Deadly building flaw common in California brings destruction, misery

As seismic engineers study the earthquakes in Turkey and Syria that killed more than 20,000 people this week, it's becoming clear that a significant cause of the destruction involved a building design common in California and other parts of the U.S.

The flaws of non-ductile concrete construction are found across the Golden State, with many buildings having not been evaluated or retrofitted and at risk of collapse in a serious earthquake.

It can be tempting for Californians to assume that their structures are inherently better than those in Turkey.

But the state hasn't been tested with a magnitude 7.8 earthquake in more than a century. And that event — the great 1906 earthquake — destroyed much of San Francisco.

It will take time for structural engineers to compile a comprehensive report on the damaged and destroyed buildings in Turkey and Syria.

But several experts, looking at photos and videos of the pancaked structures, said the primary flaw is already obvious: They were non-ductile concrete buildings, which have an inadequate configuration of steel reinforcing bars that allows concrete to become brittle and explode out of the structure's columns when shaken.

“The residential apartment buildings in the area are mostly made of brittle concrete and are extremely vulnerable to the shaking caused by earthquakes,” structural engineering firm Miyamoto International said in a statement.

Concrete frame buildings were popular after World War II and line many of Los Angeles' most famous boulevards. But their lethal flaws became evident internationally during the 1971 Sylmar earthquake, which occurred 52 years ago Thursday.

In that quake, officials were stunned to find the newly built Olive View Medical Center heavily damaged. The five-story hospital lurched sideways when some of its first-floor columns broke. Three concrete stairwells toppled. A two-story psychiatric building collapsed. Three people died.

A U.S. Geological Survey simulation said it is plausible a magnitude 7.8 earthquake in Southern California could cause 50 nonductile concrete buildings to fully or partly collapse, with as many as 7,500 people in them.

“We have many thousands of them throughout California, and many tens of thousands of Californians live and work in these buildings,” said USC earth sciences professor James Dolan, an expert on California's and Turkey's fault systems. “We know they're not going to perform well in earthquakes. It's not a knowledge gap. We understand what's going to happen to them when they're shaken in large earthquakes.”

These buildings have shown vulnerabilities in quakes around the globe for half a century.