The purpose of this Article is to promote public safety and
welfare by reducing the risk of death or injury that may result from
the effects of earthquakes on unreinforced masonry bearing wall buildings
constructed prior to 1934 or any unreinforced masonry building located
in the City of Inglewood. Such buildings lave been widely recognized
for sustaining life-hazardous damage, including partial or complete
collapse during moderate to strong earthquakes.
The provisions of this Article are intended as minimum standards
for structural seismic resistance established primarily to reduce
the risk of life loss or injury. Compliance with these standards will
not necessarily prevent loss of life or injury or prevent earthquake
damage to rehabilitated buildings. This Article does not require alteration
of existing electrical, plumbing, mechanical or fire safety systems
unless they constitute a hazard to life or property.
This Article provides systematic procedures and standards or
identification and classification of unreinforced masonry bearing
wall buildings based on their present use. Priorities, time periods
and standards are also established under which these buildings are
required to be structurally analyzed and anchored. Where the analysis
finds deficiencies, this Article requires the building to be strengthened
or demolished.
Qualified Historical Buildings shall comply with the State Historical
Building Code (SHBC) established under Part 8, Title 4 of the California
Administrative Code.
(Ord. 87-33 1-5-88)
The provisions of this Article shall apply to all buildings
constructed or under construction prior to 1934 or any unreinforced
masonry building located in the City of Inglewood, which on the effective
date of the ordinance codified in this Article have unreinforced masonry
bearing walls as defined herein.
EXCEPTION: This Article shall not apply to detached one or two
family dwellings and detached apartment houses containing less than
five dwelling units and used solely for residential purposes.
(Ord. 87-33 1-5-88)
For purposes of this Article, the applicable definition in Sections
2302 and 2312 of the Uniform Building Code, 1985 Edition, shall apply.
means a masonry wall having all of the following characteristics:
(Ord. 87-33 1-5-88)
The rating classifications shown in Table No. 13-A, codified
in the Appendix at the end of this Chapter, are hereby established
and each building within the scope of this Article shall be placed
in one such rating classification by the building official. The total
occupant load of the entire building as determined by Section 3302(a)
shall be used to determine the rating classification.
EXCEPTION: For the purpose of this Article, portions of buildings
constructed to act independently when resisting seismic forces may
be placed in separate rating classifications.
(Ord. 87-33 1-5-88)
The owner of each building within the scope of this Article
shall cause a structural analysis of the building to be made by a
civil or structural engineer or architect licensed by the State of
California. If the building does not meet the minimum earthquake standards
specified in this Article, the owner shall either cause it to be structurally
altered to conform to such standards; or cause the building to be
demolished.
The owner of a building within the scope of this Article shall
comply with the requirements set forth above by submitting to the
building official for review within the stated time limits:
(1)
Within
one hundred eighty days after the service of this order, a structural
analysis, which is subject to approval by the building official, and
which shall demonstrate that the building meets the minimum requirements
of this Chapter; or
(2)
Within
one hundred eighty days after the service of the order, the structural
analysis and plans for the proposed structural alterations of the
building necessary to comply with the minimum requirements of this
Article; or
(3)
Within one hundred eighty days after service of the order, plans for the installation of wall anchors in accordance with the requirements specified in Section 11-136(3); or
(4)
Within
one hundred eighty days after the service of the order, plans for
the demolition of the building.
|
After plans are submitted and approved by the building official,
the owner shall obtain a building permit, commence and complete the
required construction or demolition within the time limits set forth
in Table No. 13-B codified in the Appendix at the end of this Chapter.
|
(Ord. 87-33 1-5-88)
(1)
Service of Order. The building official shall issue an order, as provided in Section 11-135(2), to the owner of each building within the scope of this Article in accordance with the minimum time periods for service of such orders set forth in Table No. 13-B codified in the Appendix at the end of this Chapter. The minimum time period for the service of such orders shall be measured from the effective date of the ordinance codified in this Article. Upon receipt of a written request from the owner, the building official shall order a building to comply prior to the normal service date for such building set forth in this Section.
(2)
Contents of Order. The order shall be in writing and shall be served either personally or by certified or registered mail upon the owner as shown on the last equalized assessment, and upon the person, if any, in apparent charge or control of the building. The order shall specify that the building has been determined by the building official to be within the scope of this Article and, therefore, is required to meet the minimum seismic standards of this Article. The order shall specify the rating classification of the building and shall be accompanied by a copy of Section 11-134 which sets forth the owner's alternatives and time limits for compliance.
