Chapter 18.28 — UNREINFORCED MASONRY BUILDING HAZARD REDUCTION PROGRAM

It is found and declared in the event of a strong or moderate local earthquake, loss of life or serious injury may result from damage or collapse of unreinforced masonry buildings in the city. The purpose of this chapter is to promote public safety by establishing a set of structural repair standards to be used to strengthen unreinforced masonry buildings and require owners to make their buildings conform to those standards within a reasonable period of time. The provisions of this chapter are minimum standards for structural seismic resistance established primarily to reduce the risk of life loss or injury but will not necessarily prevent loss of life or injury or prevent earthquake damage to an existing building which complies with these standards. This seismic hazard reduction program is consistent with California Health and Safety Code Sections 19160 through 19168 and Government Code Sections 8875 through 8878 et seq. (Ord. 1419 § 1, (1990))

For purposes of this chapter the words and phrases set out in this section shall mean as follows.

"Bearing wall" means any wall supporting a floor or roof where the total superimposed load
exceeds 100 pounds per linear foot, or any unreinforced masonry wall supporting its own weight
when over six feet in height.

"Civil engineer" or "structural engineer" means a licensed civil or structural engineer registered
by the state pursuant to the rules and regulations of Title 16. Chapter 5 of the California
Administrative Code.

"Occupant load" means the total maximum number of occupants in the building determined
by either 1) Table 33-A of the Uniform Building Code or, 2) the actual maximum number of
occupants in the building as certified by the building owner and current tenants.

"Story" means that portion of a building included between the upper surface of any floor and
the upper surface of the floor next above, except that the topmost story shall be that portion of a
building included between the upper surface of the topmost floor and the ceiling or roof above.

"Unreinforced masonry building" means any building containing walls constructed wholly or
partially with any of the following materials and containing less than fifty percent of the
minimum area of reinforcing steel required by the 1985 Uniform Building Code Section 2407
(h) 4 B:

1. Unreinforced brick masonry;

2. Unreinforced concrete masonry;

3. Hollow clay tile;

4. Adobe or unburned clay masonry.
(Ord. 1419 § 1, (1990))

Applicability. All unreinforced masonry buildings identified by the city, except those used exclusively for residential purposes containing five or less living units. (Ord. 1419 § 1, (1990))

The owners of unreinforced masonry buildings determined to be within the scope of this chapter will be notified in writing by the chief building inspector according to the schedule set forth in Section 18.28.050(b). (Ord. 1419 § 1, (1990))

(a) Building Categories. Two categories of unreinforced masonry building are hereby established to define the minimum lateral forces to be used in their strengthening according to formula A-1-1.

1. High risk buildings are those which have two or more stories or maximum occupant
load of more than 100 regardless of the number of stories. High risk buildings also
include any structure with an unreinforced masonry parapet wall where the remainder
of the building does not contain unreinforced masonry walls.

2. Medium risk buildings are those one story buildings with a maximum occupant load
of one hundred or less.

(b) Implementation Schedule. The owners of all buildings within the scope of this chapter must
submit plans to obtain a building permit for the structural modifications necessary to meet
the minimum requirements of this chapter by January 1, 1995.

The owners of all buildings within the scope of this ordinance must complete construction
of those structural modifications by June 30, 1996.

Notices providing a copy of the ordinance and stating the schedule for owner action will be
sent to each building owner within 90 days of the effective date of the ordinance codified
in this chapter.
(Ord. 1419 § 1, (1990); Ord. 1423 § 1, (1990))

Extensions of the time periods set forth in Section 18.28.050(b) may be granted by the city council based upon economic hardship. A request for an extension must be received at least 90 days before the expiration of the time period affected. (Ord. 1419 § 1, (1990); Ord. 1423 § 3, (1990))

The procedures and engineering standards establishing a minimum level of structural strengthening required for all unreinforced masonry buildings within the scope of this chapter are set forth in Section 18.28.080 of this chapter. The Uniform Code for Building Conservation Appendix Chapter One only, published in 1985 by the International Conference of Building Officials, Whittier, California, with amendments is hereby adopted as a part of this ordinance and all references in Sections 18.28.080 through 18.28.117 are to that appendix. (Ord. 1419 § 1, (1990))

Section A102 is amended to read as follows:

Section A102. The requirements of this chapter shall apply to all buildings containing unreinforced masonry bearing walls.

