Ordinance 1531Cff2DINANCE NO. 1531
Q~F~I~32 16.60 - ~ MASONRY BUILDINGS
AN OF TIC QTY OOUNCII,
OF THE QTY OF CVF~FIZTZTIO
ADDT~ CI~,FI~t 16.60, tlt~fftEII 29~SOPII2Y HUIIDI2JG8
TU ~ CiJPERTII40 MUNICIPAL OOL~.
ZKE QTY OOCIIdCZI, OF ~ C,PiY OF C[JPERl'IIAO HII2EBY ORDAINS AS FOIi0W5;
The... purpose of this Oztiinance is to prcmate public safety aM welfare by
reducing the risk of death ar injury that may result from the effects oP
~. Stx3i builditx~a have been widely rieoognized~far t~
sustaining of life hazaltlous damage as a result of partial ar complete
collapse during past moderate to strcag earthqualaes.
The prwisio~ of this Otdina~e are minimtnn standartfs for etruct:ual
seismic resistance established primarily to reduce the risk of life lose
or injury atxi will not neoegsarily prevent loss of life ar injury ar
prBVent eart2ulualce damage to an existing building whirls om~lies with this
Ordinance.
SOOPE
The requirements of this Ordirsame shall apply to all buildings oorstainirg
unreinforoed masonry bearing walls.
Esaception: This Ortiirsausoe shall net apply to a detached GrCxsp R.
Division 3 Ooaspancy nor to a detached Group R. division 1 Oocaspatscy
containing less than .rive dwelling units used solely for residential
Alternate materials, designs and methods of oonstrssctian may be approved
by the Building Official in aooozdatsos with the Building Code.
16.60.010 - pg~g~
For the purpose of this Ordinsansoe, certain terms are defined as follows:
CR06S FAIZS are interior walls of masonry or wood frame o~sstrssction with
surface finish of wood lath and plaster, mirsinnan 1/2-inch-thick gypsum
wallboani ar solid horizontal wood sheathing. In orrlar to be considered as
a cross .wall within the intent of this cisapter, the csaoss walls shall be
spaced at not more than 40 feet apart in each story, arxi shall be full
story height with a minimum length oP one and aa~e-help times the story
height.
U AASONRY BEARING FALLS are masonry walla having all of the
following charactesistica:
1. Provide the vertical support far a floar ar roof.
2. Have a total superimposed load over 100 pourx9s per linear foot.
3. Have an area of reinforcing steel less than 30 per~oent of that
required by the Building ODde.
~DINANCE 1531 • •
Page -2- ~
(a) General. A historic building may oa~ly with the special provisions
set forth in this ortiinanoe and the provisions of the State Historical
Building Coda.
(b) Unburned Clay Masonry ar Adobe. F3cisting ar re-erec,-ted walls of adobe
oonstsvction shall conform to the Pollowirg:
1. Exterior bearing walls of tmreinforoed adobe maeoauy shall not esaoeed
a heigtst-or length~to-thiclmaea ratio of 5 s 1. S~sch walla shall be provided
with a reinforced bond beam at the top whidi interconnects ail walls. Zhe
bond beam shall have a minim~an depth of 6 indies. Zhs bond beam may have a
width is not leas than a inches, provided the resultirxJ width is not less
than 8 itxhes. Minimmt wall thiclcsess shall be 16 inches for exteriar
bearing walls arxi l0 itx3ses for adobe partitions. No adobe structure shall
exceed arse story in height unless the historic evidence satisfactory to
the Building official indicates a two story heic~st. Zn such cases, the
heic,Qzt-Ito-thic~sess ratio shall ba the same as above for the first story
based on the fatal two story wall height, and the second floor wall
thiclmesa shall runt exceed the ratio of 5:1 by more than 20 percent. Hoed
beams shall be provided at the roof and secorfd floor levels.
2. Foundations footings shall be reinforced ocnctBte under newly
r+ec~sstrueted walls and shall be 50 paroent wider that the wall above,
soil ocx'yditions permitting, except that the foundation wall may be 4
irxdses less in width than the wall if rock, burned brick or stabilized
adobe facing is necessary to provide authenticity.
3. New ar e~dstirrg unstabilized brick and adobe bricJcaasaruy shall test
to 75~ percent of the ocag~resaive strength required by the Building Code
for new material. Unsstabilized brick may be used where existing bricks are
unstabilized arri where the building is not susceptible to flooding or
direct exposure to the weather. Adobe may be allowed a maximum value of 3
pounds per squats inc3i far shear with no increase for lateral forces.
4. Mortar may be of the same soil composition and stabilization as the
brick in lieu of cement mortar.
5. Nominal tension stresses due to seismic forvea normal to the wall may
be neglected if the wall meats the thiola>ess requirements and shear. values
allowed by this subsection.
(c) Ardsaic Matsrials~ Allowable stresses !or archaic materials 'not
specified in this code shall be based on substantiatitq reseaz~ch data ar
engineering judgement with the approval of the Building official.
