[Ord. #07-07, § 8]
This section establishes regulations as amendments to the Building
Code for the expeditious repair of damaged structures. In the event
an amendment to the California Building Standards Code results in
differences between these building standards and the California Building
Standards Code, the text of these building standards shall govern.
In accordance with California Health and Safety Code Section 17958.7,
express findings that modifications to the California Building Standards
Code are reasonably necessary because of local climatic, geological
or topographical conditions are either already on file with the California
Building Standards Commission, or will be filed prior to the effective
date of the ordinance[1] codified in this section. In accordance with California
Government Code Section 50022.6, at least one (1) true copy of the
California Building Code has been on file with the Building Official
since fifteen (15) days prior to enactment of the ordinance* codified
in this section. While this section is in force, a true copy of this
section shall be kept for public inspection in the office of the Building
Official. A reasonable supply of this section shall be available in
the office of the Building Official for public purchase.
[1]
Editor's Note: Ordinance No. 07-07, a portion of which is
codified herein as Section 12-12, was adopted December 3, 2007.
[Ord. #07-07, § 8]
For the purposes of this section, the following definition applies
and is hereby added to Section 3402.1 Definitions of the 2007 California
Building Code (CBC):
A condition where:
In any story, the vertical elements of the lateral-force-resisting
system, have suffered damage such that the lateral load-carrying capacity
of the structure in any direction has been reduced by more than 20
percent from its pre-damaged condition, or
The capacity of any vertical gravity load-carrying component,
or any group of such components, that supports more than 30 percent
of the total area of the structure's floor(s) and roof(s) has been
reduced more than 20 percent from its pre-damaged condition, and the
remaining capacity of such affected elements with respect to all dead
and live loads is less than 75 percent of that required by the building
code for new buildings of similar structure, purpose, and location.
[Ord. #07-07, § 8]
For the purposes of this section, the following repair requirements
are hereby added as a new Subsection 3403.5 to Section 3403 Additions,
Alterations or Repair in the 2007 California Building Code (CBC):
3403.5.1 Repairs. Repairs of structural elements
shall comply with this section.
3403.5.1.1 Seismic evaluation and design. Seismic
evaluation and design of an existing building and its components shall
be based on the following criteria.
3403.5.1.1.1 Evaluation and design procedures. The
seismic evaluation and design shall be based on the procedures specified
in the building code, ASCE 31 Seismic Evaluation of Existing Buildings
(for evaluation only) or ASCE 41 Seismic Rehabilitation of Existing
Buildings. The procedures contained in Appendix A of the International
Existing Building Code shall be permitted to be used as specified
in Section 3403.5.1.1.3.
3403.5.1.1.2 CBC level seismic forces. When seismic
forces are required to meet the building code level, they shall be
one of the following
1.
100 percent of the values in the building code. The R factor used
for analysis in accordance with Chapter 16 of the building code shall
be the R factor specified for structural systems classified as "Ordinary"
unless it can be demonstrated that the structural system satisfies
the proportioning and detailing requirements for systems classified
as "Intermediate" or "Special".
2.
Forces corresponding to BSE-1 and BSE-2 Earthquake Hazard Levels
defined in ASCE 41. Where ASCE 41 is used, the corresponding performance
levels shall be those shown in Table 3403.5.1.1.2.
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TABLE 3403.5.1.1.2
ASCE 41 and ASCE 31 PERFORMANCE LEVELS a
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OCCUPANCY CATEGORY (BASED ON IBC) TABLE 1604.5)
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PERFORMANCE LEVEL FOR USE WITH ASCE 31 AND WITH ASCE 41 BSE-1
EARTHQUAKE HAZARD LEVEL
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PERFORMANCE LEVEL FOR USE WITH ASCE 41 BSE-2 EARTHQUAKE HAZARD
LEVEL
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I
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Life Safety (LS)
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Collapse Prevention (CP)
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II
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Life Safety (LS)
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Collapse Prevention (CP)
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III
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Notea
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Notea
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IV
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Immediate Occupancy (IO)
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Life Safety (LS)
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a Performance Levels for Occupancy
Category III shall be taken as halfway between the performance levels
specified for Occupancy Category II and Occupancy Category IV.
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3403.5.1.1.3 Reduced CBC level seismic forces. When seismic forces are permitted to meet reduced building code levels,
they shall be one of the following:
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a. 75 percent of the forces prescribed in the building code.
The R factor used for analysis in accordance with Chapter 16 of the
building code shall be the R factor as specified in Section 3403.5.1.1.2.
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b. In accordance with the applicable chapters in Appendix A
of the International Existing Building Code as specified in Items
2.1 through 2.5 below. Structures or portions of structures that comply
with the requirements of the applicable chapter in Appendix A shall
be deemed to comply with the requirements for reduced building code
force levels.
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2.1.
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The seismic evaluation and design of unreinforced masonry bearing
wall buildings in Occupancy Category I or II are permitted to be based
on the procedures specified in Appendix Chapter A1.
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2.2.
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Seismic evaluation and design of the wall anchorage system in
reinforced concrete and reinforced masonry wall buildings with flexible
diaphragms in Occupancy Category I or II are permitted to be based
on the procedures specified in Appendix Chapter A2.