Exception: This chapter shall not apply to a detached Group R, Division 3 Occupancy nor to a detached Group R, Division 1 Occupancy containing less than five dwelling units used solely for residential purposes. (Ord. 1419 § 1, (1990))

Section A103 is amended to read as follows:

Sec. A103. Alternate materials, designs and methods of construction may be approved by the Chief Building Inspector in accordance with this code. (Ord. 1419 § 1, (1990))

Section A105 is amended to read as follows:

Sec. A105. (a) General. A historic building may comply with the special provisions set forth in this chapter and the provisions of the State Historical Building Code.

(b) Archaic Materials. Allowable stresses for archaic materials not specified in this code shall be based on substantiating research data or engineering judgment with the approval of the Chief Building Inspector. (Ord. 1419 § 1, (1990))

(a) Section A106(a) through (d), (f)1 and (g)3 are amended to read as follows:

Sec. A106. (a) General. Every structure within the scope of this chapter shall be analyzed
and constructed to resist minimum total lateral seismic forces assumed to act
nonconcurrently in the direction of each of the main axes of the structure in accordance
with the following equation:

V = ZIKCSW (A1-1)

The value of KCS need not exceed but shall not be less than .100 for one story buildings
with less than 100 occupants; and need not exceed but must not be less than .133 for
one story buildings containing 100 or more occupants and buildings over one story above
grade. 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.

(b) Lateral Forces on Elements of Structures. Parts or portions of buildings shall be analyzed
and designed for lateral loads in accordance with Chapter 23 of the 1985 Uniform Building
Code but not less than the value from the following equation:

Fp = ICpSWp (A1-2)

For the provisions of this section, the product of IS shall equal 1.0. The value of Cp shall be
in accordance with Table 23-J of the 1985 Uniform Building Code. The value of Wp shall
be as defined in Chapter 23 of the 1985 Uniform Building Code.

Exception: Unreinforced masonry walls in buildings not required to be designed as an
essential facility may be designed in accordance with Section A107.

(c) Regulated Elements of Buildings. The elements of buildings required to be analyzed by this
chapter include: 1) Height-to-thickness ratio of masonry walls; 2) Tension bolts in bending;
3) In-plane shear stress; 4) Parapets; 5) Diaphragm stresses and diaphragm chords in floors
and roof.

(d) 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 the 1985 Uniform Building Code and the Formula (A1-2) of this code. Masonry walls
shall be anchored to all floors and roof to resist a minimum force of 200 pounds per linear
foot acting normal to the wall at the level of the floor or roof.

(f) Required Analysis. 1. General. Except as modified herein, the analysis and design relating
to the structural alteration of existing buildings within the scope of this chapter shall be in
accordance with the analysis specified in the 1985 Uniform Building Code. In addition the
compatibility of the roof diaphragm stiffness with the out-of-plane stability of the
unreinforced masonry bearing walls of the story immediately below the roof shall be
verified in accordance with the provisions of Section A109.

Exception: Buildings with rigid concrete or steel and concrete roof diaphragms shall use
the h/t values for all other buildings in Table A1-F.

(g) 3. Unreinforced masonry walls. In addition to the seismic forces required by this chapter,
unreinforced masonry walls shall be analyzed as specified in the 1985 Uniform Building
Code to withstand all vertical loads as specified in the Building Code. Such walls shall
meet the minimum requirements set forth in the Building Code.

Exception: When calculating shear or diagonal tension stresses due to seismic forces,
existing masonry shear walls may be designed to resist 1.0 times the required forces in lieu
of the 1.5 factor required by the Building Code.

No allowable tension stress will be permitted in unreinforced masonry walls. Walls not
capable of resisting the required design forces specified in this chapter shall be
strengthened or shall be removed and replaced.

Exceptions:

1. Unreinforced masonry walls in buildings not classified as an essential facility may be
analyzed in accordance with Section A107.

2. Unreinforced masonry walls which carry no design loads other than their own weight
may be considered veneer if they are adequately anchored to new supporting
elements.

Substantial changes in wall thickness or stiffness shall be considered in the analysis for out-of-plane and inplane wall stability, and the wall shall be restrained against
out-of-plane instability by anchorage and bracing to the roof or floor diaphragm in
accordance with Section A106(d).

