Ordinance 1989-20ORDINANCE NO. 89 - 20
ORDINANCE OF THE COUNCIL OF THE CITY OF GILROY SETTING FORTH A SEISMIC HAZARD
IDENTIFICATION PROGRAM FOR UNP~INFORCED MASONRY BUILDINGS.
WHEREAS, the State of California has enacted Senate Bill 547, requiring
seismic hazard identification of unreinforced masonry buildings; and
WHEREAS, the City Council desires to lessen the risks to life and property
of the citizens of the City of Gilroy as posed by earthquakes; and
WHEREAS, the City Council has concluded that it wishes to implement a
seismic hazard identification program to require owners of unreinforced masonry
buildings to investigate the potential hazards of their buildings;
NOW, THEREFORE, the City Council of the City of Gilroy does adopt this
ordinance as follows:
SEISMIC HAZARD IDENTIFICATION PROGRAM
FOR UNREINFORCEDNASONR¥ BUILDINGS
Sections:
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Purpose
Definitions
Scope of program
Building owner notification
Recording
Engineering reports
Letters of intent
Mitigation options
Historic properties
City review of engineering reports and letters of intent
Building tenant notification
Progress reports to City Council
Interpretations
Penalties
Effective date.
Section 1: Purpose. It is generally acknowledged that the City of
Gilroy is located in a geographic area of high seismic risk, due to its proximity
to both the San Andreas and Calaveras faults, and may reasonably be expected to
experience moderate to severe ground shaking in the event of a significant local
earthquake. Such ground shaking could result in serious injury or loss of life
due to damage or collapse of buildings. Historically, unreinforced masonry
buildings have been shown to be especially vulnerable. The purpose of this
ordinance is to promote public safety by identifying those buildings in the City of
Gilroy which exhibit structural deficiencies in their capacities for earthquake
resistance, and by determining the severity and extent of those deficiencies in
relation to their potential for causing injury or loss of life.
Section 2:
definitions apply:
Definition. For purposes of this ordinance the following
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ORDINANCE NO. 89 - 20
(a) "Civil engineer or structural engineer" means a licensed civil or
structural engineer registered by the State of California pursuant to the rules and
regulations of Title 16, Chapter 5 of the California Administrative Code.
(b) "Uniform Building Code (UBC)" is as published by the International
Conference of Building Officials, Whittier, California, as adopted by the City of
Gilroy.
(c) "Unreinforced masonry (URM) building" means any building containing
walls and/or columns constructed wholly or partially of masonry without at least
fifty percent (50%) of the reinforcement required by the 1985 edition of the UBC,
and includes:
2.
3.
4.
5.
Unreinforced brick masonry
Unreinforced concrete masonry
Hollow clay tile
Adobe or unburned clay masonry
Stone masonry.
(d) Other terms are as defined in the 1985 edition of the UBC.
Section 3: Scope of Program. Owners of all URM buildings in the City
of Gilroy, except as exempted below, shall be required to have an engineering
report submitted to the City's Building Division, to determine the existence,
nature, extent and severity of structural deficiencies in their buildings'
capacities for earthquake resistance which could result in damage or collapse with
possible Injury or loss of life.
(a) Exempted Buildings. The following buildings are exempted from
complying with this ordinance:
Be
Residential buildins with five (5) or fewer dwelling units.
Warehouses or similar structures not used for human habitation,
except for warehouses or structures housing emergency services
equipment or supplies.
Buildings which have already been structurally upgraded in
substantial accordance with either the 1973, or later, edition of
the UBC or the City of Los Angeles Division 88 Standard for URM
Buildings.
Section 4: Building Owner Notification. Owners of buildings included
in the scoppe of this program shall be notified within six (6) months of the
enactment of this ordinance by the Building Division of the City of Gilroy that
each such building has been included in the City's list of potentially hazardous
URM buildings, and is required to have an engineering report submitted to the City.
Section 5: Recording. At the time of building owner notification,
the Chief Building Official shall file with Office of the County Recorder a
certificate stating that the subject building falls within the scope of this
ordinance, has been included in the City's list of potentially hazardous URM
buildings, and is required to comply with the provisions contained herein. At such
later time as each such identified building has either been determined as
excludable from the City's list by further investigation, or has undergone
mitigation of Its hazards to the satisfaction of the Chief Building Official, the
Chief Building Official shall then file with the Office of the County Recorder a
certificate stating that the building has been removed from the potentially
hazardous classification.
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ORDINANCE NO. 89 - 20
Section 6: Engineering Reports. Owners of identified buildings shall
submit engineering reports to the Building Division of the City of Gilroy as
follows:
(a) Timeframe. Engineering reports shall be submitted within two (2) years
of building owner notification.
