California Cities Serious About Preparing Buildings For Earthquakes

California Cities Serious About Preparing Buildings For Earthquakes

By | 2018-01-24T01:18:06+00:00 February 1st, 2017|Earthquake Protection, Earthquake Retrofits|

seismic retrofit blogJust one year ago, the city of Los Angeles began to roll out its new earthquake retrofit laws, considered at the time to be the nation’s most comprehensive ordinances on the books.

Today, many other cities are adopting ordinances of their own – some even more stringent than those adopted by L.A.

What did last year tell us? California cities are serious about preparing for the next major quake.

In Southern California alone, there may be as many as 100,000 buildings facing mandates similar to those in Los Angeles as other jurisdictions begin implementing retrofit laws of their own, according to the Structural Engineers Association of California. Already, Los Angeles County, West Hollywood, Santa Monica, Beverly Hills and many other cities are in the process of adopting ordinances requiring earthquake retrofits of certain buildings. Many Northern California cities are doing the same.

How Has the Law Impacted L.A.?

Of the 13,500 buildings identified as needing a retrofit, there have been approximately 1,200 engineering plans submitted to the city, according to officials with the Los Angeles Department of Building and Safety. Approximately 125 building retrofits have been completed.

At first glance these numbers may seem low, but it’s important to recognize that this is a lengthy process requiring multiple steps and reviews before construction can begin. The property owners who have already started in on getting their retrofits done recognize that the process for getting plans approved by the city will become increasingly slow, log-jammed undertaking as others start rushing in haste to get their applications in before the deadline.

Secondly, the city’s notices to comply are still going out to property owners affected by the new laws. That means that not everyone has been contacted of their need to get a seismic retrofit. Owners of pre-1978 wood-framed soft-story buildings have two years from the date they receive their notice to submit engineering plans to the city. Owners of applicable non-ductile structures have three years from the receipt of their notice to submit a completed checklist for review.

The Building Department has published a list of all softstory buildings and has an online search tool or mobile app (LADBS Go App) where you can confirm whether your building might be tagged for a retrofit.

Why Does the Process Take So Long?

The good news is that the City of Los Angeles has set up a special unit to oversee and manage the retrofit process from start to finish. That ensures that the people inspecting a property owner’s plans are knowledgeable about structural engineering as it relates to seismic activity, which helps to ensure that work will be done right.

City officials are clearly interested in making Los Angeles safer for everyone in the event of an earthquake. They are serious about avoiding the death, injury and displacement of residents should a structure fail the next time seismic activity shakes the region in a big way.

Hazardous materials testing required of all buildings before work can begin, is another aspect of this broader issue of public safety.

Another requirement, mandating the completion of a Tenant Habitability Plan, can also complicate and slow down the process, but this is also an important check put in place by the city to ensure that residents are not unduly disrupted during the retrofit process.

The City of Los Angeles Housing and Community Investment Department says tenants can remain in their home so long as the construction work does not make the home uninhabitable outside of construction hours and will not expose tenants at any time to toxic or hazardous materials.

A lot of soft-story building owners we speak with express concern over this process out of fear that they may need to pay to relocate their tenants while construction takes place. We have found that property engineering design and a tenant-friendly construction schedule can get the work done without the need for relocation, and with very little impact on the tenants at all.

Every Building is Different

It’s important to note that there is no one-size-fits-all approach to seismic retrofitting. In fact, there is a lot of science that goes into the process.

Even though two structures may look identical from the outside, each has its unique conditions – based on the overall structure of the building, the materials used to build it, the placement of windows and doors, even the soil beneath the structure can impact how a building reacts during an earthquake.

In the case of a soft-story structure, with open parking on the ground floor and units built above it, earthquake damage or building failure typically happens when the structure starts to sway as the result of the movement of the ground below. Many factors play into this and all must to be included as a part of the engineering report submitted to the city.

For most soft-story structures, the installation of steel frames helps to prevent the excessive swaying that can lead to building collapse. Where to place the frame and how many of them to use are subject to the unique distinctions of each individual building.

Optimum Seismic has its own steel fabrication facility to carefully prepare customized frames designed uniquely for the specifications of each building that we retrofit. The frames are installed not for weight-bearing support, but to stabilize the building during an earthquake. It’s important that the frames themselves be somewhat flexible. Strategic location of frames can enhance its ability to absorb some of the shock of the earthquake to minimize damage.

The University of California at San Diego, home to the world’s largest outdoor shake table, has done repeated tests replicating the effects of a quake on a variety of structures. They recently conducted experiments on the performance of soft-story structures – buildings constructed over ground-level parking – and found that retrofits are quite effective in helping to control or even prevent damage.

You can find several videos about earthquake retrofits by searching online.

About the Author:

Ali Sahabi
Ali Sahabi has been a licensed General Engineering Contractor (GEC) since 1993, and is a principal at Optimum Seismic, Inc. He has completed hundreds of seismic retrofitting and adaptive reuse projects for multifamily residential, commercial, and industrial buildings throughout California.

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