Exception: Variations in wall stiffness caused by nominal openings such as windows and doors need not be considered. (Ord. 1419 § 1, (1990))

Section A107(b), (d) and (f) are amended to read as follows:

(b) Existing Materials. 1. Unreinforced masonry walls. Unreinforced masonry walls analyzed
in accordance with this chapter may provide vertical support for roof and floor construction
and resistance to lateral loads.

All units of both bearing and non-bearing walls shall be laid with full shoved mortar joints;
all head, bed and wall (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 fulllength headers shall not exceed 24 inches either 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.

Wythes of walls not bonded as described above shall be considered as veneer. The veneer
wythe shall not be included in the effective thickness used to calculate the height-to-
thickness ratio and the shear capacity of the wall.

Tension stresses due to seismic forces normal to the wall may be neglected if the wall
does not exceed the height-to-thickness ratio set forth in Table A1-F and the in-plane
shear stresses due to seismic loads set forth in Table A1-I. If the wall height-to-thickness
ratio exceeds the specified limit, the wall may be supported by vertical bracing members
designed to satisfy the requirements of the 1985 Uniform Building Code. 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 bracing members designed in accordance
with Section A106(b) of this chapter if the deflection at design loads is not less than one-
quarter nor more than one-third of the wall thickness at the level under consideration.

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,
whichever is less.

The wall height may be measured vertically to bracing elements other than a floor or roof.
Spacing of 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.

2. Veneer. Veneer shall be anchored with approved anchor ties, conforming to the
required design capacity specified in Section 3304(c) of the 1985 Uniform Building
Code, and placed at a maximum spacing of 24 inches.

Exception: Existing veneer anchor ties may be acceptable provided the ties are in good
condition and conform to the minimum size, maximum spacing and material requirements
as indicated below. The veneer anchor ties shall be corrugated galvanized iron strips not
less than one inch in width, eight inches in length and one-sixteenth of an inch in thickness
and shall be located and laid in every alternate course in the vertical height of the wall at a
spacing not to exceed 17 inches on center horizontally. As an alternate, the spacing may be
every fourth course vertically at a spacing not to exceed nine inches on center horizontally.

The existence and condition of existing veneer anchor ties shall be verified as follows:

1. An approved testing laboratory shall verify the location and spacing of the ties and
shall submit a report to the Chief Building Inspector for approval as a part of the
structural analysis.

2. The veneer in a selected area shall be removed to expose a representative sample of
ties (not less than four) for inspection by the Chief Building Inspector.

3. Existing roof, floors, walls, footings, and wood framing. Existing 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. A1-G.

(d) Minimum Acceptable Quality of Existing Unreinforced Masonry Walls. 1. 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. The quality of mortar in all
masonry walls shall be determined by performing in-place shear tests. The vertical wall
joint between wythes (collar joint) shall be inspected at each test location after the in-place
shear tests, and an estimate of the percentage of wythe to wythe mortar coverage shall be
reported along with the results of the in-place shear tests. Where the exterior face is veneer,
the type of veneer, its thickness and its bonding and/or ties to the structural wall masonry
shall also be reported.

Nothing shall prevent the 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
masonry cements shall not be used. All preparation and mortar pointing shall be done under
the continuous inspection of a special inspector.

At the conclusion of the inspection, the inspector shall submit a written report to the person
responsible for the seismic analysis of the building setting forth the results of the work
inspected. Such report shall be submitted to the Chief Building Inspector for approval
as part of the structural analysis. All testing shall be performed in accordance with the
requirements specified in this section by an approved agency. An accurate record of all
such tests and their location in the building shall be recorded and these results shall be
submitted to the Chief Building Inspector for approval as part of the structural analysis.

2. Number and location of tests. The minimum number of tests shall be as follows. At each of both the first and top stories, not less than two per wall line or line of wall
elements providing a common line of resistance to lateral forces. At each of all other
stories, not less than one per wall element providing a common line of resistance to
lateral forces. In any case, not less than one per 1500 square feet of wall surface and
a total of eight.

The shear tests shall be taken at locations representative of the mortar conditions
throughout the entire building, taking into account variations in workmanship at
different building height levels, variations in weathering of the exterior surfaces, and
variations in the condition of the interior surfaces due to deterioration caused by
leaks and condensation of water and/or by the deleterious effects of other substances
contained within the building.

