Chapter 1 - Hazard Mitigation Web Portal - State of California

State of California Multi‐Hazard Mitigation PlanChapter 5 – Earthquakes, Floods and Wildfires: Risks and Strategiesthroughout the state to determine how many pre‐1976 non‐ductile concrete buildings they mayhave within their jurisdictions. The goal is to create an inventory so that appropriate state andlocal policy can be formulated.The most current retrofit provisions are available in ASCE 41‐06 and Appendix Chapter A5 of theInternational Existing Building Code. The following jurisdictions have retrofit programs for nonductileconcrete buildings:Table 5.J: Mitigation of Older Concrete BuildingsJurisdiction Buildings Type of ProgramLong Beach Non‐bearing URM, including non‐ductile concrete with URM Mandatory RetrofitLos Angeles 1500 to 2000 buildings Voluntary StrengtheningFremont City Hall Voluntary StrengtheningPalo Alto 49 buildings Voluntary StrengtheningPetaluma 5 buildings Partial StrengtheningSanta Monica 70 buildings Mandatory RetrofitaSource: California Seismic Safety CommissionRepair of Steel‐Frame BuildingsAfter the Northridge Earthquake, the City of Los Angeles enacted an ordinance that required therepair of existing damaged steel‐frame buildings. Many of these buildings were restored to theirpre‐earthquake conditions and are likely to suffer similar or worse damage in futureearthquakes. Elsewhere in the state no surveys of such buildings exist, although several similarlydamaged buildings were discovered in the Bay Area years after the 1989 Loma PrietaEarthquake. The state has since changed its building code for constructing new buildings withthis type of framing. There are no efforts in the state to require retrofits or enact post‐disasterrepair provisions.Mitigation of Steel‐Frame BuildingsThe cities of Los Angeles and Santa Monica have post‐earthquake repair ordinances. Los Angelesrequired owners to remove the finishes from joints in 242 buildings and repair the ones thatwere cracked. The most current recommended evaluation and retrofit provisions are in AISC 41‐06, FEMA 350 to FEMA 353 and the American Institute of Steel Construction Seismic Provisions(AISC 341). See www.aisc.org for more information. As of February 2006, the City of Los Angeleshas reported cracks repaired in welds in 500 buildings in the region of strongest NorthridgeEarthquake shaking.High‐Rise BuildingsThere is no statewide inventory of high‐rise buildings. Only approximately 0.03 percent of allbuildings in the state have eight or more stories. However, much of California’s corporate,finance, legal, and insurance commerce takes place in these buildings. The potential for loss ofmarket share in the economy from the closure of these buildings after earthquakes due tononstructural damage is significant. The Council on Tall Buildings and Urban Habitat maintainsan inventory of high‐rise buildings at www.ctbuh.org.Public Comment Draft – July 2010 163