(b) Authorized Preparers. Engineering reports shall be prepared by civil
or structural engineers, as previously defined herein, who are familiar with
seismic analysis and design.
(c) Purpose. The purpose of each such engineering report shall be to
investigate, in a thorough and unambiguous fashion, a building's structural systems
that resist earthquake forces, and to evaluate their adequacy to resist the seismic
design forces as specified herein.
(d) Engineering Standards. The engineering standards to be used in
preparation of engineering reports shall be the 1985 edition of the UBC as modified
by Appendices A and B of this ordinance.
(e) Format. The format for engineering reports shall be as outlined in
Appendix B of this ordinance, or other equivalent format approved in writing by the
Chief Building Official.
(f) Availability. Copies of engineering reports submitted shall be
available to the public for review at the Building Division upon request.
Section 7: Letters of Intent. A letter of intent shall be submitted
within ninety (90) days of submittal of each engineering report, and shall
describe in general fashion how the building owner intends to approach hazard
reduction of his or her building.
Section 8: Mitigation Options. Options available to the building
owner for approaching hazard reduction include, but are not limited to, the
following:
(a) Structural rehabilitation of the building to meet or exceed the seismic
provisions of the engineering standards referenced herein.
(b) Change in use of the building to a residential or warehouse occupancy
exempted from compliance with this ordinance, as previously described herein, as
may be allowed by other City ordinances.
(c) Sale of the building to a new owner, who shall then bear the
responsibility of hazard reduction.
(d) Vacating the building pending further investigation of possible
alternatives.
(e) Demolition of the building, or portions thereof, to eliminate the
potentially hazardous conditions.
Section 9: Historic Properties. Any building which qualifies as
"historical property" as determined by an appropriate governmental agency under
Section 37602 of the Health and Safety Code shall be retrofitted in accordance with
the State Historical Building Code.
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ORDINANCE NO. 89 - 20
Section 10: City's Review of Engineering Reports and Letters of
Intent. The Building Division shall review the documents submitted for each
identified building for conformance to this ordinance. The Building Division may,
at its option, engage the services of consulting civil or structural engineers to
assist in evaluation of documents submitted. Costs of each such review shall be
recovered by fees assessed upon the building owner at the time of submittal of
documents, based upon the time required for review of any structural rehabilitation
plans subsequently submitted for building permit purposes for work directly related
to compliance with this Ordinance.
Section 11: Building Tenant Notification. Owners of each identified
building shall provide each of their tenants with written notification that a
seismic investigation of their building has taken place, and that the engineering
report documenting the investigation is available for review at the Building
Division. Such notification shall occur within ninety (90) days of submittal of
each engineering report. Each building owner shall also submit to the Building
Division written confirmation of tenant notification, in the form of a signed
affidavit or other equivalent means as approved by the Chief Building Official.
Section 12: Progress Reports to City Council. The Building Division
shall prepare annual progress reports to the City Council on the implementation of
this ordinance and its effects on voluntary hazard reduction by building owners.
Section 13: Interpretations. The interpretation of the Chief Building
Official shall prevail on matters relating to the implementation of this ordinance.
Section 14: Penalties. Nonconformance with this ordinance is
unlawful. Violation constitutes an infraction and is subject to civil prosecution
under the laws and ordinances of the City of Gilroy.
Section 15: Effective Date. This ordinance shall become effective on
the thirty-first day after the day of its passage.
PASSED AND ADOPTED this 4th day of December, 1989, by the following vote:
AYES:
NOES:
COUNCILMEMBERS: GAGE, HALE, KLOECKER, MUSSALLEM, NELSON, VALDEZ
and HUGHAN.
COUNCILMEMBERS: None
ABSENT: COUNCILMEMBERS: None
ATTEST:
APPROVED:
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ORDINANCE NO. 89 - 20
APPENDIX A
PROCEDURES FOR INVESTIGATION OF URM BEARING WALL BUILDINGS
(a) Preliminary Field Survey. From existing plans or from
field investigation prepare framing plans for roof and upper floors
noting all beams, trusses, and major lintels at bearing walls.
Prepare elevations of all URM walls noting the location and size of
all openings in the walls.
(b) Items for Special Investigation.
(1) Identify and include on the plans all parts of the
vertical load carrying system that may act as ties to lateral load
resisting elements, to determine the elements that may control the
relative displacement between the building's base and roof.
(2) Identify and include on the plans all undamaged
interior crosswalls that are continuous between the ground floor and
roof noting if these are connected to the upper floor or roof by
methods other than attachment of wall and ceiling finishes.