Where the higher h/t ratios allowed in footnotes 4 and 5 of Table A1-F are to be
utilized, all the in-place shear tests taken at the top story shall be included in the 80
percent of the shear tests used to determine the minimum mortar shear strength. The
exact test locations shall be determined at the building site by the person responsible
for the seismic analysis of the subject building.

3. In-place shear tests. The bed joint of the outer wythe of the masonry wall shall be
tested by laterally displacing a single brick relative to the adjacent bricks in the wythe.
The head joint opposite the load end of the test brick shall be carefully excavated and
removed. The brick adjacent to the loaded end of the test brick shall be carefully
removed by sawing or drilling and excavating to provide space for a hydraulic ram
and steel loading blocks. Steel blocks the size of the end of the bricks shall be used
on each end of the ram and shall not contact the bed joints. The load shall be applied
horizontally in the plane of the wythe until either a crack can be seen or a slip occurs.
The strength of the mortar shall be calculated by dividing the load at the time of the
first crack or movement by the nominal gross area of the sum of the two bed joints.

(f) Determination of Allowable Stresses for Design Methods Based on Test Results. 1. Design
shear values. Design seismic in-plane shear stresses shall be substantiated by tests
performed as specified in Item No. 3 of Subsection (d). The minimum quality mortar in 80
percent of the tests shall not be less than the total of 30 psi when reduced to an equivalent
zero axial stress.

Design stresses shall be related to test results obtained in accordance with Table No. A1-I.
Intermediate values between 5 and 10 psi may be interpolated.
(Ord. 1419 § 1, (1990))

Section A108(b) and (c) are amended to read as follows:

(b) Construction Details. The following requirements with appropriate construction details
shall be made a part of the approved plans:

1. All unreinforced masonry walls shall be anchored at the roof and ceiling levels by
tension bolts through the wall as specified in Table A1-H, or by an approved
equivalent at a maximum anchor spacing of six feet.

All unreinforced masonry walls shall be anchored at all floors and ceiling with tension bolts through the wall or by existing rod anchors at a maximum anchor spacing of
six feet. All existing rod anchors shall be secured to the joists to develop the required
forces. Tests conforming to this chapter will be required to verify the adequacy of the
embedded ends of existing rod anchors.

Exception: Walls need not be anchored to ceiling systems that, because of their low
mass and or relative location with respect to the floor or roof systems, would not
impose significant normal forces on the wall and cause out-of-plane wall failure.
Calculations and drawings to verify this exception must be submitted as part of the
analysis.

At the roof and all floor levels, the anchors nearest the building corners shall be
combination shear and tension anchors located not more than two feet horizontally
from the inside corners of the walls.

When access to the exterior face of the masonry wall is prevented by proximity of an
existing building, wall anchors conforming to Items 5 (a) or (b) in Table No. A1-H
may be used.

Alternative devices to be used in lieu of tension bolts for masonry wall anchorage
shall be tested as specified in Section A107(h).

2. Diaphragm chord stresses of horizontal diaphragms shall be developed in existing
materials or by the addition of new materials.

3. Where trusses and beams other than rafters or joists are supported on masonry
independent secondary columns shall be installed to support vertical loads.

4. Parts and exterior wall appendages not capable of resisting the forces specified in this chapter shall be removed, stabilized, or braced to ensure that the parapets and appendages remain in their original position. The maximum height of an unbraced, unreinforced masonry parapet above the lower of either the level of tension anchors or roof sheathing, shall not exceed one and one-half times the thickness of the parapet wall. If the required parapet height exceeds this maximum height a bracing system designed for the force factors specified in the Table 23-J of the 1985 Uniform Building Code shall support the top of the parapet. Parapet corrective work must be performed in conjunction with the installation of tension roof anchors. The minimum height of a parapet above the wall anchor shall be 12 inches. Exception: If a reinforced concrete beam is provided at the top of the wall, the minimum height above the wall anchor may be six inches. 5. All deteriorated mortar joints in unreinforced masonry walls shall be pointed with Type S or N mortar. Prior to any pointing, the wall surface must 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. At the conclusion of the project, the inspector shall submit a written report to the Chief Building Inspector setting forth the portion of work inspected. 6. Repair details for any cracked or damaged unreinforced masonry wall required to resist forces specified in this chapter.