ORDIN3INCE 1531 • •
Page -3-
(a) General. Every stxt~sre within the Scapa of this Ozdinattce shall be
analyzed and aa~stnx;ted to resist miniiman total lateral seisiaic fa~rnea
asstnned to act nonccocurzently in the directico of each of the main awes
of the structzu:~e in aooordance with the following equation:
Ztse value of IBS need not ewoeed but shall not be less than .100 for one
story kuiidiTr~e with less than 300 oa~artts, and need not ewoeed but mist
not be less than .133 for one story taildiix~s oornaining 100 or more
occupants and buildings over one story above grade. Zhe value of Z and I
shall equal 1.0. Zhe value of W shall be as defined in Chapter 23 of the
1985 Uniform Building Code.
b~ildings~shall be analyzed signed f loads aooordarre
with chapter 23 of the 1985 Uniform Building Oode. E}CCEPFION: Unreinforced
masoiu:y walls may be designed in accordance with Sectico 16.60.040.
Fp ~ IC~b'Wp .......................................(A1-2)
For the pravisicc~ oP this section, the product of IS shall equal 1.0. the
value of Cp shall be in aooordanoe with Table 23 J of the 1985 Uniform
Building Oode. Zhe value of Wp shall be as defined in Chapter 23 0! the
1985 Uniform Building code. E}{CEP'1ZCMT: Unreinfoz+oed masonry walls may ba
designed in aoacrdanoe with Section 16.60.040.
to be) analyzede3 by this Ordinance i~rlude~l~Iieic~t~to-thic]ayess ra~tii of
masonry walls: 2) Tensico bolts in bending; 3) In-plane shear stress: 4)
Parapetai 5) Diaphrac~n stresses and diaphragm d~ords in floors and roof.
(d) Anchorage and Ini:eroonnectico. Anchorage and intar~onnectico of all
parts, porticos and elements of the stricture shall be analyzed and
desi,:gned far' lateral farces in aooordanoe with the 1965 Uniform Building
CDds and the Fbrmula (A1-2) oP this Dods. Masonry walls shall be anchored
to all floors and rvof to resist a minimum Ponce of 200 pounds per linear
foot acting normal to the wall at the level of the floor or roof.
(e) Iavel of Required Repair. Alterations arri repairs zequired to meat
the pravisice:s of this chapter shall oasq~ly with all other applicable
recd+~*+~TM+*+tA of the Building Oode unless specifically provided for in this
Ordinance.
(f) Required Analysis. 1. Ge7fer'al. Dooept as modified herein, the
analysis and design relating to the stn:ctural alteration o! existing
buildings within the scope of this chapter shall be in aoaordance with the
analysis specified in the 1985 Uniform Building Code.
ORDII~NC~ 1531 • •
Page -4-
(f) Required Analysis. 1. C,eneLal. (oontirtued) In addition, the
Crnq~atibility oP the roof diaphtacpn stiffl~esa with the out-of-plane
stability oP the unt+einforoed masonry bearing walla oP the atary
~~i~.te~y below the roof shall be verified in acoott9ance with the
provisions oP Section 16.60.060.
~~;, Buildirxgs ~~•+.th rigid oortcrete or steel and concrete roof
diaphtacyos shall use tt,a l;/t values far all other buildings in Teble Al-F.
`' .~"7~~x.~r t+ «n~letBr castinuaia load path PLCn1 every part
requited horizontal forces. ~ the ~~ shall be provided Par the
3. Positive ocnnections. All parts, portions ar elements of the stzuct<rt+a
shall be interconnected by positive means.
Cg) ~1's~ Prooed<rre 1. Gene2al. Stresses in materials and existing
oonstruetion utilized to transfer seismic Pa~roes Prrm the gz+aud to parts
ar portions of the sttuct<rna shall conform to those pe3mitted by the
Building code and those materials and types oP ~ specified in
Section A7.
2. Ooau~ections. Materials and ooru~ectots used Par the internonnection oP
parts and portions oP the structure shall conform to the Building code.
Nails may be used as a part oP an approved oonnect'.ar.
3. thit+einforoed masonuy walls. In addition to the saimmic !Dross required
by this c3~apter, unrainfor+oed masauy walla shall be analyzed as specified
in the 1985 tlniPorm Building Code to withstand all vertical loads as
specified in the Building Dods. Such walls shall meat the minimina
~ set forth in the Building code.
Fdien calculating shear ar diagonal tension stz+esses due to
seismic !Dross, existing masanty shear walls may be designed to resist 1.0
times tha t~vired forces in lieu of the 1.5 factor required by the
Building Code.
No allowable tension stress will be permitted in unreinfaroed masaray
walls. Walls not capable of resisting the r+egtrired design forces specified
in this at+dinance shall be strengthened ar shall ba r+etroved and t~eplaoed.
EXGEPPIONS: (1) UnrainPotced masonry walla may be analyzed in aooordarne
with Section 16.60.040. (2) Lhsreinforced masonry walls which catty no
design loads other than their own weight may be oansiderod veneer if they
are adequately anchoi~,,d to new suppartirg elements.
S1~bstantial in, wall thic~ess ar stiffness shall be oonsidarad in
the analysis far out-of plans and in-plane wall stability, aril the wall
shall be restrained against out-ofplana instabiliti' b'!' androrage and
bracing to the roof ar Ploos diaphracpn in aooozdanoe with Section
16.60.030(d).
ORDINANCE 1531 •
Page -5-
;, Variations in wall stiffness caused by nominal openirt~a such as
windows and doors need trot be oatrsider+ed.
(h) Combination o! Vertical std Seimmie Forces. 1. New Materials. All
new materials introduced into the st'strCtu>:e to meat the r>3quir~errts of
this Ordintu~roe w2rie3r are subject to combined vertical and horizotrtal
forces shall comply with the Building C-x1e.