(3) Examine and draw the relationship of the roof or
floor framing to the ceiling framing (if separate) to determine the
method if any of their interconnection.
(4) Identify and include on the plans the support system
for any URM walls that are not continuous to the base of the
building noting the materials used for this support. (e.g. steel
frame).
(5) Identify and include on the plans a description of
the floor and roof sheathing and their attachment. Note any
difference in materials on a given level that could lead to
substantial variations in diaphragm stiffness. Note the sizes and
locations of openings in diaphragms adjacent to URM walls. Identify
the roof covering system used and note if there are locations where
it is on a cricket or other superimposed deck.
A thorough investigation of the roof diaphragm is necessary to
permit the evaluation of the compatibility of its stiffness with the
out-of-plane stability of the URM walls of the story immediately
below the roof as required in section (c) of the analysis procedure
of this appendix.
(c) InvestiGation of Existing Anchorage of URM Walls to UDDer
Floor and Roof. Indicate the locations of ali"existing
wall anchors on the roof/floor framing plans and specify their
spacing, size and method of connection. If existing anchors are to
be utilized as connections for resisting lateral force in the
analysis these will require testing as specified in section (e)l.
(d) InvestiGation of Existina URM Walls. Investigate the
following items if they occur in the building, and determine:
(1) The thickness of URM walls at all levels and locations
of any changes in thickness. Substantial changes in wall thickness
or stiffness shall be considered in the analysis for out-of-plane
and in-plane wall stability. Variations in wall..stiffness caused by
openings such as small windows and doors need not be considered.
(2) materials used for lint~ or arches at openings
~d their bearing areas and connection to supporting columns or
piers. The materials used for columns or piers supporting lintel
beams or arches.
(3) The heights of parapets, cornices and gable ends of
URM walls above the uppermost existing anchorages.
(4) The anchorage or bonding of terra cotta, cast-stone
brick veneer or similar facing materials to the backup wythes of
brickwork at cornices and other architectural appendages.
(5) The coursing of exterior wythes of masonry, the
bonding of wythes of masonry, and the materials used in each wythe.
An examination of the wall joint between wythes (collar joint) must
be made at each in-plane shear test location to estimate the
percentage of wythe to wythe mortar coverage and the estimate shall
be reported with the results of the tests.
Wythes of walls Dot bonded as described below shall be
considered veneer. The veneer wythe shall not be included in the
effective thickness of the wall used to calculate the height-to-
thickness ratio and the shear capacity of the wall, and methods for
its adequate anchorage must be devised.
All units of URM bearing and non-bearing walls shall be laid
with full shoved mortar joints; all head, bed and collar joints
shall be solidly filled with mortar; and the bonding of adjacent
wythes of multi-wythe walls shall be as follows:
The facing and backing shall be bonded so that not less than 4
percent of the wall surface of each face is composed of headers
extending not less than four inches into the backing. The distance
between adjacent full length headers shall not exceed 24 inches
vertically or horizontally. In walls where a single header does not
extend through the wall, headers from the opposite sides shall
overlap at least four inches, or headers from opposite sides shall
be covered with another header course overlapping the header below
at least four inches.
(6) The condition of mortar joints and the locations of
any existing cracks or damaged portions of wall elements.
(e) Testinq. The testing of existing wall anchorage systems
must be made to determine an average capacity when these anchors are
to be used in the analysis of the building's current resistance to
lateral forces. The testing of existing URM walls to determine the
allowable bed-joint shear is required for all buildings. ~
(1) Existing Wall Anchors in URM Walls. Five percent of
the existing rod anchors shall be tested in pullout by an approved
testing laboratory. The minimum tested quantity shall be four per
floor or roof level with two tests where framing is perpendicular to
the wall and two where framing is 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.
Where due to obstructions this is not possible, details of the
condition encountered and the alternate method used must be included
in the test report, with calibration adjustment for conditions where
the reaction of the test apparatus contributes tq the tension value
of the anchor. The rod anchor shall be given a preload of 300
pounds prior to establishing a datum for recording elongation. The
tension load reported shall be recorded at 1/8 inch relative
movement of the anchor to the adjacent masonry wall surface. The
allowable resistance of existing anchors shall be 40 percent of the
average of those tested anchors having the same wall thickness and
joist orientation.
(2) In-Place Shear Test of Brick Masonry. 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. Steel bearing plates
of the full dimension of the brick shall be inserted at each end of
the test jack. The bearing plates shall not contact the mortar
joints. The shear stress shall be based on the gross area of both
bed joints and shall be that at which movement of the adjacent brick
is first observed.
