Non-ductile concrete buildings in California: Lessons from Turkey, Syria earthquakes

(MENAFN) The latest earthquakes in Turkey and Syria have raised worries about the safety of non-ductile concrete buildings in California. The widespread use of non-ductile concrete, a building material that does not have much steel reinforcement and holds up poorly in earthquake conditions, was one of the main reasons for the building collapses in Turkey and Syria. Although there are thousands of non-ductile concrete constructions in California, they are not as common as they are in Turkey, primarily because such buildings stopped being erected in the United States after a 1971 earthquake in San Fernando, CA.

Nonetheless, thousands of buildings in California were erected before 1976 when new building codes led to stricter requirements, and are built with the same material. Although it's hard to determine an exact amount of buildings, estimates range between as few as seven thousand to as many as seventeen thousand buildings in the highest-risk states. Most are residential buildings, but some are schools and government buildings.

Cities in California are actively working to retrofit non-ductile concrete buildings. The first such ordinance was introduced in Los Angeles in 2015, and other cities, including Beverly Hills, Burbank, and Santa Monica, have enacted similar ones. However, the retrofits are slow going, and it could take up to 25 years to complete the Los Angeles plan. This slow advancement is due to the high cost of retrofitting, which for many, could quickly turn into a multi-million dollar process.

Robert Kraus, a structural engineer, said early cost projections in Los Angeles estimated that it would cost about USD150 to USD200 per square foot renovated. Another issue is the invasiveness of the renovations. To retrofit non-ductile concrete, "new, stiff elements" must be placed around the older elements to limit their movement during earthquakes and reinforce them, which are fairly large elements that cannot be tucked into a closet or sneaked in too many places.

Despite the alarming number of non-ductile concrete buildings in California, there are several compounding factors that make it unlikely for a crisis of the same scale as in Turkey and Syria to occur in the United States. One major difference is the attitude towards such construction. In the United States, buildings with a "soft" or "weak" story as its ground floor are less common because of building codes, and buildings with these stories have also been retrofitted. Additionally, construction in the United States is generally better regulated and follows stricter building codes than in Turkey.

In conclusion, the recent earthquakes in Turkey and Syria have highlighted the importance of seismic retrofitting in non-ductile concrete buildings in California. Although the scope of the problem is much smaller than in Turkey, the slow progress of retrofitting and the high cost remain major obstacles. However, the proactive measures taken by California cities and the stricter building codes in the United States make it unlikely that a crisis of the same scale as in Turkey and Syria will occur.


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