2. ~cistllxl materials. 4d~en stress in existing lateral forve resisting
elements re due to a combination o! dead loads plus live loads plus
seismic loads, the allowable working stress specified in the Building Code
may be increased by 100 percent. However, rro increase will be permitted in
the stresses allowed in Sectiatr 16.60.040. The stresses in members due to
only seismic aryl dead loads shall not exceed the values permitted by the
Building Coda.
3. Allowable reduction of bendira stress by Vertical load. Calculated
tensile fiber stress may be redtroed by the full direct stress due to
vertical dead loads.
16.60.040 - NQ~TERIAIB OF C.KTTON
_ (a) ,, All materials permitted by this Dods, including their
appropriate allowable stzessses aryl those exiati:g oonfiguratians of
materials specified herein, may be utilized to meet the requir+~razrts of
this chapter.
(b) t]cistina Materials.
1. Unreinforoed masornv walls. Unreinfonoed masonry walls analyzed in
axart9anoe with this Crdinatroa may provide vertical support for roof and
floor Construction aryl resistance to lateral loads.
All units of both bearing and non-bearing walls shall be laid with full
shoved mortar joints; all head, bed acrd wall (wear) joints shall be
solidly filled with mortar; and the boarding of adjacent wyttres of
multi-wythe walls shall be as follows:
The facing and backing shall be bonded so that not less ttran 4 percetrt
of the wall surface of each face is ocs~rosed of headers exterrdirg not
less than four inches into the backing. The distance between adjacent
full-length treaders shall not exceed 24 inc3res eitt~r Vertically or
trorizonrtally. In walls where a single header does trot extend throuc~i
ttre wall, headers from the opposite aides stroll overlap at least four
itrc3res, or treaders from opposite sides shall be wvered with another
treader Cause overlapping the treader below at least four indrps.
Wythes of walls not bottled as described above shall be CDrL9ider'Bd es
veneer. the veneer wythe shall not be irrrluded in the effective
thiclmess used to calculate ttre treic~rt-to-thictaress ratio acrd the
street capacity of the wall.
ORDIHI~NC'E 1531 •
Page -6-
Unreinfotrert ~~'81']' walls (oontirnsei~
Tension stresses due to seismic fames rsarmal to the wall may be neglected
if the wall does not ew>eed the height-to-thic3Q~esa ratio set rozth in
Table Al-F aryl the in-plane shear stresses due to seismic loads set forth
in Table Al-Z. IP the wall height~tA-th.icla~ess ratio exceeds the specified
limit, the wall may be supported by vertical bracing meanbexs designed to
satiety the ~ and the 198g Uniform Building ode. The
deflection of such bracing members at design loads shall not e>~eed
oa~e-t~tth or the wall thicin~ess.
~~ The wall may be supported by flexible bracing members designed
iri axordarsoe with Secticas 16.60.030(b) of this Ordinance if the
deflection at design loads is net less than one-quarter nar more t~
one-thud or the wall thio7asess at the level under consideration.
All vertical bracing members shall be attached to floor and zcof
oar~struction far their design loads independently of required wall
anchors. xorizonstal spacing of vertical bracing members shall not exceed
one-half the unsupported height or the gall nor ten feet, whichever is
less.
The wall height may be measured yertjrallyr ~ ~4 elem~it8 other than
a floor ar root. Spacing oP bracing elements arxi wall arsctyozs shall not
exceed six teat. Braci„g elements shall be detailed to minimize the
horizontal displaoemesst of the wall by a~onersts of vertical
displaoennents of the floor or roof.
2. yam. Veneer shall be arschored with approved anc3sar~ ties, oonformirg
to the required design capacity specified in Sections 3304 (c) of the 1985
Uniform Building Code, and placed at a maximnn spacirsq or 24 irsdsee.
~IOTI: Existirx) veneer anc3nr ties may be acceptable provided the ties
material condition and oontorm to the mirsim~ms size, maximum spacing and
regsitreaiersts as iniicated below. The veneer andsor ties shall be
corrugated galvanized iris strips not less than cne irscts in width, eic~st
inches in length and once-sixteenth oP an inch in thiclaless and shall be
located and laid in every alternate ooslrse in the vertical height of the
wall at a spacing not to exi;eed 17 irrhes on center horizontally. As an
altexrate, the spacing may be every fourth course vertically at a spacing
not to exceed nine inches on cerster horizontally.
Zlne existence and oonditiars of existing veneer anc3nor ties shall be
verified as follows:
1. An approved testing laboratory shall verify- the locations and
of the ties and shall submit a report to the Building
Official far approval as a part of the structural analysis.
2. The Veneer in a selected area shall be z+etsoved to expose a
representative sanq~le of ties (not less than four) Par irsspection
by the Building Official.
ORDINP,NCE 1531 • •
Page -7-
3. Dci~tir~e roof floors walls footings aril wood ~
bcisting materials, including wood shear walls, may be used as a part of
the lateral load resisting system, provided that stresses in these
materials do not exceed the values shown in Table No. Al-G.
(c) Strengthening of Existinw Materials. New materials, including wood
shear walls may be utilized to stiengther~ portions of the existing seismic
resisting system provided that stzesses do mt e:aceed the values shown in
Table No. Al-H.