The minimum quality mortar in 80 percent of the shear tests
shall not be less than the total of 30 psi when reduced to an
equivalent zero axial stress. If the larger height-to-thickness
ratios allowed by footnotes %5 and %6 of Table A-2 are to be
utilized in the analysis, all shear tests taken at the top story
must be included in the 80 percent or'the shear tests used to
determine the minimum mortar shear strength.
The minimum quantity of tests shall be as follows: At each
story not less than two per wall line or line of wall elements
providing a common line of resistance to lateral forces, with not
less than one per 1500 square feet of wall surface and not less than
a total of eight per building. In single story buildings the wall
above the lintel beam at an open storefront need not be tested.
The exact test locations shall be determined by the engineer
responsible for the investigation and noted on the documents
submitted to the City. The tests should be conducted at least two
brick courses above or below the bond course and be distributed
vertically to include a variety of dead load surcharge conditions.
Test locations shall be representative of the mortar conditions
throughout the entire building, taking into account variations in
workmanship, variations in weathering of exterior surfaces and
variations of interior surfaces due to deterioration caused by leaks
and condensation of water and/or by other deleterious substances
contained within the building.
(a)
STANDARDS FOR THE ANALYSIS AND EVALUATION OF
UN'REINFORCED MASONRY BEARING WALL BUILDINGS
Structural Analysis Procedures
accordance with the following equation:
(1) The total seismic forces should be computed in
V =ZIKCSW
WHERE:
The value of KCS shall equal .100
The value of Z and I shall equal 1.0.
The value of W shall be as defined in Chapter 23 of the 1985
Uniform Building Code (UBC).
(2) Parts or portions of the building shall be analyzed
for lateral loads in accordance with Chapter 23 of the 1985 UBC but
not less that the value from the following equation: Fp = ICpSWp
WHERE: The product of I__S shall be 0.75
The value of Cp shall be as set forth in Table 23-J of
the 1985 UBC and shall equal 0.16 for diaphragms.
The value of W_~ shall be as defined in the 1985 UBC.
Exception: URM walls may be analyzed as indicated in Section
(b) below.
(3) The structural elements of the building required to
be analyzed shall include the following:
Wall height-to-thickness ratio and in-plane shear forces.
Tension bolts (in bending) if used to resist lateral forces.
Parapets for out-of-plane loading.
Diaphragm stress and diaphragm chords at floors and roof.
(4) Anchorage and interconnection of all parts, portions
and elements of the structure resisting lateral forces shall be
analyzed in accordance with the 1985 UBC and the formula in
Subsection (2) above.
A complete and continuous load path from every part or portion
of the structure to the foundation shall be shown to exist for the
required lateral forces. All parts, portions and elements of the
structural systems shall be shown to be interconnected by an
adequate positive means.
(5) Except as modified herein, the lateral analysis of
the building shall be in accordance with the analysis specified in
the 1985 UBC.
Stresses in existing materials and construction utilized to
transfer seismic forces shall conform to either those permitted by
the 1985 UBC or those permitted for types of materials and
configurations specified in Table A-3 or those described in Section
(b) below. When calculating' shear or diagonal tension stresses due
to seismic forces, existing masonry shear walls may be allowed to
resist 1.0 times the required forces in lieu of the 1.5 factor
required by the 1985 UBC.
(6) Masonry walls not anchored to all floors and roof to
resist a minimum of 200 pounds per linear foot acting normal to the
wall at the level of the floor or roof shall be considered
inadequate. No allowable tension stress will be permitted in URM
walls, except as permitted by section (b)l of this appendix. URM
walls not capable of resisting the required design forces specified
in this section shall be deemed inadequate.
In addition to seismic forces, URM walls shall be analyzed as
specified in Chapter 24 of the 1985 UBC to withstand all vertical
loads.
Exception: URM Walls which carry no design loads other than
their own weight may be considered veneer if they
adequately anchored to elements which are not part
of the existing lateral force resisting system. See
section (d) 5 under Procedures for Investigation to
determine if existing walls mus% be considered as
veneer.
(7) When stresses in existing lateral force resisting
elements are due to a combination of dead and live plus seismic
loads, the allowable working stress specified in the 1985 UBC may
increased by 100 percent. However, no increase will be permitted in
the stresses allowed in Section (b) below and the stresses in
members due to only seismic and dead loads shall not exceed the
values permitted in the 1985 UBC. In addition, the calculated
tensile fiber stress due to seismic forces may be reduced by the
full direct stress due to vertical dead loads.
(b) Materials of Construction Standards
(1) Unreinforced masonry walls analyzed in accordance
with this section may provide support for roof and floor
construction and resistance to lateral loads under the conditions
set forth below.