   (c) Existing Construction. The following existing construction information shall be made part of the approved plans: 1. The type and dimensions of existing walls and the size and spacing of floor and roof members. 2. The extent and type of existing wall anchorage to floors and roof. 3. The extent and type of any parapet bracing or other structural reinforcement to parts and portions of the building which were previously performed. 4. Accurately dimensioned floor plans and masonry wall elevations showing dimensioned opening, piers, wall thickness and heights, veneer locations and existing anchorages. 5. The locations of cracks or other damaged portions of unreinforced masonry walls requiring repair. 6. The type of interior wall surfaces and ceilings, and if reinstalling or anchoring of existing plaster is necessary.

5. The general condition of the mortar joints and if the joints need repointing.

   8. The location of all in-place shear tests shall be shown on the floor plans and building
   wall elevations.

   (Ord. 1419 § 1, (1990))

Section A109 is added to read as follows:

Design Check for Compatibility of Roof Diaphragm Stiffness to Unreinforced Masonry Wall
Out-of-Plane Stability.

Sec. A109

(a) General. The requirements of this section are in addition to the other analysis requirements
of this Chapter. The relative stiffness and strength of a diaphragm governs the amount of
amplification of the seismic ground motion by the diaphragm, and therefore, a diaphragm
stiffness and strength related check of the out-of-plane stability of unreinforced masonry
walls anchored to wood diaphragms shall be made. This section contains a procedure for
evaluation of the out-of-plane stability of unreinforced masonry walls anchored to wood
diaphragms that are coupled to shear resisting elements.

(b) Definitions. The following definitions are applicable to this section.

Cross Wall. A wood framed wall having a height to length ratio complying with Section
4713(d) or Table 25-I of the 1985 Uniform Building Code and sheathed with any of the
materials described in Table A1-J or Table A1-K. 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 of
consideration.

Demand Capacity Ratio (DCR). A ratio of the following:

1. Demand equals the lateral forces due to 33 percent of the combined weight of the
diaphragm and the tributary weight of the wall and other elements anchored to the
diaphragm.

2. Capacity equals the diaphragm total shear strength in the direction under
consideration as determined using the values in Tables No. A1-J or Table A1-K.

(c) Notations.

D = depth of diaphragm, in feet, measured perpendicular to the diaphragm span.

h/t = height-to-thickness 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 frames.

Vc = total shear capacity of cross walls in the direction of analysis immediately below the
diaphragm level being investigated as determined by using Tables No. A1-J and A1-K.

vu = maximum shear strength in pounds per foot for a diaphragm sheathed with any of the
materials given in Tables No. A1-J or A1-K.

Wd = total dead load of the diaphragm plus the tributary weight of the walls anchored to the diaphragm, the tributary ceiling and partitions and weight of any other permanent building elements at the diaphragm level under consideration.

(d) Design Check Procedure.

1. General. The demand capacity ratio (DCR) for the building shall be calculated using
the following equations:

DCR = 0.33 Wd / 2vu D For building without cross walls or

DCR = 0.33 Wd / 2vu D + Vc For building with cross walls

2. Diaphragm Deflection. The calculated DCR shall be to the left of the curve in Figure
No. A1-L. Where the calculated DCR is outside (to the right of) the curve, the
diaphragm deflection limits are exceeded and cross walls may be used to reduce the
deflection.

3. Unreinforced Masonry Wall Out-of-Plane Stability. The DCR shall be calculated
discounting any cross wall. If the DCR from this method corresponding to the
diaphragm span is to the right of the curve in Figure No. A1-L, 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 No. A1-F.
(Ord. 1419 § 1, (1990))

Tables No. A1-A, A1-B, A1-C, A1-D and A1-E are deleted and Tables A1-F and A1-H are amended to read as follows:

TABLE NO. A1-F
ALLOWABLE VALUE OF HEIGHT-THICKNESS (h/t) RATIO OF
UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR 12

BUILDINGS WITH
COMPLYING CROSS
WALLS ALL OTHER BUILDINGS

345 One Story Building Walls 13 13 — 16

First Story of Multi-Story 16 15
Buildings

345 Walls in the Top Story of 9 9 — 14
Multi-Story Buildings

All Other Walls 16 13

1 Minimum mortar quality shall be determined by laboratory testing in accordance with this
chapter.

2 This table is not applicable to buildings classified as essential facilities. Such building
must be analyzed in accordance with Section A106.