(dj Mirtim~ le Quality of F3tistira Lhtreinforced Masonry Walls.
1. General rmvvisians: All unreinforced masonry walls utilized to
carry vertical loads and seismic Poroes parallel and parpeniicular to the
wall plane shall be tested as specified in the subsection. All mnsmty
quality shall equal or exceed the minimmm standazds established herein ar
shall be removed ani replaced by new materials. The quality of mortar in
all masonry walls shall be determined by performing in-place shear tests.
Alternate testing methods may be approved by the Building Official upon
submissia~n of adequate eviderioe to indicate its equivalence. The vertical
wall joint between wythes (collar joint) shall be inspected at each test
location after the in~lace shear tests, arrl an estimate of the percentage
of wythe to wytha mortar coverage shall be reported along with the results
of the in-place shear tests. cdiere the extpsior face is veneer, the type
of veneer, its thickness ani its boaYiitx3 and/or ties to the structural
wall masonry shall also be reported. Nothing shall prat the poir:tinq
with mortal 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 masonry cements shall not be used. All preparation and
mortar poinnting shall be done under the oontitnx~us inspection of a special
inspector. At the aonclusioat of the inspection, the inspector shall sutmit
a written reprtt to the person responsible for the sei~nic analysis of the
building setting forth the results 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 perfornied irnl accordance with
the requirenmenta specified in this section by an approved agency. As
accurate record of ail such tests and their location in the buildirr3 shall
be recorded and thes~a results shall be submitted to the Building Official
for approval as part of the structural analysis.
2. Number and location of tests. The minimms numibar of tests shall
be as fellows:
At each of both the !fret and top stories, not less than two per
wall line ar line of wall elements providing a o~ line of
resistance to'. lateral forces. At each of all other stories, not
less than one per wall ele®ents pr+ovidirfg a oa~mbn line of
resistance to lateral forces. lh any case, not less than one per
1500 squaw feet of wall surface and a fatal of eight. The shear
tests shall be taken at locations representative of the mortar
conditions througksout the entire building, taking into aooannt
variations in workmanship at different building height levels,
ORDINANt~ 1531 .
Page -8-
2. Ns~ber ar+e location of testa (coat rn~~~
variations in weathering of the exterior surfao~, arxi variations
in the condition oP the interior surfaces due to deterioration
caused by leaks and condensation oP water and/or by the
deleterious effects of other substances oaltained within }~
building -dlexe the higher tyt ratios allowed in faotrates 4 arri
5 of Table Al-F are to be utilized, all the in-place st:ear tests
taken at the tap story shall be irrluded in the 80 peroetlt o! the
shear tests used to determine the miniaaan mortar shear strrmxlth.
the exact test locations shall be cetsrmined at the building site
build person responsible Por the seismic analysis of the subject
3. Zh~laos shear tests: 4he bed joint o! the outer wythe o! the
maeanty wall shall be tested in shear by laterally displacing a single
brick relative to the adjaoerlt bricks in the wythe. ~e opposite head
joint of the brick to be tested shall be removed arld cleaned prior to
testing. ~ minimum quality mortar in 8o percent of the shear tests shall
not be less than the total of 30 psi plus the axial stress in the wall at
the point of the test. the shear stress shall be based on the gross area
o! both bed joints and shall be that at which movement oP the brick is
fit'st observed.
(e) Testi.ra Shear Holts~ q~e-fourth of all new shear bolts and dow~als
embedded in unreinforced masonry walls shall be tested by a special
inspector' using a toryua calibrated wrench to the following minim
torques:
1/2-inch diameter bolts or dowels ~ 40 foot-~po~a~ds
5/8-inch diammter bolts ar dowels ~ 50 foot-po~aYls
3/4-inch cliaaieter bolts or dowels ~ 60 foot-po~usds
No bolts esaceedirg 3/4-irrh diameter shall be sued. Ail rafts shall be
installed wen malleable iron or place washers when bearing an wood and
heavy cut washers when bearing orr steel.
(f) netp*_TMi+,at{on of Allr,.~t,lp Stresses for Design -+~ Based on
Vest Results. -
1. Desicm sh~,r values. Design seismic in-plans shear stresses shall
be substantiated by tests perfozmed as specified in Item No. 3 of
Subsection (d).
Design stresses shall be related to test results obtained in
acool,iance with Table No. Al-I. Intent-ediate values between 5 and 10
psi may be irrtetpolated.
2. Desicm ornamesslon and tension valves Ooa~Z+ession stresses far
tnsreinfareed masonuy having a minim~na design shear value of 3
unreinforoed rnnsonzy shall not be permitted.
OFDI2~NCE 1531 •
Page -4-
(g) EJcistira Wall Anchors: Five percent of the existiriq wall arrhois
utilized as all or part of the required wall anchors shall be tested in
Pullout by an ap~prcnred testing a4~Y. The mininara number tested shall be
four. par floss, with two tests at walls with joist parallel to the wall.
Zhe test apparatus shall be supported on the masonry wall at a 7tiniinm~
distance equal to the wall thickness from the anchor tested. 'Ihe rvd
anchor shall be given a preload of 300 pounds prior to establishing a
datum for reoon3iz~g elorx3aticn. Tee tension test load reported shall be
recorded at 1/8-irrh relative movement of the anc3wr aril 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 oP the existing anchors shall
be forty percent of the average of those tested anchors having the same
wall thicla~ess and joist orientation.