(3)
Appeal From Order. The owner or person in charge or control of the building may appeal to (the Construction Appeals Board) the building official's initial determination that the building is within the scope of this Article. Such appeal shall be filed with the board within sixty days from the service date of the order described in Section 11-135(2). Any such appeal shall be decided by the board no later than sixty days after the date that the appeal is filed. Such appeal shall be made in writing upon appropriate forms provided thereof, by the building official and the grounds thereof shall be stated clearly and concisely. Each appeal shall be accompanied by a filing fee as set forth in the code.
Appeals or requests for slight modifications from any other
determinations, orders or actions by the building official pursuant
to this Article, shall be made in accordance with the normal appeal
procedures established in this code.
(4)
Recordation.
Within thirty days of effective date of the ordinance codified in
this Article, the building official shall file with the office of
the county recorder a certificate stating that the subject building
is within the scope of Article 13—Earthquake Hazard Reduction
in Existing Buildings. The certificate shall also state that the owner
thereof may be ordered to structurally analyze the building and to
structurally alter or demolish it where it is not found to comply
with Article 13.
If the building is found not to be within the scope of this
Article, or as a result of structural alterations or an analysis is
found to be structurally capable of resisting minimum seismic forces
required by this Article; or is demolished; the building official
shall file with the office of the county recorder a certificate terminating
the status of the subject building as being classified within the
scope of Article 13—Earthquake Hazard Reduction in Existing
Buildings.
(5)
Enforcement. If the owner or other person in charge or control of the subject building fails to comply with any order issued by the building official to this Article, within any of the time limits set forth in Section 11-134, the building official may order the entire building vacated and remain vacated until such order has been complied with. If compliance with such order has not been accomplished within ninety days after the date the building has been ordered vacated, or by such additional time as may have been granted by (the Construction Appeals Board), the building official may order demolition of the building in accordance with the Abatement of Dangerous Buildings provisions of this code.
(Ord. 87-33 1-5-88)
(1)
General.
Every structure within the scope of this Division shall be analyzed
and constructed to resist minimum total lateral seismic forces assumed
to act noncurrently in the direction of each of the main axis of the
structure in accordance with the following equation:
|
V=ZIKCSW
|
(136-1)
|
The value of IKCS need not exceed the values set forth
in Table No. 13-C based on the applicable rating classification of
the building.
(2)
Lateral Forces on Elements of Structures. Parts or portions of structures shall be analyzed and designed for lateral loads in accordance with Subsection 11-136(1) and 2312(e) of the Uniform Building Code but not less than the value from the following equation:
|
Fp= ZICp SWp
|
(136-2)
|
For the provisions of this subsection, the product of
1S need not exceed the values as set forth in Table No. 13-D codified
in the Appendix at the end of this Chapter.
EXCEPTION: Unreinforced masonry walls in buildings not having a rating classification of I may be analyzed in accordance with Section 11-137.
The value of Cp need not exceed the values set forth in Table
13-E codified in the Appendix at the end of this Chapter.
(3)
Anchorage
and Interconnection. Anchorage and interconnection of all parts, portions
and elements of the structure shall be analyzed and designed for lateral
forces in accordance with Table No. 13-E of this code codified in
the Appendix at the end of this Chapter and the equation FP=ZICpSWp
as modified by Table No. 13-D codified in the Appendix at the end
of this Chapter. Minimum anchorage of masonry walls to each floor
or roof shall resist a minimum force of two hundred pounds per linear
foot acting normal to the wall at the level of the floor or roof.
(4)
Level
of Required Repair. Alterations and repairs required to meet the provisions
of this Article shall comply with all other applicable requirements
of the Uniform Building Code unless otherwise specifically provided
for in this Article.
(5)
Required
Analysis.
(a)
General. Except as modified herein, the analysis and design relating to the structural alteration of existing structures within the scope of this Article shall be in accordance with the analysis specified in Chapter 23 of the 1985 Edition of the Uniform Building Code.
(b)
Continuous Stress Path. A complete continuous stress path from every
part or portion of the structure to the ground shall be provided for
the required horizontal forces.
(c)
Positive Connections. All parts, portions or elements of the structure
shall be interconnected by positive means.
