Conducting Earthquake Evaluations

Sept. 1, 2005
How vulnerable is your building to seismic hazards?

As building owners and managers, your building maintenance programs should include natural hazard assessments. Building hazard evaluations should include an assessment by structural engineers of seismic (earthquake) vulnerability and the resulting potential for loss of occupancy.

What Do You Know About Your Building(s)?
You’ll want to know how old the building is, the building’s type of construction, and what changes or alterations have occurred to the facility. The building’s age may be an indicator of potential vulnerabilities. The engineering and construction industry continually learns from actual earthquakes about what works and what doesn’t work to keep a building safe and operational. Local jurisdictions typically amend their building codes every 3 years.

Where Are the Earthquake Faults?
You should investigate the location of large earthquake faults within a 100-mile radius of your building. One source to locate known faults is here. New faults are discovered periodically, so a review of fault locations should be done every few years.

Increasing an Existing Building’s Structural Integrity
Existing buildings can be seismically retrofitted to reduce your facility’s earthquake risk, based upon vulnerabilities identified in an evaluation report. Besides structural considerations, the evaluation report can include architectural, mechanical, and electrical components, which typically incur far more earthquake damage. A plan including retrofit items, their costs, and a schedule can be established to improve a building’s expected earthquake performance.

Building Codes Don’t Mandate Retrofit, Ordinances Do.
Building codes typically don’t mandate seismic retrofit, but state and local jurisdictions may adopt/

issue man­datory ordinances to retrofit existing higher-risk buildings. One example is Un-Re­in­forced Ma­-sonry Buildings (URMs) in high-seismic areas -

some building departments have enacted ordinances that require strengthening URM buildings. Frequently, strengthening is voluntary, but may become mandatory after a nearby earthquake.

Finding Qualified Individuals
Individuals qualified to review the building’s seismic integrity can be found by checking with the Structural Engineers Association in your area, accessible on the Internet. You can also ask your local building official if he/she knows of qualified engineering firms.

Expectations for the Design Professional
Foremost, always select a structural engineer that has design experience with your type of building construction. The structural engineer should be able to identify any building gravity and seismic deficiencies based upon his/her review, and summarize in a verbal or written report. At your request, the engineer can develop drawings outlining the repairs and retrofit measures. The construction documents should be submitted to your local building department for review and approval.

Michael Cochran ([email protected]), vice president of Los Angeles-based Brian L. Cochran Associates Inc., and David Cocke ([email protected]), president of Gardena, CA-based Structural Focus, are members of the Structural Engineers Association of Southern California (SEAOSC), Whittier, CA. SEAOSC is a regional association of the Structural Engineers Association of California, Sacramento.

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