(h) Qualification Tests: Qualificatioa:s tests far I~ devices used
far wall and~orage shall be tested with the entire tension load carried on
the enlarged head at the exterior fans of the wall. Hoed ort the part of
the device between enlarged head and the interior wall face shall be
eliminated for the qualification tests. The resistarre value assigned the
device shall be twenty percent oP the average of the ultimate load..
16.60.050 - 17JFC7[3~TION RDO(T.g2ID ON PLAN9
(a) Gen Yale .t in additiar to the seisnic analysis r~equ.ired in this
Qrdinaaoe, the person responsible Pon the seitaaic analysis of the building
shall determine and record the infozmation required by this section o~n the
approved plans.
(b) Construction Details. 4he following requirei~nts with apPr~apri,ate
oonstzvcticn details shall be made ea pert of the apPrnved plane.
1. A11 u:n^einforosd nasauy walls shall be andsored at the roof aM
ceiling with tension bolts thraxQi the wall or by existing rod
anchors at a maximum and~or spacing of six fast. All existing rod
anchors shall be secured to the joists to develop the required
lo~roes. Teats conforming to this ordinance will be required to
verify the adequacy of the embedded ends o! existing rod anchors.
EXQF.Pi'IC4~i: walls Hasa not be e:x3~ared to ceiling that,
because of their low mass and ar relative location with respect
to the floor ar rvof systems, would not impose significant normal
forces on the wall aM cause aut-of-plane wall failure,
Calculatioc:s and drawings to verify this exception aunt be
sutmitted as part of the analysis. At the root and all Hoar
levels, the ~enc~ors nearest the building corners shall be
combination shear and tension anchors located not more than two
feet horizontally fmn the inside corners of the walls.
Nhen access to the exterior face of the maso¢uy wall is prevented
by proximity o! an existing building, wall anc3iars conforming to
Items 5 (a) ar (b) in Table No. Al-H may be used.
ORDIHIiNCE 1531 • •
Page -lo-
mzTa~r Fmovgzm oN PLANS toontinueal
Alternative devices to be used in lieu of tensirn bolts far masonry
wall ar>chorage shall be tested as specified in Section 16.60.040(h).
2. Diaphracpa oord stresses of horizontal ~!ap!+ ~ shall be asveloped in
existing materials ar by the addition of new materials.
3. tasere trusses and beams other than rafters ar joists era supported an
masonry independent seoardary oolumna shall be installed to support
vertical loads.
,., .,~s...~..-.~.~... _ ,.
• .. ~.t .~.,~w.~ _
4. Parapets std exterior wall appendages not Capable of resisting the
fords specified in this Ordinance shall be removed, stabilized, our. braced
to e:rsttrg that the parapets and appendages remain in their original
position. The maximmi height of an unbiaoed, unrBinforoed masonry parapet
above. the lower of either tre level of tension anchors ar roof sheathing,
shall not exceed one and ~e-ha1E times the thickness of the parapet well.
Z! the required Parapet height exceeds this maxiimnn height, a bracing
systm~ designed for the Force factors specified in the Table 23~T of the
1985 Uniform Building Coda shall support the top of the parapet.. Parapet
correC;tive work must be performed in conjunction with the installation of
tensiari roof arx^hors. The miniaa>na height of a parapet above the wall
anchor shall be 12 inches.
Zf a reinforced concrete beam is provided at the top of the
wall, the minimum height above the wall anc3~or may be six inches.
5. All deteriorated mortar joints in tuireinforced aasotsry walls shall be
pointed with type S ar N mortar. Friar to any poitttitg, the wall surface
must be raked and cleaned to rmowe loose and deteriorated mortar. ALl
preparation and pointing shall be done under the oontinuaLS inspection of
as special. inspector. At the oonclusian of the project, the inspector
shall submit a written report to the Building Official setting forth the
portion of work inspected.
6. Repair details far any cracked ar datt~aged urueinfor~oed masonry wall
required to resist forces specified in this Ordirsanon.
(c) sBxi.~nq Construction: zhe Fallowing existing construction
info~rmati,ott shall bn made part of the appmoved plans:
1. The type std dimensions oP existing walls and the size and spacing
of floor std roof met~ezs.
2. The extent and type of existing wall arid~orage to floors and zcof.
3. the extent and type oP any parapet bracing ar other stxuctuial
reinforceznenYt to parts ar portions of the building which were previously
perfoxm®d.
ORDINANCE 1531 ~ •
Page -11-
4. Aoarrately dimensia~d floor plans aryl masonry wail elevation3
showing dimensioned opening, pieta, wall thicJmess and heights, vm~eer
locations and existing arrhorages.
5. Zha locations of cracks ar other damaged portions of tmraintar+ced
6. 'Ihe type of interiar wall surtaoes and ceilings, and i!
rein~tallirg ar arrhoring of existing plaster is naopssary.
7. The general onnciitian of the mortar joints aryl if the joints need
~~~m•
e. The location of all ir:-place shoat tests ar aa~re tests, shall be
ehawn on the floor plans and building wall elevations.
