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POL Government Elected Officials Auditor Griffin-Valade Charter, Code & Policies City Code & Charter Online Code & Charter Title 24 Building Regulat Chapter 24.85 Seismic Design Requirements for Existing Buildings
24.85.056 Structural Systems Damaged by an Earthquake.

(Added by Ordinance No. 178831, effective November 20, 2004.) As a result of an earthquake, the Director may determine through either an ATC 20 procedure or through subsequent discovery any structure or portion thereof to be in an unsafe condition as defined by State law. As a result of making this determination, the Director may declare the structure or portion thereof to be a public nuisance and to be repaired or rehabilitation as provided in Subsections 24.85.056 A.-C., or abated by demolition or removal in accordance with Title 29. For the purposes of this Section, an "unsafe condition" includes, but is not limited to any portion, member or appurtenance of a building that has become detached or dislodged or appears likely to fail or collapse and thereby injure persons or damage property; or any portion of a building or structure that has been damaged to the extent that the structural strength or stability of the building is substantially less than it was prior to the damaging event.
 
A. Buildings built prior to January 1, 1974 with lateral support systems that have unsafe conditions shall be repaired or improved to resist seismic forces such that the repaired lateral system conforms to the ASCE 31 improvement standard.
1. Where less than 50% of the lateral support system has been damaged, only the damaged elements must be repaired.
 
2. Where 50% or more of the lateral support system has been damaged, then the entire lateral support system must be repaired to resist seismic forces such that the repaired system conforms to the ASCE 31 improvement standard.
B. Buildings built on or after January 1, 1974 with lateral support systems that have unsafe conditions shall be repaired or improved to resist seismic forces such that the repaired lateral system conforms to the code to which the building was originally designed, but not less than that required to conform to the ASCE 31 improvement standard.
1. Where less than 50% of the lateral support system has been damaged, only the damaged elements must be repaired.
 
2. Where 50% or more of the lateral support system has been damaged, then the entire lateral support system must be repaired to resist seismic forces such that the repaired system conforms to the code to which the building was originally designed, but not less than that required to conform to the ASCE 31 improvement standard.
C. New lateral system vertical elements must be compatible with any existing lateral system elements, including foundations. In multistory buildings, the engineer shall confirm that the new lateral system vertical elements do not introduce soft or weak story seismic deficiencies, as defined by ASCE 31, where they did not previously exist, or make existing conditions more hazardous.

Title 24 Building Regulat
Chapter 24.10 Administration and Enforcement
Chapter 24.15 Definitions
Chapter 24.20 Special Inspections
Chapter 24.25 Movings of Buildings
Chapter 24.30 Home Occupations
Chapter 24.35 Historical Buildings
Chapter 24.40 Use of and Projections Over Public Streets and Property
Chapter 24.45 Parking and Driveway Surfaces
Chapter 24.50 Flood Hazard Areas
Chapter 24.51 Wildfire Hazard Zones
Chapter 24.55 Building Demolition
Chapter 24.60 Fences
Chapter 24.65 Sidewalk Vault Openings
Chapter 24.70 Clearing, Grading and Erosion Control
Chapter 24.75 Uniform Building Address System
Chapter 24.80 (Repealed)
Chapter 24.85 Seismic Design Requirements for Existing Buildings
Chapter 24.90 Manufactured Dwelling Installation and Accessory Structures, Manufactured Dwelling Parks, Recreation Parks, Recreational Park Trailer Installation and Accessory Structures
Chapter 24.95 (Repealed)