Earthquake Disaster Illustrates importance of L.A. County’s Nonductile Concrete Building Seismic Ret

Earthquake Disaster Illustrates importance of L.A. County’s Nonductile Concrete Building Seismic Retrofitting Law

Is your building receiving an order to comply? Here’s what you need to know.

By Ali Sahabi, Chief Operating Officer, Optimum Seismic, Inc.

We were all shaken by reports of February’s earthquake disaster in Turkey and Syria.  Nearly 50,000 were confirmed dead, and at least 164,000 buildings collapsed or were so badly damaged they need to be demolished. From the comfort of our homes, it’s easy to think we are immune to such catastrophes. Yet, many of those fallen buildings shared the same life-threatening construction flaw that many others do in and around Los Angeles.

These multistory, nonductile concrete structures line many of our streets, providing space for offices, apartments, condos, hotels and other uses. Comprised of concrete floors and/or roofs supported by concrete walls, columns and/or frames, these buildings are extremely rigid and – unlike wood and steel – are unable to bend to absorb the forces of a seismic event. Since these structures also lack steel reinforcement necessary to hold them up during an earthquake, their concrete columns become brittle, break, and in many instances collapse.

We’ve experienced local disasters due to these building weaknesses in the 1971 Sylmar and 1994 Northridge earthquakes. The 6.5 magnitude Sylmar quake shook the foothills of the San Gabriel Mountains with such ferocity that portions of the Olive View Medical Center and Veterans Hospital collapsed, killing dozens of people. The severity of that tragedy led to the Hospital Safety Act of 1972, requiring the geological and seismological factors be designed into all new construction and/or retrofits of existing vulnerable facilities.

The Northridge earthquake was another striking reminder of the hazards inherent in these nonductile concrete structures. Jarring images from that earthquake – showing grotesquely twisted parking structures, collapsed freeway overpasses, and the Northridge Meadows apartment collapse portray isolated instances of the devastation. But the overall impact was even more startling. More than 112,000 structures were damaged, with 93,000 requiring inspection and roughly 2,000 condemned, according to the California Seismic Safety Commission.  Overall, the earthquake caused $20 billion in losses (nearly $40.5 billion in today’s dollars), and 25,000 dwelling units were lost or severely damaged.

Mandatory Earthquake Retrofit Law

Eric Garcetti, as mayor of Los Angeles, in 2015 pushed for the nation’s most sweeping earthquake retrofit laws, requiring seismic fortification of pre-1977 non-ductile concrete structures, as well as pre-1978 wood-framed soft-story buildings. Specifically, the nonductile concrete retrofit law applies to buildings with concrete floors or roofs, with or without beams, supported by concrete columns and/or concrete frames with or without masonry infills. The city began identifying and notifying owners of the 1,337 vulnerable buildings several years ago. Those that receive an order to comply with the retrofit law have 25 years to comply, based on the following milestones, which kick in from the date of the Order to Comply:

• 3 Years: Submit a completed checklist and supporting documentation
• 10 Years: Submit either (1) proof of a previous retrofit; (2) a structural analysis and detailed plans showing full compliance with the law; or (3) plans to either retrofit or demolish the building.
• 25 Years: Complete retrofit construction and obtain a Certificate of Compliance.

What’s the Progress So Far?

City officials estimate there are 1,337 nonductile concrete buildings in need of retrofits. According to the most recent compliance report available online, dated July, 2021, only 243 (18.2%) have completed the initial step of submitting a checklist completed by a certified engineer. Another 47 (3.5%) have completed the 10 year deadline of providing proof of a previous retrofit, a structural analysis and plans showing full compliance with the law, or plans to retrofit or demolish the building. Only 2 buildings (less than 1%) have complied with the ordinance and received their Certificate of Compliance indicating that their building is safe.

Widespread earthquake resilience can be best achieved with a focus on the thousands of buildings in many major cities that are at risk of collapse in a major earthquake. Each of these buildings represents hundreds, if not thousands of lives and livelihoods: tenants, employees, customers, students, health care workers and patients, and the list goes on. The average age of a commercial building in the United States is about 50 years. Mixed-use development is about 75 years old on average. These structures were constructed in the 1950s to 1970s, and most of them are vulnerable to damage if in an earthquake prone region.

Mitigating the problems with these structures can provide a high return on investment because of the potential to save lives and, when coupled with other upgrades, it can add to the life of a building and increase its value. The National Institute of Building Sciences found that retrofitting existing soft-story residential building stock can produce up to $16 dollars in benefit for every dollar spent. If you received a notice from the city and are wondering about your options, contact Optimum Seismic at (323) 605-0000 to arrange a consultation to examine your options.

Recently appointed to Los Angeles Mayor Karen Bass’ transition team, Ali Sahabi, a licensed General Engineering Contractor (GEC), is an expert in seismic resilience and sustainability. He is Co-Founder and Chief Operating Officer of Optimum Seismic, Inc., which has completed more than 3,500 seismic retrofit and adaptive reuse projects for multifamily residential, commercial, and industrial buildings throughout California.