(a) The recd+i r,amwnra of this section are 1r1 addition to the
other analysis requis+aaeirts of this Ordinance. the relative stiffness and
sstrer~gth of a diaphragm governs the amount o! amplification of the seismic
grauxl moticn by the diaphragm, and therefore, a diaphragm stiffness and
strength tfllated check of the art-of-piano stability o! w~rainforoed
rags au~ walls arx~aored to mood diaphragtos shall be wade. his section
prooechu~a far evaluation of the out-of~lane stability of
unreinforoed mascauy walls arrhored to wood diaphragms that era coupled to
shear resisting eleaiertts.
(b) Definitions: The following definitions are applicable to this section:
Crow Wall: A wood framed wall having a height to length ratio
oomplyirq with Section 4713 (d) ar table 25-I of the 1985 Uniform
Building Code, and sheathed with any of the materials described in
Table A1~7 ar Tabla Al-K. ~e total strar-gtll of all cross walls
located within any 40 feat length of diaphragm meastmed in the
direction of the diaphragm span shall not be lass than 30 per~rt o!
the strength of the diaphagm in the direction of consideration.
Demarrl Cariacity Ratio (DQ21: A ratio of the following:
1. Demand equals the lateral foroea due to 33 percent of the
oombir>ad weight of the diaphragms and the tributary weight o! the
walls aryl other elements anchored to the diaphragm.
2. Capacity equals the diaphrac~s total shear atrerx3ttr in the
direction under oaresideration as determined using the values in
Tables No. A1~T ar Table Al-K.
ORDItU,NCE 1531 • .
Page -12-
(c) Notations•
j? s Depth of dinptsrac~n„ in Peet, measured pezperdicular to the
diaphragm span.
~ - height-to-thiclc~ess o! an urneinforoad mesaruy wall. Zhe
heic~t shall be measured between wall and:oraga levels and
the thiGa:ess shall be measured throtir~h the wall cross
section at the level ruder aaa:sideratian.
y - span o! diaphragm between masonry shear walls ar steel
Yrames.
yg ~ total shear capacity of cross walls in the direction of
analysis imaediataly below .the diaphracpn level being
. investigated es determined by using Tables No. A1~7 and
Al-K.
y~} - maximum shear strength in pounds per foot far a diaphracpn
sheathed with any of the materials given in tables No. Al-J
and Al-K.
y~ - total dead load of the diaphragm plus the tributary weight
of the walls ar:chared to the diaptsracpn, the tributary
ceiling and partitions and weight of any other permanent
building elements at the diaphragm level under
oonsideraticn.
(d) Design Check Pzvicedure.
1. C.enetal• Zhe demand capacity ratio (DCR) far the building shall be
calculated using the following equations:
get - 0.33 ~ L ~ vy D For building without cross walls
g$ . (~ c~ L ~ yy~ p + yg For building with cross walls
2. Di Deflection: The calculated DC4t shall be to the left of the
curve in Figure No. Al-L. F4:ere the calculated DCR is outside (to the
right ot) the curve, the diaphragm deflectica: limits are e~cceeded and
cross walls may be used to reduce the deflection.
3. Unreinforred Masanrv Wall Out-of-Plane Stability: 21~e DQ2 shall be
calculated discounting any cross wall. If the DCR Isom this method
~ to the diaphragm span is to the right of the anrve in Figure
No. Al-L, the region within the curve at anci below the intei~eectian of the
diaphragm span with the curve may ba used to determine the allowable k~/t
valves per Table No. Al-F.
CStDINANCE 1531 ~ .
Page -13-
TABLE NO. Al-F
AIiDi~ffiE VAIIJE OF HEIGHi~RfIIQINFS.S (k~/t) RATIO
OF i]I1REII MASOI~4tY 4k1LL~s WITfi MINB~4M QC~I.iTY I+DIiTAR
SJJIIDIIJGS WIZH ALL OTFffR
oOMPLYING C,EiOSS {~ALIB _
One Start w,iidirg Walls ~ - 16 Z ~ 4 13
First Start' of
Multi-Story Buildings 16 _ 15
Walls in the Top Start'
of Multi-start' Buildings ~ - 14 Z ~ 4 9
All Other Walls 16 13
l Mininaan mortal quality shall ba datazmined by laboratory tasting in
accordance with this Ordinance.
~ The minims mortar shear strengths s~equired in the following footr~otes
4 and 5 shall be that shear strecx~th without the affect Of axial
stress sin the wall at the point of the fast.
~ The larger heic,~zt~to-thiola~ess ratio may be used where nn~tar shear
tests in aaoozsianoe .with Section A7 (d) ~~~~ sh a minimmi mortar
shear strength of not less than 100 psi or where the tested mortar
shear strength is not less than 6o psi and as visual of
tha vertical wytlsa-to-wytha wall ;Dint (collar joint) irxiicates nat
less than 50 pet~oertt mortar coverage.
4 Where a visual e~nination of the Dollar joint indicates not less than
50 percent mortar oovarige and the minimm mortar shear strength when
established i11 eccoZdanoe with Section A7 (d) is greater than 30 psi
rut less than 60 psi, the allowable height~ro-~thicla~ess ratio may be
detezmined by linear interpolation batwean the larger and smaller
ratio values in dix+ecst pzvportion to the mortar shear strength.
