(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.