(6)
Analysis
Procedure.
(a)
General. Stresses in materials and existing construction utilized to transfer seismic forces from the ground to parts or portions of the structure shall conform to those permitted by the Uniform Building Code and those materials and types of construction specified in Section 11-137.
(b)
Connections. Materials and connectors used for interconnection of
parts and portions of the structure shall conform to the Uniform Building
Code. Nails may be used as part of an approved connector.
(c)
Unreinforced Masonry Walls. Except as modified herein, unreinforced masonry walls shall be analyzed as specified in Section 2406, 2407 and 2408 to withstand all vertical loads as specified in Chapter 23 of the Uniform Building Code in addition to the seismic forces required by this Article. The fifty percent increase in the seismic force factor for shear walls as specified in Section 2407(h)4F of the Uniform Building Code may be omitted in the computation of seismic loads to existing shear walls.
No allowable tension stress will be permitted in unreinforced
masonry walls. Walls not capable of resisting the required design
forces specified in this Article shall be strengthened or shall be
removed and replaced.
EXCEPTIONS:
1.
Unreinforced masonry walls in buildings not classified as a Rating Classification I pursuant to Table No. 13-B codified in the Appendix at the end of this Chapter may be analyzed in accordance with Section 11-137.
2.
An unreinforced masonry wall which carried no design loads other
than its own weight may be considered as veneer if it is adequately
anchored to new supporting elements.
(7)
Combination
of Vertical and Seismic Forces.
(a)
New Materials. All new materials introduced into the structure to
meet the requirements of this Section which are subjected to combined
vertical and horizontal forces shall comply with Section 2303(f).
(b)
Existing Materials. When stresses in existing lateral forces resisting elements are due to a combination of dead loads plus live loads plus seismic loads, the allowable working stress specified in the Uniform Building Code may be increased one hundred percent. However, no increase will be permitted in the stresses allowed in Section 11-137, and the stresses in members due only to seismic and dead loads shall not exceed the values permitted by Section 2303(d) of the Uniform Building Code.
(c)
Allowable Reduction of Bending Stress by Vertical Load. In calculating
tensile fiber stress due to seismic forces required by this Article,
the maximum tensile fiber stress may be reduced by the full direct
stress due to vertical dead loads.
(Ord. 87-33 1-5-88)
(1)
General.
All material permitted by the Uniform Building Code including their
appropriate allowable stresses and those existing configuration of
materials specified herein may be utilized to meet the requirements
of this Article.
(2)
Existing
Materials.
(a)
Unreinforced Masonry Walls. Unreinforced masonry walls analyzed in
accordance with this Section may provide vertical support for roof
and floor construction and resistance to lateral loads. The facing
and backing of such walls shall be bonded so that no less than four
percent of the exposed face area is composed of solid headers extending
not less than four inches into the backing. The distance between adjacent
full-length headers shall not exceed twenty-four inches vertically
or horizontally. Where the backing consists of two or more wythes
the header shall extend not less than four inches into the most distant
wythe, or the backing wythes shall be bonded together with separate
headers whose area and spacing conform to the foregoing.
Tension stresses due to seismic forces normal to the wall may
be neglected if the walls do not exceed the height to thickness ratio
in Table No. 13-F codified in the Appendix at the end of this Chapter
and the in-plane shear stresses due to seismic loads as set forth
in Table No. 13-I codified in the Appendix at the end of this Chapter.
If the wall height-thickness ratio exceeds the specified limits, the wall may be supported by vertical bracing members designed in accordance with Section 11-136. The deflection of such bracing member at design loads shall not exceed one-tenth of the wall thickness.
EXCEPTION: The wall may be supported by flexible vertical bracing members designed in accordance with Section 11-136(2) if the deflection at design loads is not less than one-quarter nor more than one-third of the wall thickness.
All vertical bracing members shall be attached to floor and
roof construction for their design loads independently of required
wall anchors. Horizontal spacing of vertical bracing members shall
not exceed one-half the unsupported height of the wall nor ten feet.
The wall height may be measured vertically to bracing elements
other than a floor or roof. Spacing of the bracing elements and wall
anchors shall not exceed six feet. Bracing elements shall be detailed
to minimize the horizontal displacement of the wall by components
of vertical displacements of the floor or roof.
