. It has been controversial because retrofit costs are significant, especially for tall skyscrapers, and because steel buildings are less likely to collapse than other types of vulnerable buildings.

Read more...