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2.3.
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Seismic evaluation and design of cripple walls and sill plate
anchorage in residential buildings of light-frame wood construction
in Occupancy Category I or II are permitted to be based on the procedures
specified in Appendix Chapter A3.
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2.4.
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Seismic evaluation and design of soft, weak, or open-front wall
conditions in multiunit residential buildings of wood construction
in Occupancy Category I or II are permitted to be based on the procedures
specified in Appendix Chapter A4.
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2.5.
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Seismic evaluation and design of concrete buildings and concrete
with masonry infill buildings in all Occupancy Categories are permitted
to be based on the procedures specified in Appendix Chapter A5.
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3.
In accordance with ASCE 31 based on the applicable performance level
as shown in Table 3403.5.1.1.2.
4.
Those associated with the BSE-1 Earthquake Hazard Level defined in
ASCE 41 and the performance level as shown in Table 3403.5.1.1.2.
Where ASCE 41 is used, the design spectral response acceleration parameters
Sxs and Sx1 shall not be taken less than 75 percent of the respective
design spectral response acceleration parameters SDS and SD1 defined
by the International Building Code and its reference standards.
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3403.5.1.2 Wind Design. Wind design of existing
buildings shall be based on the procedures specified in the building
code.
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3403.5.2 Repairs to damaged buildings. Repairs
to damaged buildings shall comply with this section.
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3403.5.2.1 Unsafe conditions. Regardless of the
extent of structural damage, unsafe conditions shall be eliminated.
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3403.5.2.2 Substantial structural damage to vertical elements
of the lateral—force-resisting system. A building that
has sustained substantial structural damage to the vertical elements
of its lateral-force-resisting system shall be evaluated and repaired
in accordance with the applicable provisions of Section 3403.5.2.2.1
through 3403.5.2.2.3.
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3403.5.2.2.1 Evaluation. The building
shall be evaluated by a registered design professional, and the evaluation
findings shall be submitted to the code official. The evaluation shall
establish whether the damaged building, if repaired to its pre-damage
state, would comply with the provisions of the building code. Wind
forces for this evaluation shall be those prescribed in the building
code. Seismic forces for this evaluation are permitted to be the reduced
level seismic forces specified in Code Section 3403.5.1.1.3.
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3403.5.2.2.2 Extent of repair for compliant
buildings. If the evaluation establishes compliance of the
pre-damage building in accordance with Section 3403.5.2.2.1, then
repairs shall be permitted that restore the building to its pre-damage
state, using materials and strengths that existed prior to the damage.
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3403.5.2.2.3 Extent of repair for non-compliant
buildings. If the evaluation does not establish compliance
of the pre-damage building in accordance with Section 3403.5.2.2.1,
then the building shall be rehabilitated to comply with applicable
provisions of the building code for load combinations including wind
or seismic forces. The wind design level for the repair shall be as
required by the building code in effect at the time of original construction
unless the damage was caused by wind, in which case the design level
shall be as required by the code in effect at the time of original
construction or as required by the building code, whichever is greater.
Seismic forces for this rehabilitation design shall be those required
for the design of the pre-damaged building, but not less than the
reduced level seismic forces specified in Section 3403.5.1.1.3. New
structural members and connections required by this rehabilitation
design shall comply with the detailing provisions of the building
code for new buildings of similar structure, purpose, and location
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3403.5.2.3 Substantial structural damage to vertical load-carrying
components. Vertical load-carrying components that have sustained
substantial structural damage shall be rehabilitated to comply with
the applicable provisions for dead and live loads in the building
code. Undamaged vertical load-carrying components that receive dead
or live loads from rehabilitated components shall also be rehabilitated
to carry the design loads of the rehabilitation design. New structural
members and connections required by this rehabilitation design shall
comply with the detailing provisions of the building code for new
buildings of similar structure, purpose, and location.
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3403.5.2.3.1 Lateral force-resisting elements. Regardless
of the level of damage to vertical elements of the lateral force-resisting
system, if substantial structural damage to vertical load-carrying
components was caused primarily by wind or seismic effects, then the
building shall be evaluated in accordance with Section 3403.5.2.2.1
and, if non-compliant, rehabilitated in accordance with Section 3403.5.2.2.3.
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3403.5.2.4 Less than substantial structural damage. For damage less than substantial structural damage, repairs shall
be allowed that restore the building to its pre-damage state, using
materials and strengths that existed prior to the damage. New structural
members and connections used for this repair shall comply with the
detailing provisions of the building code for new buildings of similar
structure, purpose, and location.
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3403.5.3 Referenced Standards
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Standard Reference Number
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Title
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Referenced In Code Section Number
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ASCE 31-03
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Seismic Evaluation of Existing Buildings
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3403.5.1.1.1, TABLE 3403.5.1.1.2, 3403.5.1.1.3
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ASCE 41-06
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Seismic Rehabilitation of Existing Buildings
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3403.5.1.1.1,3403.5.1.1.2, TABLE 3403.5.1.1.2, 3403.5.1.1.3
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