(b)
Existing Roof, Floors, Walls, Footings, and Wood Framing. Existing
materials including wood shear walls utilized in the described configuration
may be used as part of the lateral load resisting system, provided
that the stresses in these materials do not exceed the values shown
in Table No. 13-G codified in the Appendix at the end of this Chapter.
(3)
Strengthening
of Existing Materials. New materials including wood shear walls may
be utilized to strengthen portions of the existing seismic resisting
system in the described configuration provided that the stresses do
not exceed the values shown in Table No. 13-H codified in the Appendix
at the end of this Chapter.
(4)
Alternate
Materials. Alternate materials, designs and methods of construction
may be approved by the building official in accordance with the provisions
of the Uniform Building Code.
(5)
Minimum
Acceptable Quality of Existing Unreinforced Masonry Walls.
(a)
General Provisions. All unreinforced masonry walls utilized to carry
vertical loads and seismic forces parallel and perpendicular to the
wall plane shall be tested as specified in this subsection. All masonry
quality shall equal or exceed the minimum standards established herein
or shall be removed and replaced by new materials. Alternate methods
of testing may be approved by the building official. The quality of
mortar in all masonry walls shall be determined by performing in-place
shear tests or by testing eight-inch diameter cores. Alternative methods
of testing may be approved by the building official. Nothing shall
prevent pointing with mortar of all the masonry wall joints before
the tests are first made. Prior to any pointing, the mortar joints
must be raked and cleaned to remove loose and deteriorated mortar.
Mortar for pointing shall be Type S or N except that masonry cements
shall not be used. All preparation and mortar pointing shall be done
under the continuous inspection of a (Registered Deputy Building Inspector).
At the conclusion of the inspection, the inspector shall submit a
written report to the licensed engineer or architect responsible for
the seismic analysis of the building setting forth the result of the
work inspected. Such report shall be submitted to the building official
for approval as part of the structural analysis. All testing shall
be performed in accordance with the requirements specified in this
subsection by a testing agency approved by the building official.
An accurate record shall be kept of all such tests and of their locations
in the building, and these results shall be submitted to the building
official and approval as part of the structural analysis.
(b)
Number and Location of Tests. The minimum number of tests shall be
two per wall or line of wall elements resisting a common force, or
one per one thousand five hundred square feet of wall surface, with
a minimum of eight tests in any case. The exact test or core location
shall be determined at the building site by the licensed engineer
or architect responsible for the seismic analysis of the subject building.
(c)
In-Place Shear Tests. The bed joints of the outer wythe of the masonry
shall be tested in shear by laterally displacing a single brick relative
to the adjacent bricks in that wythe. The opposite head joint of the
brick to be tested shall be removed and cleaned prior to testing.
The minimum quality mortar in eighty percent of the shear tests shall
not be less than the total of thirty psi plus the axial stress in
the wall at the point of the test. The shear stress shall be based
on the gross area of both bed joints and shall be that at which movement
of the brick is first observed.
(d)
Core Tests. A minimum number of mortar test specimens equal to the
number of required cores shall be prepared from the cores and tested
as specified herein. The mortar joint of the outer wythe of the masonry
core shall be tested in shear by placing the circular core section
in a compression testing machine with the mortar bed joint rotated
fifteen degrees from the axis of the applied load. The mortar joint
tested in shear shall have an average ultimate stress of twenty psi
based on the gross area. The average shall be obtained from the total
number of cores made. If test specimens cannot be made from cores
taken, then the shear value shall be reported as zero.
(6)
Testing
of Shear Bolts. One-fourth of all new shear bolts and dowels embedded
in unreinforced masonry walls shall be tested by a Special Inspector
using a torque calibrated wrench to the following minimum torques:
|
1/2" diameter bolts or dowels = 40 foot-lbs.
|
|
5/8" diameter bolts or dowels = 50 foot-lbs.
|
|
3/4" diameter bolts or dowels = 60 foot-lbs.
|
No bolts exceeding three-fourths inch shall be used.
All nuts shall be installed over malleable iron or plate washers when
bearing on wood and heavy cut washers when bearing on steel.
(7)
Determination
of Allowable Stresses for Design Methods Based on Test Results.
(a)
Design Shear values. Design seismic in-place shear stresses shall be substantiated by tests performed as specified in Section 11-137(5) c and d.
Design stresses shall be related to test results obtained in
accordance with Table No. 13-I codified in the Appendix at the end
of this Chapter. Intermediate values between three and ten psi may
be interpolated.