The bonding of such walls shall conform to those specified in
Section (d) 5 of the Procedures for Investigation.
Tension stresses due to seismic forces acting normal to the
wall may be neglected if the wall does not exceed the height-to
thickness ratio and the allowable in-plane shear stresses due to
seismic loads set forth in Tables A-2 and A-4 respectively.
If the wall height-to-thickness ratio exceeds the specified
limits, the wall will be considered inadequate unless braced by
vertical members designed to satisfy the requirements of the 1985
UBC. The deflection of such bracing members at design loads shall
not exceed one-tenth of the wall thickness.
Exception: The wall may be supported by flexible vertical
bracing members that comply with the requirements of Section (a) 2
of the analysis procedure if the deflection at design loads is not
less than one-quarter nor more than one-third of the wall thickness
in the story under consideration.
Any existing or new vertical bracing used for this purpose
shall be attached to floor and roof construction independently of
existing wall anchors and the horizontal spacing of the members
shall not exceed one-half the unsupported height of the wall or ten
feet, whichever is greater.
(2) Minimum Acceptable Quality of Existing URM Walls. 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 Section (e) 2 of the Procedures for
Investigation. All masonry used to resist seismic forces shall be
undamaged by shear failure cracking and be of a quality not less
than the minimum standards established or shall be considered
inadequate.
Pointing of all masonry wall joints may be performed prior to
the testing if joints are raked and cleaned to remove loose and
deteriorated mortar. Mortar pointing shall be Type S or N, except
masonry cements shall not be used. All preparation and pointing
shall be done under the continuous inspection of a special inspector
whose reports shall be included in the testing report.
The design seismic in-plane shear stresses shall be related to
test results in accordance with Table A-4. Intermediate. values
between 5 and 10 psi may be interpolated.
Compression stresses for unreinforced masonry having a minimum
design shear value of 3 psi shall not exceed 100 psi and design
tension values shall not be permitted.
(3) Existing Roof, Floors, and Walls. Existing undamaged
materials, including wood shear walls may be analyzed as part of the
lateral load resisting system, provided that the stresses in these
materials do not exceed the values shown in Table A-3. New plywood
shear walls designed in accordance with the 1985 UBC may be
recommended to strengthen portions of the existing seismic resisting
system.
Diaphragm chord stresses of horizontal diaphragms ~shall be
developed in existing materials or be considered inadequate.
(4) Minimum URM Wall Anchorage. Ail URM walls shall be
anchored at both floors and roof by existing rod anchors at a
maximum spacing of six feet and be secured to the joists or rafters
to develop the required forces. At the building corners at roof and
floor levels combination shear and tension anchors shall be located
not more than two feet horizontally from the inside corners of the
wall. Testing of existing rod anchors shall be conducted according
to Section (e) 1 of the Procedures for Investigation. Walls without
anchors having the necessary locations, spacing or capacity will be
considered inadequate.
(5) Minimum Vertical Support. Where trusses or beams
other than rafters or joists and beams supporting walls above open
storefronts are supported on URM piers, these piers must be
evaluated and shown to provide adequate vertical support during
seismic loading or shall be independently supported by a vertical
element other than the URM wall pier.
(6) Minimum Parapet Bracing. Parapets and exterior wall
appendages not capable of resisting the forces specified in Section
(a) shall be considered hazardous. The maximum height of an
unbraced UKM wall parapet above the roof sheathing, shall not exceed
one and one-half times the thickness of the parapet wall.
(c) Design Check for Compatibility of Roof Diaphragm Stiffness
~o the Out-of-Plane Stability of URM Walls.
(1) General. The requirements of this section are in
addition to the other analysis requirements of Section (a). This
section contains a procedure for the evaluation of the out-of-plane
stability of unreinforced masonry walls anchored to wood diaphragms.
The relative stiffness and strength of a diaphragm Governs the
amount of amplification of seismic Ground motion by the diaphragm,
and therefore, a diaphragm stiffness and strength related check of
the out-of-plane stability of URM walls must be performed.
(2) Definitions. The following definitions are
applicable to this section:
CROSS WALL is a wood framed wall having a height-to-length
ratio complying with 1985 UBC Section 4713(d) or Table 25-I and is
sheathed with any of the materials described in Table A-1. The
total strength of all cross walls located within any 40 feet length
of diaphragm measured in the direction of the diaphragm span shall
not be less than 30 percent of the strength of the diaphragm in the
direction under consideration
DEMAND CAPACITY RATIO (DCK) is a ratio where:
DEMAND equals lateral forces due to 33 percent of the combined
weight of the diaphragm and the tributary weight of walls and other
elements anchored to t.he diaphragm.