ORDID~NCE 1531 • •
Page -14-
TAH1E NO. A1-G
VAII~4 FCR F~Q3I'ING MATF1ilPrLS (1)
1.
a. Roots with straight Sheathing
with thB roof covering applied 100 PLF tar sei~ain_~ar.
directly to the Sheathing. ~,,,,w....o~..~,.~-.w,,C.<
b. Roots with dia'gor~al sheathirq
with the root covering applied 400 PtF tar Seismic shear.
directly to the Sheathing.
c, Floors with straight tcxz~ae and i50 PLF far Seismic shear.
grows Sheathing.
d. Floors with straight Sheathing 300 PLF far seimnic shear.
and Finished wood floarirg.
e. Floors with diagonal Sheathing 450 PiF for seismic shear.
and finished wood floori~.
f. Floors ar mots with straight Add 50 PIF to the allowable
~~TxJ and Fd~~ aPP~ed values in items la and lc.
2.
Wood stud walls with lath and 100 PLF tar earn Bide far
Pl~~' seismic shear.
3. Plain Cbtxxste Footisfgs r'c ~ 1500 psi wzless a
othetwiae shown by tests.
4. Douglas Fir Wood Same as 1'985 uHC values !ar
No. 1 Douglas Fir. (3)
5. RSinforcing Steel f'c ~ 18,000 psi maximum, (3)
6. Structural Steel t'c ~ 20,000 psi n~axim<mi. (3)
(1) Material must be Sound and in good condition
(2) Wood lath and plaster must be reattadsed to existing joists ar ratters
in a manner approved by the Building official
(3) Stzesses given may be inc[+eased far cmibinations of loads as specified
in Section A6.
OQ2DINANCE 1531 •
Page -15-
. TABIE NO. Al-H
ALZAFAffiE VAIZ7F5 OF NEW MATg2IAI8 USID
IN Qxi7fRJCPIdN WiZH F3QST.II~IG IOPI
New Materials ar cbnfigutatian Allowable Values
of Materials
1.
Plywood sheathing applied directly
over exi8tinq straight sheathing Same as specified in Table
with ends of plywood sheets bearing 25,7 of the Uniform Building
o~n joists or rafters and edges of Building code far blocked
plywood located an center of diaphragms.
individual sheathing boards.
2. ,$bear Walls
a. Plywood sheathing applied directly
over existing wood studs. (No value Same as values specified in
shall be given to plywood applied Table No. 25-FQ, of the 1985
aver existing plaster ar wood ~ far shear walls.
b. Dry wall ar plaster applied 75 percent of the values
directly over existing woad etude specified in Table No. 47-I
of the 1988 L~C=
c. Dry wall ar plaster applied to One-third of the values
plywood sheathing aver wood studs specified in Table No. d7-I
o! the 1985 ~,,
3. Shear Bolts
Sheer bolts aril shear dowels 133 pez+oent of the values for
eeabedded a minimum of a irrh~ea plain masonuy specified in
into w~reinfoxcecl masonry walls. Table No. ~4Z7 0! the ~9 ~
Holt oentez+ed in a 2-1/2 inch 1~L No values larger than
d1 amnter hale With dL]T-paClC ar thOBe QiV@r fOT 3~4 11Y:~1
non shrink 4~t aruard the diameter bolts shall be used.
cir~amtferenoe of the bolt (1) (3)
4. Tension Holts
Tension bolts and tension dowels
M Y h URFt
walls secured with bearing plates
on far side of wall with at least
30 square irrhea of area. (2)
5. Oanbinatian Shear and Tension
a. Bolts ext.~+.rding to the exteriar
.fans of the wall with a 2-1/2
inch surd plate order the head.
Install as specified for shear
bolts. Spaced not closer than
12 irrhes an center (1) (2) (3)
ORDINANCE 1531
Pages -16-
5. Canbination Shear and Zhnsiop
wall Anchors. (oontirnredl
b. Bolts ar dowels eocterxiirrg to
the exterior face of the wall
with a 2-l,/2 irsch roturl plate
under the head aryl drill at an
angle of 22-1,/2 deyt+eea to the
horizontal. install as specified
tar shear bolts. (1) (2) (3)
1200 lbs. per bolt ar dowel
for t~sicn(4). See Item 3 far
shear Values.
c. Zhzwgtr bolt with bearing plate
for ternsicrr par Item 4.
(xmbined with minimum 8 irxii
clrotrted section for shear par
Item 3.
See Item 4 (Termion Holta)
for tension values(4). Sea
It® 3 far shear values.
6. Infilled Walls
R.einforoed masonry infilled openings Same as values specified !ar
in a+riatir~ unreinforcad masonry unreinfarrsd masaarty wall:
walls with keys ar dowels to match in this cfiapter.
reinforcing.
7. Reinforced Masonry
Masonry Piers aril walls reinforced Same as values specified in
as specified iriCxraptar 24 of the Tables No. 24-B oP the 1985
Uniform Buildirq Code. Uniform Building Oode.
8.
Ca~Crete footings, walls and pieta Sar1 as values specified in
reinforced as specified in Q~apter Q~apter 26 of the 1985
26 arxl designed far tributary loads. Unifo~zat Huildirg Code
9.
Foundation loads Pot structures Calculated existing foundatiar
exhibiting ra eviderrca of settlement loads dues to maximum dead load
plus live load may be increased by
25 percent aryl may be increased 50
percent far dead load plus sai.s:nic
loads zequired by this drapter.
(i) Holts aryl dowels to be tested as specified in Section A107.