(b)
Design Compression and Tension Values. Compression stresses for unreinforced
masonry having a minimum design shear value of three psi shall not
exceed one hundred psi. Design tension values for unreinforced masonry
shall not be permitted.
(8)
Five
percent of the existing rod anchors utilized as all or part of the
required wall anchors shall be tested in pullout by an approved testing
laboratory. The minimum number tested shall be four per floor, with
two tests at walls with joists framing into the wall and two tests
at walls with joists parallel to the wall. The test apparatus shall
be supported on the masonry wall at a minimum distance of the wall
thickness from the anchor tested. The rod anchor shall be given a
preload of three hundred lbs. prior to establishing a datum for recording
elongation. The tension test load reported shall be recorded at one-eighth
inch relative movement of the anchor and the adjacent masonry surface.
Results of all tests shall be reported. The report shall include the
test results as related to the wall thickness and joist orientation.
The allowable resistance value of the existing anchors shall be forty
percent of the average of those tested anchors having the same wall
thickness and joist orientation.
(9)
Qualification
tests for devices used for wall anchorage shall be tested with the
entire tension load carried on the enlarged head at the exterior face
of the wall. Bond on the part of the device between the enlarged head
and the interior wall face shall be eliminated for the qualification
tests. The resistance value assigned the device shall be twenty percent
of the average of the ultimate loads.
(Ord. 87-33 1-5-88)
(1)
General.
In addition to the seismic analysis required elsewhere in this Article,
the licensed engineer or architect responsible for the seismic analysis
of the building shall determine and record the information required
by this Section on the approved plans.
(2)
Construction
Details. The following requirements with appropriate construction
details shall be made part of the approved plans:
(a)
All unreinforced masonry walls shall be anchored at the roof level
by tension bolts through the wall as specified in Table 13-H, codified
in the Appendix at the end of this Chapter or by approved equivalent
at a maximum anchor spacing of six feet.
All unreinforced masonry walls shall be anchored at all floors with tension bolts through the wall or by existing rod anchors at the maximum anchor spacing of six feet. All existing rod anchors shall be secured to the joists to develop the required forces. The building official may require testing to verify the adequacy of the embedded ends of existing rod anchors. Tests when required shall conform to Section 11-137(8).
When access to the exterior face of the masonry wall is prevented
to proximity of an existing building, wall anchors conforming to Items
5 and 6 in Table 13-H, codified in the Appendix at the end of this
Chapter, may be used.
Alternative devices to be used in lieu of tension bolts for masonry wall anchorage shall be tested as specified in Section 11-137(9).
(b)
Diaphragm chord stresses of horizontal diaphragms shall be developed
in existing materials or by adding of new materials.
(c)
Where trusses and beams other than rafters or joists are supported
on masonry, ledgers or columns shall be installed to support vertical
loads of the roof or floor members.
(d)
Parapets and exterior wall appendages not capable of resisting the
forces specified in this Article shall be removed, stabilized or braced
to insure that the parapets and appendages remain in their original
position.
(e)
All deteriorated mortar joints in unreinforced masonry walls shall
be pointed with Type S or N mortar (masonry cement shall not be used).
Prior to any pointing, the wall surface shall be raked and cleaned
to remove loose and deteriorated mortar. All preparation and pointing
shall be done under the continuous inspection of a special inspector
certified to inspect masonry or concrete. At the conclusion of the
project, the inspector shall submit a written report to the building
official setting forth the portion of work inspected.
(f)
Repair details shall be prepared for any cracked or damaged unreinforced
masonry wall required to resist forces specified in this Article.
(3)
Existing
Construction. The following existing construction information shall
be made part of the approved plans:
(a)
The type and dimensions of existing walls and the size and spacing
of floor and roof members.
(b)
The extent and type of existing wall anchorage to floors and roof.
(c)
The extent and type of parapet corrections, if any, which were performed
in accordance with the Uniform Building Code.
(d)
Accurately dimensioned floor plans and masonry wall elevations showing
dimensioned openings, piers, wall thickness and heights.
(e)
The location of cracks or damaged portions of unreinforced masonry
walls requiring repairs.
(f)
The type of interior wall surfaces and whether reinstalling or anchoring
of ceiling plaster is necessary.
