Beaumont Municipal Code Ch. 15.42 Earthquake Hazard Reduction in Existing Unreinforced Masonry Bearing…

The purpose of this Chapter is to promote public safety and welfare by reducing the risk of death or injury that may result from the effects of earthquakes on unreinforced masonry bearing wall buildings. The provisions of this Chapter are intended as minimum standards for structural seismic resistance established primarily to reduce the risk of life loss or injury. Compliance with these standards will not necessarily prevent loss of life or injury or prevent earthquake damage to rehabilitated buildings. This Chapter does not require alteration of existing electrical, accessibility. plumbing, mechanical or fire safety systems unless they constitute a hazard to life or property.

(Ord. 695 §1, 1991)

The provisions of this Chapter shall apply to all existing buildings not exceeding two stories in height having at least one unreinforced bearing wall as defined herein.

Exceptions: This Chapter shall not apply to the following:

1. Buildings classified as essential facilities in Table No. 23-K, 1988 Uniform Building Code.

2. Buildings classified as hazardous facilities in Table No. 23-K, 1988 Uniform Building Code.

3. Detached dwellings.

4. Detached apartment houses containing less than five dwelling units which are used solely for residential purposes.

(Ord. 695, §1, 1991)

Alternate materials, designs and methods of construction may be approved by the Building Official in accordance with the 1988 Uniform Building Code.

(Ord. 695 §1, 1991)

For the purpose of this Chapter, certain terms are defined as follows:

Cross walls: Cross walls are interior walls of masonry or wood frame construction with surface finish of wood, lath and plaster, minimum one-half-inch thick gypsum wallboard of solid horizontal wood sheathing. In order to be considered as a cross wall within the intent of this Chapter, cross walls shall be spaced not more than 40 feet apart in each story, and shall be full story height with a minimum length of one and one-half times the story height.

Unreinforced masonry bearing wall building: A building containing a minimum of one wall having the following characteristics:

1. Provides the vertical support for a floor or roof.

2. The total superimposed load is over 100 pounds per linear foot.

3. The area of reinforcing steel, if any, is less than 50 percent of that required by section 2407(h)4B of the 1988 Uniform Building Code.

In an unreinforced masonry bearing wall building as defined above all unreinforced masonry walls (including non-bearing walls) shall be reinforced as per this Chapter.

(Ord. 695 §1, 1991)

A. Service of Order. The Building Official shall issue an order, as provided in Subsection B, to the owner of each building within the scope of this Chapter within one year from the effective date of this Chapter.

B. Contents of Order. The order shall be in writing and shall be served either personally or by certified or registered mail upon the owner. The order shall specify that the building has been determined by the Building Official to be within the scope of this Chapter and, therefore, is required to meet the minimum standards of this Chapter. The order shall specify the degree of compliance required by this Chapter and shall be accompanied by a copy of this Chapter and shall specify the time limits for compliance.

C. Appeal from Order. The owner or the owner's authorized agent may appeal to the Planning Commission the Building Official's initial determination that the building is within the scope of this Chapter. Such appeal shall be filed with the City Clerk within 60 days from the service date of the order described in Subsection B. Any such appeal shall be decided by the Planning Commission no later than 60 days after the date that the appeal is filed. Such appeal shall be made in writing upon appropriate forms provided therefore by the Building Official and the grounds thereof shall be stated clearly and concisely. Each appeal shall be accompanied by a filing fee as set forth by resolution of the City Council. Any person not satisfied with a determination by the Planning Commission may appeal said determination by the manner set forth in Section 17.70.200b, 7, 8, and 9 of the Beaumont Municipal Code.

Appeals or requests for modifications from any other determinations, orders, or action by the Building Official pursuant to this Chapter, shall be made in accordance with the appeal procedures established in Section 17.70.200b of this Code.

D. Recordation. At the time that the aforementioned order is served, the Building Official shall file with the Office of the County Recorder a certificate stating that the subject building is within the scope of Chapter 15.42, Earthquake Hazard Reduction in Existing Unreinforced Masonry Bearing Wall Buildings. The certificate shall also state that the owner thereof has been ordered to structurally analyze the building and to structurally alter or demolish it where it is not found to comply with this Chapter.