CAPACITY equals the diaphragm's total shear strength in the
direction under consideration as determined using the values in
Table A-1.
D = the depth of the diaphragm, in feet, measured perpendicular
to the diaphragm span.
h/t = the height-to-thickness ratio of an unreinforced masonry
wall. The height shall be measured between wall
anchorage levels and the thickness shall be measured
through the wall cross section at the level under
consideration.
L = span of diaphragm between masonry shear walls or steel
Vc = the total shear capacity of cross walls in the direction
of analysis immediately below the diaphragm level being
investigated as determined by using Table A-1.
vu = Maximum shear strength in pound per foot for a diaphragm
sheathed with any of the materials Given in Table A-1.
Wd = total dead load of the diaphragm plus the tributary weight
of the walls anchored to the diaphragm, the tributary
ceiling and partitions, and the weight of any other
permanent building elements at the diaphragm level under
consideration.
(3) Design Check Procedure. The demand-capacity ratio
(DCR) shall be calculated by the following equations:
Buildings without crosswalls
0.33 Wd
DCR =
2 vu D
Buildings with crosswalls
0.33 Wd
DCR =
.2 vu D + Vc ~.
DiaPhragm Deflection. The calculated DCR shall be the left of
the curve in Figure A-5. Where the calculated DCR is outside (to
the right) of the curve, the diaphragm's deflection limits are
exceeded and cross walls are needed to reduce the deflection.
URM Wall Out-of-Plane Stability. The DCR shall be calculated
discounting any existing cross walls. If this DC~ value
corresponding to the diaphragm span is to the right of the curve in
Figure A-5, the region within the curve at and below the
intersection of the diaphragm span with the curve may be used to
determine the allowable h/t values per Table A-2.
7
TABLE A-1
ALLOWABLE VALUES FOR EXISTING WALLS AND DIAPHRAGMS
ONLY FOR DETERMINATION OF THE DIAPHRAGM DEMAND / CAPACITY RATIO
1. Horizontal Diaphragms
a. Roofs with straight sheathing
and roofing applied directly
to the sheathing.
100 PLF for seismic shear
b. Roofs with diagonal sheathing
and roofing applied directly
to the sheathing.
250 PLF for seismic shear
2. Crosswalls I
a. Plaster on wood or metal
lath
200 PLF per side for
seismic shear
b. Plaster on gypsum lath
175 PLF per side for
seismic shear
c. Gypsum wallboard unblocked
75 PLF per side for
seismic shear
d. Gypsum wallboard edges blOcked
125 PLF per side for
seismic shear
Footnotes:
1. Materials must be undamaged and in good condition.
TABLE A-2
ALLOWABLE VALUE OF HEIGHT-TO-THICKNESS (H/T) RATIO
OF URM WALLS WITH MINIMUM QUALITY MORTAR ~' = '
Buildings with All Other
Complying Crosswalls 3 Buildings
One Story Building Walls
First Story Walls of
-Multi-Story Buildings
Walls in Top Story of
Multi-Story Buildings
All Other Walls
13 - 16 4. ., 6 ~ 13
!
16 I 15
9-144, ~, ~ ~ 9
16 ' 13
Footnotes:
Minimum quality mortar shall be determined by testing described
in Section (e) 2 of the Procedures for Investigation and shall
include all top story tests in the 80 percent of tests used if
the higher ratio values permitted in footnotes 5 and 6 are used.
See section (c) for determination of the demand capacity ratio
values to be used in conjunction with Figure A-5 to determine if
the building can qualify as a building containing crosswalls.
e
Qualifying crosswalls are defined as interior walls of masonry
or wood frame construction with surface finish of wood lath and
plaster, 1/2 inch thick gypsum board, or solid horizontal wood
sheathing. They may not exceed 40 feet horizontal separation,
must be continuous through all stories and have a minimum length
of 1-1/2 times the story height.
The minimum mortar strengths required in footnotes # 5 and 6
shall be the test shear strength reduced by the effect of axial
stress in the wall at the point of the test.
5. The larger height-to-thickness ratio may be used where mortar
shear tests establish a minimum mortar shear strength of not
less than 100 psi or where the tested mortar shear strength is
not less than 60 psi and a visual examination of the vertical
wythe-to-wythe (collar) joint indicates not less th~ 50 percent
mortar coverage.
6. Where a visual examination of the collar joint indicates not
less than 50 percent mortar coverage and the minimum mortar
shear strength is greater than 30 psi but not less than 60 psi,
the allowable h/t ratio may be determined by linear
interpolation between the larger and smaller values given in
direct proportion to the mortar shear strength.