(g)
The general condition of the mortar joints and whether the joints
need pointing.
|
TABLE NO. 13-A
RATING CLASSIFICATIONS TYPE OF BUILDING CLASSIFICATION
| |
|---|---|
|
Highest Priority
|
I
|
|
High Risk Building
|
II
|
|
Medium Risk Building
|
III
|
|
Low Risk Building
|
IV
|
|
Lowest Priority
|
V
|
|
TABLE 13-B
SERVICE PRIORITIES, TIME TABLE FOR COMPLIANCE WITH THE ORDINANCE
CODIFIED IN THIS APPENDIX
| |||||||||
|---|---|---|---|---|---|---|---|---|---|
|
* All times shown are calculated consecutively.
* Time of service shall be from effective day of ordinance.
| |||||||||
|
Rating
Classification
|
Occupant
Load
|
Minimum Time
For Service
of Order
|
Submittal of
Plans to
Building and
Safety
|
Option No. 1:
Full Compliance
Achieved in One Phase
|
Option No. 2:
Full Compliance in Two Phases:
| ||||
|
1. Wall Anchor
|
2. Remainder
| ||||||||
|
Obtain
Building
Permit
|
Completion
of
Construction
|
Obtain
Building
Permit
|
Completion
of
Construction
|
Obtain
Building
Permit For
Remainder
|
Completion
of
Construction
| ||||
|
I
(Highest Priority)
|
201 or more
|
90 days
|
180 days
|
180 days
|
Two years
|
180 days
|
180 days
|
Three years
|
Two years
|
|
II
|
151—200
|
One year
|
180 days
|
180 days
|
Two years
|
180 days
|
180 days
|
Three years
|
Two years
|
|
III
|
101—150
|
Two years
|
180 days
|
180 days
|
Two years
|
180 days
|
180 days
|
Four years
|
Two years
|
|
IV
|
51—100 Incl.
|
Three years
|
180 days
|
180 days
|
Two years
|
180 days
|
180 days
|
Four years
|
Two years
|
|
V
(Lowest Priority)
|
50 and below
|
Four years
|
180 days
|
180 days
|
Two years
|
180 days
|
180 days
|
Five years
|
Two years
|
|
TABLE NO. 13-C
HORIZONTAL FORCE FACTORS BASED ON RATING CLASSIFICATION
| |
|---|---|
|
RATING CLASSIFICATION
|
IKCS
|
|
I
|
0.133
|
|
II, III, IV and V
|
0.100
|
|
TABLE NO. 13-D
HORIZONTAL FORCE FACTORS "IS" FOR PARTS OR PORTIONS OF STRUCTURES
| |
|---|---|
|
RATING CLASSIFICATION
|
IS
|
|
I
|
1.00
|
|
II, III, IV and V
|
0.75
|
|
TABLE NO. 13-E
HORIZONTAL FORCE FACTOR "Cp" FOR PARTS OR PORTIONS OF BUILDINGS
OR OTHER STRUCTURES1
| ||
|---|---|---|
|
Part or Portion of Buildings
|
Direction of Force
|
Value of Cp
|
|
Exterior bearing and nonbearing walls, interior bearing walls
and partitions, interior nonbearing walls and partitions over ten
feet in height, masonry fences over six feet in height.
|
Normal to Flat Surface
|
0.20
|
|
Cantilever parapet and other cantilever walls, except
|
Normal to Flat Surface
|
1.00 retaining walls.
|
|
Exterior and interior ornamentations and appendages.
|
Any Direction
|
1.00
|
|
When connected to or a part of a building; towers, tanks, towers
and tanks plus contents, racks over 8 feet 3 inches in height plus
contents, chimneys, smokestacks, and penthouses.
|
Any Direction
|
0.202,4
|
|
When connected to or a part of a building: Rigid and rigidly
mounted equipment and machinery not required for continued operation
of essential occupancies.5
|
Any Horizontal Direction
|
0.203
|
|
Tanks plus effective contents resting on the ground.
|
Any Direction
|
0.12
|
|
Floors and roofs acting as diaphragms.
|
In the plane of the diaphragm
|
0.126
|
|
Prefabricated structural elements, other than walls, with force
applied at center of gravity of assembly.
|
Any Horizontal Direction
|
0.30
|
|
Connections for exterior panels or elements.
|
Any Direction
|
2.00
|
|
1
|
See Section 11-136(b) for use of Cp.
