The Northridge Earthquake and How it Changed LA

Posted February 6, 2020, under Blog

On January 17th, 1994, the Northridge earthquake rattled Los Angeles. The quake occurred at 4:30 AM in the San Fernando Valley, with a magnitude of 6.7.

During the same year, Los Angeles began building the Getty Center. Because of the significance of the structure to Los Angeles, structural engineers had designed the landmark beyond the minimal building codes.

“We thought the Getty had been designed for a level of earthquake demand greater than the minimum requirements in the building code—by a substantial amount,” Tom Sabol, a principal with engineering firm Englekirk Institutional said about the design (via Curbed LA).

But the Getty did not make it through the Northridge earthquake intact – a week later contractors discovered cracks in the wielding in one of the steel-framed buildings that had recently been constructed. In fact, it wasn’t just the one crack, some 80 joints were damaged, with one cracked in half, and one steel column was cracked.

This was the first time the vulnerability of steel moment frames had been exposed, much in part thanks to the large magnitude of the earthquake and the Getty’s proximity to the epicenter. Before the Northridge earthquake, engineers had thought steel moment frames to be some of the most earthquake-proof types of construction.

One month after the devastating temblor, similar types of damage were found in steel-framed buildings throughout Los Angeles – with damage occurring in “modern” buildings that had been developed in just the last five years.

“This wasn’t supposed to happen,” Nestor Iwankiw, then-president of the American Institute of Steel Construction, told the L.A. Times. “This is the first time this type of failure has been seen.”

Soon after the quake, the Getty assembled a team of structural engineers, specialists and steel manufacturers to identify the structural weaknesses in steel moment frames, tasked with the job of fixing them.

Thanks to their quick response, their research efforts motivated a larger research project sponsored by the Federal Emergency Management Agency.

Ultimately, it was the Getty’s involvement that paved the way for stronger building codes throughout the industry, requiring all new buildings to use stronger materials, higher quality wields, and more testing for any new type of connection.

As a result, Los Angeles ordered the inspections of 239 steel moment frame buildings in the county –mostly structures in West Los Angeles and the San Fernando Valley. The city likewise mandated repairs by building owners in structures that were damaged from the quake.

Still, there are many steel structures that were built before 1994 that reside outside those mandated regions that have yet to be inspected or retrofitted by Los Angeles.

While the city has mandated the retrofits of soft story and non-ductile concrete buildings, steel buildings have largely been ignored.

One of the most concerning areas is downtown Los Angeles. Because the buildings have not been inspected for damage, there’s little information on how many skyscrapers in the area have vulnerabilities or failures that just haven’t been discovered yet.

While we’ll have to wait and see what happens with the retrofitting of steel buildings in Los Angeles, you can still take the necessary precautions if you own a home in Los Angeles.

If you own an older property, seismic retrofitting is a necessary safeguard for protecting those who reside there and for maintaining the value of your home.

At Julian Construction, we’ll help you find the best solution for your seismic retrofitting needs and foundation problems.

No matter what your foundation situation is, we’ll conduct a (free) inclusive home inspection, followed by a detailed consultation, and at the end of our discussion we’ll provide you with a quote for repair.

Julian De La Torre is an expert in Los Angeles foundation inspection, foundation contractors, earthquake retrofitting, foundation repair and foundation replacement. Julian’s company, Julian Construction, has inspected over 30,000 structures, working with engineering firms and local departments of building & safety. The company has done more foundation repair and earthquake retrofitting in Los Angeles than any other company in the area over the last five years.

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