TABLE A-3
ALLOWABLE STRESS VALUES FOR EXISTING MATERIALS
FOUND TO BE UNDAMAGED AND IN GOOD CONDITION
1. Horizontal Diaphragms
Roofs with straight sheathing
with the roof covering applied
directly to the sheathing.
Roofs with diagonal sheathing
with the roof covering applied
directly to the sheathing
Floors with straight tongue
and groove sheathing
Floors with straight sheathing
and finished wood flooring
ee
Floors with diagonal sheathing
and finished wood flooring
Floors or roofs with straight
sheathing and plaster applied
to the joists or rafters below
2'. Shear Walls
Wood stud walls with lath and
plaster in undamaged condition
3. Plain Concrete Footings
4. Douglas Fir Wood
100 PLF for seismic shear
400 PLF for seismic shear
150 PLF for seismic shear
300 PLF for seismic shear
450 PLF for seismic shear
Add 50 PLF to the allowable
values for items la and lc.
5. Reinforcing Steel ~
6. Structural Steel ~
Footnotes:
1. Stresses may be increased for combination of loads as specified
in Section (a) 7 of the Standards for Analysis and Evaluation.
100 PLF each side for
seismic shear
f'c = 1500 PSI unless
otherwise shown by tests
Same as 1985 UBC values for
No. 1 Douglas Fir ~
f't = 18,000 PSI maximum
f't = 20,000 PSI maximum
10
TABLE A-4
ALLOWABLE SHEAR STRESS FOR TESTED URM WALLS
80 Percent of Test Results
in PSI Not Less Than:
Allowable In-Plane Shear
in PSI Based on Gross Area
30 + Axial Stress
40 + Axial Stress
50 + Axial Stress
100 + Axial Stress or more
3.0
4.0
5.0
10.0 (maximum)
Footnotes:
1. The allowable shear stress may be increased by addition of 10
percent of the axial stress due to the weight of the wall
directly above.
11
540
480
42(
36(
300--
240-
180-
120 -
60--
REGION OF DEMAND/CAPACITY
RATIOS WHERE CROSSWALLS
MAY BE USED TO INCREASE
H/T RATIOS
REGION OF DEMAND/CAPACITY
RATIOS WHERE H/T RATIOS OF
"WITH CROSSWALLS" MAY BE
USED
REGION OF DEMAND/CAPACITY
RATIOS WHERE H/T RATIOS OF
"ALL OTHER BUILDINGS"SHALL
BE USED
O0 ! I ~ 't -~
- 1 2 3 4 5 6
DEMAND/CAPACITY RATIO = 0.33Wd / 2vuD OR 0.33Wd / (2vuD + Vc)
FIGURE A-5
12
APPENDIX B: FORMAT FOR ENGINEERING REPORTS
Engineering reports on URM buildings in the City of Gilroy
shall incorporate the following format.
I. DATA SHEET
This sheet contains general information about the building,
including its address, use/occupancy, .~ate of original
construction, dates of any ~ubsequent structural alterations, names
and addresses of the building's designers, if known, building area,
number of stories, and occupant load calculations.
II. BUILDING DESCRIPTION
A. Configuration. Include descriptions of the building's
size, shape, arrangements of structural elements, sizes and
locations of openings in walls, roof and floors, any irregularities
or discontinuities, non-structural elements (appendages, parapets,
facades), and adjacent buildings if relevant.
B. Construction Materials.
observed conditions.
Indicate types and present-day
C. Site Geology. Provide information as required by the
Chief Building Official for any special site or soil conditions.
III. PLANS OF EXISTING CONSTRUCTION
The following plans shall be included, to the degree of detail
required to adequately show the seismic integrity of existing
conditions.
ae
B.
C.
D.
Ee
F.
G.
H.
Site Plan
Roof Plan
Floor Plans (showing any interior crosswalls)
Roof Framing Plan (and ceiling framing if a separate
system)
Floor Framing Plans
Foundation Plan
Exterior Elevations
Interior Wall Elevations (of any-interior URM partition
walls and other crosswalls)
Structural Building Section(s)
Structural Details (for all lateral load connections)
Appendix B, Page 1
IV. CALCULATIONS TO CHECK EXISTING CONSTRUCTION
Structural calculations shall include the following:
A. Derivation of earthquake demand (seismic design) forces
and their distribution to resisting elements and connections.
Bf Capacities of existing resisting
connections. Include materials testing results.
elements and
C. Capacity/demand ratios (factors of safety) for existing
elements and connections.
V. CONCLUSIONS AND RECOMMENDATIONS
Describe areas found by analysis to be deficient in their
ability to withstand prescribed seismic forces, and their
significance regarding potential collapse or partial collapse.