3 The minimum mortar shear strengths required in the following footnotes 4 and 5 shall be
that shear strength without the effect of axial stress in the wall at the point of the test.

4 The larger height-to-thickness ratio may be used where mortar shear tests in accordance
with Section A107(d) establish a minimum mortar shear strength of not less than 100 psi
or where the tested mortar shear strength is not less then 60 psi and a visual examination
of the vertical wythe-to-wythe wall joint (collar joint) indicates not less than 50 percent
mortar coverage.

5 Where a visual examination of the collar joint indicates not less than 50 percent mortar
coverage and the minimum mortar shear strength when established in accordance with
Section A107(d) is greater than 30 psi but less than 60 psi, the allowable height-to-
thickness ratio may be determined by linear interpolation between the larger and smaller
ratio values in direct proportion to the mortar shear strength.

TABLES NO. A1-H
ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH
EXISTING CONSTRUCTION

New Materials or Configuration of
Materials 1 Allowable Values

1.  Horizontal Diaphragms Same as specified in Table 25-J of the 1985 Plywood sheathing applied directly over Uniform Building Code for blocked existing straight sheathing with ends of diaphragms. plywood sheets bearing on joists or rafters and edges of plywood located within the center 1/3 of individual sheathing boards.

2.  Shear Walls Same as values specified in Table

TABLES NO. A1-H
ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH
EXISTING CONSTRUCTION

New Materials or Configuration of
Materials 1 Allowable Values

a.  Plywood sheathing applied directly over No. 25-K of the 1985 UBC for shear walls.
existing wood studs. (No value shall be given
to plywood applied over existing plaster or
wood sheathing boards).

b.  Dry wall or plaster applied directly over 75 percent of the values specified in Table
existing wood studs. No. 47-I of the 1985 UBC.

c.  Dry wall or plaster applied to plywood One-third of the values specified in Table No.
sheathing over wood studs. 47-I of the 1985 UBC.

3.  Shear Bolts 133 percent of the values for plain masonry
Shear bolts and shear dowels embedded a specified in Table No. 24-J of the 1985 UBC.
minimum of 8 inches into unreinforced No values larger than those given for 3/4 inch
masonry walls. Bolt centered in a 2-1/2 inch diameter bolts shall be used.
diameter hole with drypack or non-shrink
grout around the circumference of the bolt. 13

4.  Tension Bolts 1200 pounds per bolt.
Tension bolts and tension dowels extending
entirely through URM walls secured with
bearing plates on far side of wall with at least
30 square inches of area. 234

5.  Combination Shear and Tension Wall
Anchors

(a)  Bolts extending to the exterior face of 600 lbs. per bolt for tension 4. See Item 3
the wall with a 2-1/2 inch round plate under (Shear Bolts) for shear values.
the head. Install as specified for shear bolts.
Spaced not closer than 12 inches on centers. 123

(b)  Bolts or dowels extending to the exterior 1200 lbs. per bolt or dowel for tension 4. See
face of the wall with a 2-1/2 inch round plate Item 3 for shear values.
under the head and drill at an angle of 22-1/2
degrees to the horizontal. Install as specified
for shear bolts. 123

(c)  Through bolt with bearing plate for See Item 4 (Tension Bolts) for tension
tension per Item 4. Combined with minimum values 4. See Item 3 for shear values.
8 inch grouted section for shear per Item 3.

6.  Infilled Walls Same as values specified for unreinforced
Reinforced masonry infilled openings in masonry walls in this chapter.
existing unreinforced masonry walls with
keys or dowels to match reinforcing.

TABLES NO. A1-H
ALLOWABLE VALUES OF NEW MATERIALS USED IN CONJUNCTION WITH
EXISTING CONSTRUCTION

New Materials or Configuration of
Materials 1 Allowable Values

7.  Reinforced Masonry Same as values specified in Table No. 24-B of
Masonry piers and walls reinforced as the Uniform Building Code. 1985
specified in Chapter 24 of the 1985 Uniform
Building Code.

8.  Reinforced Concrete Same as values specified in Chapter 26 of the
Concrete footings, walls and piers reinforced 1985 Uniform Building Code
as specified in Chapter 26 and designed for
tributary loads.

9.  Existing Foundation Loads Calculated existing foundation loads due to
Foundation loads for structures exhibiting no maximum dead load plus live load may be
evidence of settlement. increased by 25 percent and may be increased
50 percent for dead load plus seismic loads
required by this chapter.

