AWARD WINNING SEISMIC ENGINEERS

Los Angeles Ordinance 183893

LA seismic retrofit ordinance 183893
In October 2015, the Los Angeles Ordinance 183893 was adopted, intending to improve the seismic safety of the city of Los Angeles. The ordinance addresses 15,000 buildings in the city, which were built before 1978. The ordinance requires analysis of open-front, wood-framed apartment buildings as well as non-ductile concrete buildings, to show conformance with minimum earthquake standards. Non-conforming buildings must be strengthened or demolished within specified time frames.

Is the 183893 Ordinance Necessary?

In short to the question “is the 183893 Ordinance necessary? - Yes, as long as the Katrina Hurricane was the worst natural disaster ever to occur in the United States. Property damage and associated loss were estimated to be over $100 Billion dollars. Also a very large earthquake in San Francisco or Los Angeles is estimated by the USGS to result in over $200 Billion in a loss. The risk to older buildings has been well-recognized for many years. Many previous seismic strengthening programs have been implemented, such as Senate Bill 1953 affecting Acute Care Hospitals throughout California. So, if strengthening of our buildings and infrastructure are not completed, we are vulnerable to a life-changing event that could change the affected region for over 100-years.

Building Configuration and Detailing

While seismic retrofit can be expensive, the costs vary greatly depending on the specific building configuration and detailing, and the experience and expertise of the engineer and contractor. Benefits of Retrofitting include:

  • Retrofitting may be economical in the mid-term, with a pay-back period of 5-10 years due to reduced insurance premiums and increased lease rates.

  • Once the City determines that a building falls within the scope of the Ordinance, the owner is required to advise current and prospective tenants who use or occupancy the building.

  • Strengthened buildings are more attractive, and more valuable, to prospective tenants and buyers and are easier to finance and insure.

  • Strengthened buildings are much less likely to suffer damage in any size earthquake, and will, therefore, be more likely to be green-tagged after an event. This preserves rental income for the owner.

Non-Ductile Concrete Buildings

Non-ductile concrete buildings are considered dangerous for two main reasons:

  • Most of them were built before 1978

  • The concrete used in their frames has become brittle over time and it is at risk of cracking and collapsing during any seismic activity.

The floors and roofs of most of these buildings have made of concrete that is only supported by the concrete walls. There is a big chance, in case any of the floor or walls crack, the structure can completely and quickly collapse. Unfortunately, non-ductile concrete buildings are built across the world and they are considered to be the most dangerous structures which lead to more fatalities during an earthquake, than any other.
When the city of Los Angeles presented its mandatory seismic retrofit program, most of the non-ductile concrete structures were involved. Over thousands of these types of buildings are located all around the city - those are the buildings that most likely can collapse on themselves in an earthquake event. Retrofit contractors are needed to make the target structures safer and more resistant to seismic activities.

Los Angeles seismic retrofit program has become quite advanced in its fourth year. The estimates have done recently, show that only 14% of the soft-story retrofits have been performed - but sadly, 0% of the non-ductile concrete retrofits have been started, although the retrofit deadline for these types of buildings is further out than the other soft-story buildings.

block sinking into ground

Non-Ductile Concrete Retrofit Program

The city of Los Angeles Department of Building and Safety has designed the Non-Ductile Concrete Retrofit Program aiming to help reduce injury or loss of life from the effects of an earthquake on non-ductile concrete properties and structures. The recent earthquakes all over the world have shown the weakness of such kind of structures and the devastating loss of lives because of them. In California, non-ductile concrete buildings that were constructed prior to the Los Angeles City Buildings Code provisions are at risk of collapse and pose notable life safety hazards.
The non-ductile concrete retrofit program provides a guide for property owners to meet the less standard in improving the performance of these kinds of structures.

Requirements for Non-Ductile Concrete Buildings

  • The City may not serve notices to Owners of Non-Ductile Concrete (NDC) buildings until 2017.

  • The Ordinance affects buildings of concrete-frame construction with non-ductile detailing of steel reinforcing bars, permitted prior to January 13, 1977. These buildings are typical of multi-family residential or office occupancy, or parking structures.

  • A Structural Checklist must be submitted within three-years after service of the Notice.

  • Unless the building is shown to NOT fall within the Ordinance Jurisdiction, owners have ten-years to submit plans to the Building Department for strengthening the building or for demolition.

  • Retrofit (or demolition) must be completed within 25-years of the Notice.

Soft-Story Retrofit Design

Before any construction begins, the soft-story retrofit design has to be submitted to the city for approval, and application for a work permit must be filed. In general, it takes about a month for both of these to be approved. If you are a landlord and you have landlords in your property, you will also need to fill out then submit a Tenant Habitability Plan and file it with the LA Housing and Community Investment Department.

If a Tenant Habitability is needed, you can not start any construction until two months after it is served to your tenants. Tenants will get 15 days from the day of service to appeal to anything in the plan they do not agree with. Sometime, tenants may have to be temporarily relocated before construction starts, depending on the scope of the retrofit works.