The Seismic Retrofit Program will be presented at the March 14, 2023 Torrance City Council Meeting.

EARTHQUAKE BRACE + BOLT PROGRAM

All Torrance ZIP codes are now eligible for the Earthquake Brace + Bolt (EBB) Program. Eligible Torrance residents can apply for grants up to $3,000 to be used to retrofit their homes to lessen the potential damage caused by earthquakes. Apply for the EBB Program today!

For questions related to the grant please contact EBB at 

Email: info@EarthquakeBraceBolt.com

Customer Service: (877) 232-4300

ACT NOW AND SAVE LATER! REGISTER HERE!

The City of Torrance is in the process of developing a Seismic Retrofit Program for commercial and multi-unit residential buildings.  In the near future, the City Council will consider adopting mandatory ordinances to require the evaluation and retrofit of specific building types proven to be vulnerable to seismic events. 

The Community Development Department, Building and Safety Division will host six workshops for building owners, though anyone is welcome to attend.  

We plan to host these Community Workshops at the Torrance Public Library - Katy Geissert Civic Center Library. Please see the events and times listed below:

What is the Seismic Retrofit Program?

The City of Torrance is located in a geographical area prone to high seismic activity due to proximity to earthquake faults in the region.  Within the City, there are older, potentially at-risk buildings that are a major concern because they were built to the design standards in place at the time of their construction.  Design standards have been updated since then, but without a mandate to retrofit these older at-risk buildings there is a high possibility they could be severely damaged during a major seismic event and could result in loss of life. Unfortunately, the City has found that it contains hundreds of buildings with the following potential seismic deficiencies:

• Wood buildings with soft/weak or open-front walls
• Buildings containing non-ductile concrete,
• Buildings with pre-Northridge steel moment frames, and
• Buildings with rigid-wall-flexible-diaphragm wall anchorage system deficiencies

These structures are considered to have one of the highest risk of significant damage during a large earthquake. To address this major concern, City Council directed staff to propose ordinances that would mandate structural retrofit of these older, at-risk buildings for their consideration. 

Existing Wood-Frame Buildings With Soft, Weak or Open-Front Walls

A wood-framed building with soft, weak or open-front walls is a multi-story wood structure where the first story is substantially weaker and more flexible than the stories above. This is typically due to lack of walls or frames at the first floor. These buildings were commonly designed prior to the 1980's and contain large open areas for tuck-under parking or commercial space, such as restaurants or convenience stores. 

Buildings with a soft-story condition are particularly vulnerable to severe damage and collapse during an earthquake. Without proper strengthening, the soft-story floor may suffer structural damage or complete failure during or after an earthquake. 

View Existing Wood-Frame Buildings with Soft, Weak, or Open-Front Walls Presentation

Non-Ductile Concrete Structures

Non-ductile concrete buildings are structures that contain brittle concrete elements (columns, beams, walls, and connections) that tend to perform poorly during earthquakes due to the limited amount of provided reinforcing steel. In a concrete building designed per today’s code standards, the reinforcing steel is designed to act as a strong cage, holding the concrete intact inside of the elements during an earthquake and allowing it to continue to support the building weight.

 In a non-ductile concrete building, typically designed using older pre-1980’s building codes, the elements have too little steel reinforcement to form a confining cage. As a result, the concrete element cracks and crushes, losing its ability to continue to support load as the concrete pieces spall or fall out of the cage. The building consequently may partially or fully collapse because of a large earthquake.

During the 1994 Northridge Earthquake in the Los Angeles area, many steel moment-resisting frame structures experienced unexpected brittle damage to their beam-to-column connections. Steel moment frames resist lateral earthquake loads primarily through bending of the beams and columns so the joint between these two elements becomes critical in their performance. Experts discovered that these buildings suffered from a wide range of flaws resulting from shortcomings in established design and construction procedures, including poor basic connection geometry, poor connection welding materials, and inadequate quality control, among other factors. Some column fractures were even observed in several buildings at the beam-to-column connections.

Many of these buildings have not been retrofitted and may be susceptible to similar severe structural damage or even building collapse in a major earthquake. Since the Northridge Earthquake, building code revisions have changed the way these buildings are designed, detailed, and the way quality control during construction is performed to ensure the steel moment frames perform as intended.

View Pre-Northridge Steel Moment Frames and Non-Ductile Concrete Presentation

Rigid-wall-flexible diaphragm buildings are buildings that consist of concrete/masonry wall with wood panelized roof system. The connection between the wall and the roof is generally weak and during a major seismic event the probability that the roof to wall interconnection will separate is high and could also result in structural failure. Buildings built prior to the 1994 Uniform Building Code are considered at-risk structures because of the lower construction standards at that time.

View Rigid Wall with Flexible Diaphragm Presentation

Should you have any questions about the City of Torrance Seismic Retrofit Program, please contact the Building and Safety Division of the Community Development Department at Seismic@TorranceCA.Gov