|
|
2
|
When located in the upper portion of any building with a hn/D
ratio of 5 to 1 or greater the value shall be increased by 50%.
|
|
3
|
For flexible and flexibly mounted equipment and machinery, the
appropriate values for Cp shall be determined with consideration given
to both the dynamic properties of the equipment and machinery and
to the building or structure in which it is placed.
|
|
4
|
The Wp for storage racks shall be the weight of the racks plus
contents. The value of Cp for racks over two storage support levels
in height shall be 0.15 for the levels below the top two levels.
|
|
5
|
The design of the equipment and machinery and their anchorage
is an integral part of the design and specification of such equipment
and machinery. The structure to which the equipment or machinery is
mounted shall be capable of resisting the anchorage forces (see also
Section 2312(k)).
|
|
6
|
Floor and roofs acting as diaphragms shall be designed for a
minimum force resulting from a Cp of .12 applied to Wp unless a greater
force results from the distribution of lateral forces in accordance
with Section 2312(e).
|
|
TABLE NO. 13-F
ALLOWABLE VALUE OF HEIGHT-THICKNESS
| ||
|---|---|---|
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RATIO OF UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR.1,2
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BUILDING WITH CROSSWALLS AS DEFINED BY SECTION 11-132
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ALL OTHER BUILDINGS
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Walls of One Story Buildings
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16
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13
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First Story Wall of Multistory Buildings
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16
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15
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Walls in Top Story of Multistory Buildings
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14
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9
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All Other Walls
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16
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13
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1
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Minimum quality mortar shall be determined by laboratory testing
in accordance with Section 11-138(2)e.
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2
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Table 13-F is not applicable to buildings of rating classification I. Walls of buildings within rating classification I shall be analyzed in accordance with Section 11-136(6).
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TABLE NO. 13-G
VALUES FOR EXISTING MATERIALS
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|---|---|
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EXISTING MATERIALS OR CONFIGURATION OF MATERIALS1
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ALLOWABLE VALUES
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1. HORIZONTAL DIAPHRAGMS
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|
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a. Roofs with straight sheathing and roofing applied directly
to the sheathing.
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100 lbs. per foot for seismic shear.
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b. Roofs with diagonal sheathing and roofing applied directly
to the sheathing.
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400 lbs. per foot for seismic shear.
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c. Floors with straight tongue and groove sheathing.
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150 lbs. per foot for seismic shear.
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d. Floors with straight sheathing and finished wood flooring.
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300 lbs. per foot for seismic shear.
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e. Floors with diagonal sheathing and finished wood flooring.
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450 lbs. per foot for seismic shear.
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f. Floors or roofs with straight sheathing and
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Add 50 lbs. per foot to the allowable values for plaster applied
to the joist or rafters.2
Items 1a and 1c.
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2. SHEAR WALLS
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Wood stud walls with lath and plaster.
100 lbs. per foot each side for seismic shear.
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3. PLAIN CONCRETE FOOTINGS
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fc = 1500 psi unless otherwise shown
by tests.
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4. DOUGLAS FIR WOOD
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Allowable stress same as No. 1 D.F.3
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5. REINFORCING STEEL
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ft = 18,000 lbs. per square inch maximum.3
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6. STRUCTURAL STEEL
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ft = 20,000 lbs. per square inch maximum.3
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1
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Material must be sound and in good condition.
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2
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The wood lath and plaster must be reattached to existing joists
or rafters in a manner approved by the Department.
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3
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Stresses given may be increased for combinations of loads as
specified in Section 11-136(7)b.
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TABLE NO. 13-H
ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH EXISTING
CONSTRUCTION1
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|---|---|
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NEW MATERIALS OR CONFIGURATION OF MATERIALS
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ALLOWABLE VALUES
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1. HORIZONTAL DIAPHRAGMS
Plywood sheathing applied directly over existing straight sheathing
with ends of plywood sheets bearing on joists or rafters and edges
of plywood for blocked diaphragms.*
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Same as specified in Table No. 25-J of this Code located on
center of individual sheathing boards.
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2. SHEAR WALLS
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|
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a. Plywood sheathing applied directly over existing wood
studs. No value shall be given to plywood for shear walls.
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Same as values specified in Table No. 25-K applied over existing
plaster or wood sheathing.
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b. Drywall or plaster applied directly over existing wood
studs.