1 Bolts and dowels to be tested as specified in Section A107.

2 Bolts and dowels to be 1/2-inch diameter minimum.

3 Drilling for bolts and dowels shall be done with an electric rotary drill. Impact tools shall
not be used for drilling holes or tightening anchor and shear bolt nuts.

4 Allowable bolt and dowel values specified are for installations in minimum three wythe wall. For installations in two wythe walls use 50 percent of the value specified, except that no value shall be given to tension bolts that do not extend entirely through the wall and are secured with bearing plates on the far side.

(Ord. 1419 § 1, August 20, 1990)

Table Nos. A1-J and A1-K and Figure A1-L are added to read as follows:

TABLE NO. A1-J
ALLOWABLE VALUES FOR EXISTING MATERIALS TO BE USED ONLY IN THE
COMPUTATION OF THE DEMAND CAPACITY RATIO DESIGN CHECK

Existing Materials or Configuration of
Materials 1 Allowable Values

1.  Horizontal Diaphragms

a.  Roofs with straight sheathing and roofing 100 lbs.  per foot for seismic shear.
applied directly to the sheathing.

TABLE NO. A1-J
ALLOWABLE VALUES FOR EXISTING MATERIALS TO BE USED ONLY IN THE
COMPUTATION OF THE DEMAND CAPACITY RATIO DESIGN CHECK

Existing Materials or Configuration of
Materials 1 Allowable Values

b.  Roofs with diagonal sheathing and 250 lbs.  per foot for seismic shear.
roofing applied directly to the sheathing.

2 Per Side: 2.  Cross Walls

a.  Plaster on wood or metal lath. 200 lbs.  per foot for seismic shear.

b.  Plaster on gypsum lath. 175 lbs.  per foot for seismic shear.

c.  Gypsum wall board unblocked edges. 75 lbs.  per foot for seismic shear.

d.  Gypsum wall board blocked edges. 125 lbs.  per foot for seismic shear.

1 Materials must be sound and in good condition.

2 For cross walls, values of all materials may be combined, except the total combined value
shall not exceed 300 lbs. per foot for seismic shear.

TABLE NO. A1-K
ALLOWABLE VALUES FOR NEW MATERIALS USED IN CONJUNCTION WITH
EXISTING CONSTRUCTION MATERIALS TO BE USED ONLY IN THE
COMPUTATION OF THE DEMAND CAPACITY RATIO DESIGN CHECK

New Materials or Configuration of New
and Existing Materials 1 Allowable Values

1.  Horizontal Diaphragms

a.  Plywood sheathing applied directly over 225 lbs. per foot for seismic shear.
existing straight sheathing with ends of
plywood sheets bearing on rafters and edges
of plywood located on the center of individual
sheathing boards.

2.  Cross Walls

a.  Plywood sheathing applied directly over 1.33 times the values specified in Table 25-K
existing wood studs. No value shall be given of the 1985 UBC.
to plywood applied over existing plaster or
wood sheathing.

b.  Drywall or plaster applied directly over 100 percent of the values specified in Table existing wood studs. 47-I of the 1985 UBC.

1 Materials must be sound and in good condition.

2 For cross walls values of all materials may be combined, except the total combined shear
value shall not exceed 300 lbs. per foot for seismic shear.

FIGURE A1-L
1. Region of demand/capacity ratios where cross walls may be used to increase H/T ratios.
2. Region of demand/capacity ratios where H/T ratios of "with cross walls" may be used
whether or not they are present.
3. Region of demand/capacity ratios where H/T ratios of "all other buildings" must be used
even if cross walls are present.
Demand/capacity ratio = 0.33 Wd / 2 vuD or 0.33 Wd / 2 vuD + Vc.

(Ord. 1419 § 1, August 20, 1990)

It is unlawful for the owner of a building identified as being within the scope of this ordinance to fail to submit plans and obtain a permit for correction of structural deficiencies discovered, or fail to complete the necessary structural corrections within the time period specified in Section 18.28.050(b). The city may invoke all remedies available at law, including, but not limited to, the following.

(a) The city may revoke the building's certificate of occupancy and cause it to be vacated until such requirements are met.

(b) The city may seek injunctive relief on behalf of the public to enjoin a building owner's violation of this ordinance. (Ord. 1419 § 1, August 20, 1990)