(2) Bolts aryl dowels to be l,/2-inch dimneter mininana.
(3) Drilling for bolts and dowels shall be done with an electric rotary
drill. Impact tools shall not be used !ar drilling holes ar tic3trtenirg
anchor and shear bolt nuts.
(4) Allowable bolt and dowel values specified era far installations in
miniuaIIa three wyths wall. Far irrstallatians in two wythq walls uses 50
peroerrt o! the value specified, exvept that no value shall be given to
tansian bolts that do not extend entirely thnxx~s the wall and ors eacvred
with bearing plates car the far side.
ClE2DIPU~N(S 1531 , •
Page -17-
TAHSE N0. Al-I
ALSrOFU~HiE &F~AR 3IRY~,S FC82 TES'I~9
Sfff9~t TF9I5
80 ~ or test results Avg.tast result o! Seifnnic in-p1At~e shear in
in psi not less than: Domes in psi psi based on gross area*
30 plus axial stress 20 3
40 plus axial stress 27 4
50 plu8 axial stress 33 5
100 plus axial stress 67 ar more 10 (re.,.+,~, ^ ^ . .
*Allowable shear stress may be irxx+sased by additioai of 10 pernent of
axial stress due to the weicRit of the wall directlv~ig
_~~~
AI~OF~ffiE VALUES F+OR E}~STIIJG MATfItiAIS ZU ~ USID OIJLY Iri 'IHE
OQ~[IPATION OF ~ D'#r'8-ND CAPAiGPPY RATIO DESIGN (~~CZC
E~dstina Materials ar
Configuration of Materials Allowable Values
1. Horizontal Dim
a. Roofs with straight sheathing 100 lbs. per foot far
and roofing applied directly seismic shear.
to the sheathing.
b. Roofs with diagonal sheathing 250 ]bs. per foot far
and roofing applied directly seismic shear.
to the sheathing.
2. Crass Walls (2) Pier Side•
a. Plaster on wood ar metal lath.. 200 lbs.~per foot !ar
seismic shear.
b. Plaster an gypsum lath 175 lbs. per Foot for
seismic shear.
c. Gypsum wall board unbloGaed 75 lbs. per foot far
edges. seismic shear.
d. G7'P~ wall board blocked 125 lbs. per Post far
edges. seismic shear.
(i) Materials must be sotmd and in good condition.
(2) Fbr carves walls, values of all materials may be eca~bined, esacept the
total combined value shall not exceed 300 lbs. per foot for seismic
shear.
ORDINANCE 1531
Page -18-
New Mata*'iats or m„fim,.~,ti~,
of New acid i i.,e ~ eri„ta rig
811~b1a Values -
1.
a. Plywood sheathing applied
directly over existing straight
sheathing with ends o! plysaod 228 lbs. per foal !ar
seismic shear
sheets beating art rafters and .
~ of P1Y~d located an the
center o! individual sheathing
boards.
2. ~s Walls (2)
a. Plywood sheathing applied directly
over existing wood studs. No
value shall be given to plywood 1.33 titoes the Values
specified isr Table 25 K
wood sheathing~~ Plaster ar of the ~ UBC.
b. Drywall ar plaster applied
directly over WO0'a studs. 100 p went o! the values
specified in 'Table 47-I of
the 1985 UHC.
(1) Materials ,must be sound and in good cartdition.
(2) For cross walls, values of all materials may be oc>mbined, e~roent the
total combined shear value shall not e~aoeed 300 lbs. per foot Par
seismic stre~ar.
ORDINACIC3; 1531
Page -19-
54
E•
m
w
°' 300
z
M
2
d
vai 240
S
C9
6
a
2
e 180
N
Q
480
O
420
_ O O
360
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
0 1 2 3 4 5 6
DEMAND/CAPACITY RATIO - 0.33Wd / 2wD OR 0.33Wd / (2vuD.+,Vc)
FIGURE Al-L
ORDIN]4fJ(~ 1531
Page -20-
Zhe Building Official shall issue a Cc'ag~lianoe Ostler to the }auildirq owner
when it is determined that the build.inq is of unreinforced aiasoruy.
16,60.070
Within ens year fmn date of iasuanoe of Ckmplianoe Order, the building
owner shall submit to the City a stnu~aai analysis and plans for the
strerx3thenitg of the ty, t i ding Zhe planes mast be prepared by a licensed
struchuai/civil engineer ar ari3iitect. 4he permit application process
will be initiated at this time.
Within two years frvn data of Building Official's Oca~lianpe Older, all
corrective actions shall be oc~leted for full oomp].ianoe.
should the owner fail in meeting the crnditions of the Building Official's
OOtficial mama require the entire ~{~,otment specified herein, ttse Building
the conditions of the ding ~ ~~ and remain suc3t ~~
O~liance Order are met.
this Ordinance will remain in full force and effect Pon a period of five
(5) years after its effective date: thereafter, this Ordinance will
autanatically be repealed without Bother action o! the City Colulcil.
at a regular meeting of the City Axuril this 7th day oP
Mav , 1990, and II1AiCPFD at a r+eiglllar meeting of the City Co~utcil
this 21st day o! May , 1990, by ~.he following vote:
Yes *+3 of t-~ City CoL~*+~+i
Ayes: Goldman, Koppel, Sorensen, Szabo, Rogers
Nees: None
Absent: None
Ahata{n% N..~e