Discuss in general terms the alternatives available for mitigation
of these inadequacies, and the engineer's recommendations for most
suitable solutions, in sufficient detail to permit the building
owner to obtain cost estimates for repairs.
NOTE: Each engineering report shall bear the signature and
professional registration number, including its expiration date,
of the responsible civil or structural engineer.
Appendix B, Page 2
GILROY TENTATIVE URM LIST
As of October 26, 1989
On North Monterey Street:
1. 7320 841-08-004
2. 7353 799-08-040
3. 7357 799-08-038
4. 7380 841-08-006
5. 7383/87 799-08-035
6. 7400 841-06-061
7. 7401 799-07-067
8. 7445/47 799-07-056
9. 7450/52 841-06-010
10. 7451 799-07~055
11. 7453 799-07-054
12. 7454/60 841-06-011
13. 7459/61 799-07-052
14. 7463 799-07-052
15. 7477 799-07-050
16. 7511 799-06-054
17. 7515 799-06-053
18. 7517 799-06-052
19. 7525 799-06-051
20. 7529/31 799-06-050
21. 7539/41 799-06-048
22. 7543/47 799-06-047
23. 7557 799-06-045/46
24. 7561/65 799-06-044
25. 7562 841-05-060
26. 7568 841-05-061
27. 7573 799-06-043
28. 7574 841-05-064
29. 3579 799-06-042
30. 7598 841-05-065
31. 7680/B 841-04-018
32 . 7760 841-04-0t9
33. 7888 841-02-009
Banning Upholstery (Milias, R)
Vacant (former bar?) (Garcia, Felix)
Porcella'.s Music Store (Porcella)
Pitzer Automotive (Kishimura*)
Augie's Restaurant/Bar (Falk)
Old City Hall Restaurant (City)
Hall's Western Wear (Hall*)
Gilroy Antiques (Garcia, Jesus*)
Hair Etc./Downtown Barber (Villa-
franca, FY)
Nimble Thimble (Gaeta)
Zapateria 6 Hermanos (Topland)
Boot & Shoe Repair/Cielito Lindo
Restaurant (A & W Properties, R, FV)
South County Housing/Rainbow Stained
Glass (Brown, FV)
Kirby's Vaccuum Center (Brownfield*,
R, FV)
USA Beauty Supply (Ginelli*, R)
Monterey Street Antiques (Rizzuto*)
California Music Video (Milias, R)
Rendi's Boutique (Nicholson)
Mr. Art's Shoes (Lang, R, FV)
Leedo Gallery (Pratt, FY)
Baskets D'Royale/Bruhn Clothiers
(Gilroy Improvement Co.*)
Western Auto (Ashford*, R)
Vacant (former Classique Fashions)
(Trinchero*, Buchanan*, R, FY)
Bachelors Club/Gilroy Appliance
Center (Byers*, FV)
Fords Department Store (Ford)
Offices (Buena Vista et. al.)
(Hagins)
Esmeralda's Jewelers (Ferrarini, R)
Crumbles Restaurant (Fo~d)
Beverly Fabrics (Weaver, R)
Rede's Flowers (Machine Shop behind)
(Hagins)
Gilroy Lock 'n Safe/Kelley's Auto
Supply (Sou~h County Alternatives)
Monterey Square (Manzo*, R)
Antique Mall (Kowk)
Elsewhere:
34.
7526/30 Gourmet Alley
799-06-0~.9
35. 55 W. 5th St. 799-06-057
36. 64 W. 5th St. 799-07-044
37. 195 5th St. 799-06-031
38. 60 W. 6th St. 799-08-059
39. 7491 Railroad Ave./
88 Martin 841-06-00i
Lords & Ladys Nail Salon/
Williams Kenpo Karate (Gi!roy
improvement Co.)
Vacant (Station 55) (Anslinger~)
Medical Office (Perry, R, FV)
G~roy Museum (City)
Diamond Signs (Diamond, R)
Storage (Sachara, K)
Need to Add:
40. Chen's ResSauran%
41. Vacant (formerly
Bakery)
*indicates owner or rep at~ended !st public meesing.
R = Sent back response form
FY = Field visited w/ owner or red
New
Gl!roy
I, SUSANNE E. STEINMETZ, City Clerk of the City of Gilroy, do
hereby certify that the attached Ordinance No. 89-20 is an original
ordinance, duly adopted by the Council of the City of Gilroy at a regular
meeting of said Council held on the 4th day of December , 19 89 ,
at which meeting a quorum was present.
IN WITNESS WHEREOF, I have hereunto set my hand and affixed the
Official Seal of the City of Gilroy this 5th day of December
19 89.
(Seal)