Earthquakes have always been a concern for Californians. Over 10,000 earthquakes occur a year in California; While more than 70 percent of the state's population resides within 30 miles of a fault. The danger is equally familiar; Northridge (1994), Loma Prieta (1989), and San Fernando (1971), are just a few recent occurrences with devastating effects.
Concern reached an all-time high in 2013 when the USGC (United States Geological Center) survey offered new insight into the danger. Officials took notice, Enacting both California State Laws and California Health and Safety Code Sections 19101 and 19162-63.6. These Codes both authorized and encouraged local jurisdictions to establish mandatory seismic retrofit standards.
What is a Seismic Ordinance?
A seismic ordinance is a law passed by local authorities requiring the evaluation and retrofit of specific building types proven to be vulnerable to seismic events. These ordinances were created in response to poor performance of certain types of structures during previous earthquakes. These ordinances outline minimum requirements for mandatory evaluation and structural improvements intended to reduce earthquake-induced damage to classes of buildings identified to be particularly vulnerable to earthquake damage. These ordinances are generally not intended to strengthen buildings to a level of seismic performance equivalent to that of a new building designed using current building code requirements. Rather, these requirements address critical safety concerns by increasing the likelihood that occupants are able to safely exit the building in the event of an earthquake.
Where are Seismic Ordinances?
With Both California Health and Safety Code Sections 19101 and 19162-63.6 Authorizing And Encouraging Local Jurisdiction To Establish Their Own Mandatory Ordinance. Cities across California rushed to implement programs requiring buildings to be seismically retrofitted in an immediate timeline.
What Types of Buildings are Required?
A soft-story building is a structure which has a weaker first floor and is unable to carry the weight of the stories above during an earthquake. The first floor generally would have large openings in the perimeter walls such as garages, tuck under parking (parking beneath the 2nd floor) or even large windows. These buildings have been deemed extremely vulnerable to devastating damage from earthquakes and require immediate seismic retrofit.
A non-ductile reinforced concrete building is defined as having a) concrete floors and/or b) concrete roofs (either with or without beams) c) supported by concrete walls and/or d) concrete without masonry infills, or any combination thereof; and e) Built pursuant to a permit application for a new building that was submitted before 1977. These buildings have also been deemed extremely vulnerable to devastating damage from earthquakes and require immediate seismic retrofit.
Unreinforced Masonry (U.R.M.)
Unreinforced Masonry Buildings are defined as having load bearing walls, non-load bearing walls or other structures (such as chimneys) made of brick, cinderblock, tiles, adobe or other masonry material, that is not braced by reinforcing material (such as rebar in a concrete or cinder block.) Often seen in historic buildings, they are the most susceptible to earthquake damage.
Concrete - Tilt Up
Concrete Tilt-Up Buildings Have Limited/Weak Connections At The Roof To The Walls And Continuity Ties. Pre-Fabricated Concrete Slabs Are Lifted Into Place By Cranes, Then Attached To A Panelized Wood Roof, Often With Inadequate Connections. Because of the heavy concrete walls, in the event of an earthquake, these walls want to pull apart from the roof. Commonly Used In Commercial And Industrial Buildings, Concrete Tilt-Up Are Considered Extremely Vulnerable To Seismic Damage and are considered very vulnerable to seismic damage.
Building Requirements Per City
|Soft Story||Non-Ductile Concrete||Unreinforced Masonry||Tilt Up|
How Long Do I Have To Comply?
Each City Has Developed Their Own Timeline For Completion Based On The Fastest Allowable Time For Work To Be Completed. While each city has an independent timeline for completion, we recommend starting immediately. City guidelines were determined based off the MINIMUM allowable time for completion. Officials realize earthquake damage is both unpredictable and inevitable. These mandatory ordinances are not created to prevent future building vulnerabilities, but to remedy buildings that are CURRENTLY VULNERABLE.