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75 percent of the values specified in Table No. 47-I.
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c. Dry wall or plaster applied directly over existing wood
studs.
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331/3 percent of the values specified in Table No. 47-I.
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3. SHEAR BOLTS
Shear bolts and shear dowels embedded a minimum of 8 inches
into unreinforced masonry walls.
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100 percent of the values for solid masonry centered in a 2½
inch diameter hole with dry-pack specified in Table No. 24E. No values
larger than those given for 3/4 inch bolts shall be used for nonshrink
grout around circumstance of bolt or dowel.1
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4. TENSION BOLTS
Tension bolts and tension dowels extending entirely through
unreinforced masonry walls secured with bearing plates on far side
of wall with at least 30 sq. inches of area.3
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1200 lbs. per bolt or dowel
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5. WALL ANCHORS (11-138(2)a.)
Bolts extending to the exterior face of the wall with a 2½
inch round plate under the head. Installed as specified for shear
bolts. Spaced not closer than 12 inches on centers.1,2
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600 lbs. per bolt.
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6. Bolts or dowels extending to the exterior face of the
wall with a 2½ inch round plate under the head and drill at
an angle of 22½ degrees to the horizontal. Installed as specified
for shear bolts.1,2
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1200 lbs. per bolt or dowel.
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7. INFILLED WALLS
|
|
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Reinforced masonry infilled openings in existing unreinforced
masonry walls with keys or dowels to match walls.
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Same as values specified for unreinforced masonry reinforcing.
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8. REINFORCED MASONRY
Masonry piers and walls reinforced per Section 2407.
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Same values as specified in Division 26, UBC.
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9. REINFORCED CONCRETE
Concrete footings, walls and piers reinforced as specified in
Division 26 and designed for tributary loads.
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Same values as specified in Division 26, UBC.
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10. EXISTING FOUNDATION LOADS
Foundation loads for structures exhibiting no evidence of Calculated
existing foundation loads due to settlement.
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Maximum dead load plus live load may be increased 25% for dead
load, and may be increased 50% for dead load plus seismic load required
by this Division.
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NOTES:
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|---|---|
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*
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All tables that do not carry a 13 number are found in the Uniform
Building Code, 1985 Edition.
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1
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Bolts and dowels to be tested as specified in Section 11-137(6).
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2
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Bolts and dowels to be 1/2 inch minimum in diameter.
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TABLE NO. 13-I
ALLOWABLE SHEAR STRESS FOR TESTED UNREINFORCED MASONRY WALLS
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|---|---|---|
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Eighty percent of test
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Average test
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Seismic in-plane results in psi not less results of shear based
on than cores in psi gross area1
|
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30 plus axial stress
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20
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3 psi
|
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40 plus axial stress
|
27
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4 psi
|
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50 plus axial stress
|
23
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5 psi
|
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100 plus axial stress or more
|
67 or more
|
10 psi max
|
|
1
|
Allowable shear stress may be increased by addition of 10% of
the axial stress due to the weight of the wall directly above.
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GLOSSARY OF SYMBOLS AND NOTATIONS
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|---|---|---|
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C
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=
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Numerical coefficient as specified in Section 2312(d)
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Cp
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=
|
Numerical coefficient as specified in Section 2312(g) and as
set forth in Table No. 23-J
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D
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=
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The dimension of the structure, in feet, in a direction parallel
to the applied forces
|
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fc
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=
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Specified compressive strength of concrete, psi
|
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Fp
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=
|
Lateral forces on a part of the structure and in the direction
under consideration
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ft
|
=
|
Allowable tensile stress, psi
|
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hn
|
=
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Height in feet above the base to level n
|
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I
|
=
|
Occupancy Importance Factor as set forth in Table No. 23-K
|
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S
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=
|
Numerical coefficient for site-structure resonance
|
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V
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=
|
The total lateral force or shear at the base
|
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W
|
=
|
The total dead load as defined in Section 2302 including the
partition loading specified in section 2304(d) where applicable
|
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Wp
|
=
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The weight of a portion of a structure or nonstructural component
|
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Z
|
=
|
Numerical coefficient dependent upon the zone as determined by Figure No. 1, of Chapter 23. All areas in California are classified in Zones 3 or 4. For locations in Zone No. 3, Z = 3/4. For locations in Zone No. 4, Z = 1
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(Ord. 87-33 1-5-88)