E. Termination of Status. If the building is found not be within the scope of this Chapter, or as a result of structural alterations or an analysis is found to be structurally capable of resisting minimum seismic forces required by this Chapter; or is demolished; the Building Official shall file with the Office of the County Recorder a certificate terminating the status of the subject building as being classified within the scope of this Chapter.

F. Enforcement. If the owner fails to comply with any order issued by the Building Official pursuant to this Chapter within any of the time limits set forth in Section 15.42.060, the Building Official shall order the entire building vacated and to remain vacated until such order has been complied with. If compliance with such order has not been accomplished within 90 days after the date the building has been ordered vacated, or by such additional time as may have been granted by the City Council, the Building Official may initiate proceedings in accordance with the Uniform Code for the Abatement of Dangerous Buildings.

(Ord. 695 §1, 1991)

A. General. Unreinforced masonry bearing wall buildings subject to this Chapter shall undergo structural alterations necessary to comply with the minimum requirements set forth in this Chapter. As an alternate, said buildings may be demolished subject to the requirements of the Uniform Building Code.

B. Mandatory Requirements.

1. Compliance with Standards. Unreinforced masonry buildings shall comply with provisions of this Chapter. Should an owner elect to strengthen a building beyond the mandatory requirements set forth herein, such additional strengthening work shall comply with other recognized standards as approved by the Building Official.

2. Change in Use. After the effective date of' this Chapter the time limits set forth in Table No. 15.42-A shall not apply to any building which will undergo a change of use or occupancy which will result in the building being classified as a Group A Occupancy having an occupant load of 100 or more. Before such building may be used or occupied as a Group A Occupancy it shall be made to comply with provisions of this Chapter.

C. Responsibility of Owner. The owner of each building within the scope of this Chapter shall cause a structural analysis of the building to be made by civil or structural engineer licensed by the State of California. If the building does not meet the minimum earthquake standards specified in this Chapter, the owner shall either cause it to be structurally altered to conform to such standards; or shall initiate proceedings for demolition of the building. Within 270 days after the service of the order specified in Section 15.42.050, the owner shall comply with the requirements set forth in this Subsection by submitting to the Building Official one of the following:

1. A structural analysis which shall demonstrate that the building meets the minimum requirements of this Chapter; or

2. A structural analysis and plans for proposed structural alterations necessary to make the building comply with the minimum requirements of this Chapter; or

3. An application for the demolition of the building.

After plans are submitted and approved by the Building Official, the owner shall obtain a building permit, commence and complete the required construction or demolition within the time limits set forth in Table No. 15.42-A.

(Ord. 695 §1, 1991)

A. Existing Materials. All existing materials utilized as part of the lateral force resisting system shall be in sound condition or shall be removed and replaced with new materials.

B. Existing Unreinforced Masonry.

1. General. Unreinforced masonry walls shall be tested as specified in this Subsection. Masonry that does not meet or exceed the minimum standards established by this Chapter shall be removed and replaced by new materials or shall have its structural functions replaced by new materials and anchored to supporting elements.

2. Lay-up Walls. The facing and backing shall be bonded so that not less than four percent of the wall surface of each face is composed of solid headers extending not less than four inches into the backing. The distance between adjacent full-length headers shall not exceed 24 inches either vertically or horizontally. In walls in which a single header does not extend through the wall, headers from 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 bounded as described above shall be considered as veneer. The veneer wythe shall not be included in the effective thickness used in calculating the height to thickness ratio of the wall unless it is bonded and anchored to the backing in a manner acceptable to the Building Official.

3. Mortar.

a. Tests. The quality of mortar in unreinforced masonry walls shall be determined by performing in place shear tests in accordance with Standard 15.42-1. Alternate methods of testing may be approved by the Building Official.

b. Location of Tests. Shear tests shall be taken at locations representative of the mortar conditions throughout the entire building. The exact test location shall be determined at the building site by the engineer in responsible charge of the structural design work. An accurate record of such tests and their location in the building shall be recorded and these results shall be submitted to the Building Official for approval as part of the structural analysis.

c. Number of Tests. The minimum number of tests per wall or line of wall elements providing a common line of resistance to lateral forces shall be as follows: Two tests per wall with a minimum total number of eight tests or one test per 1,500 square feet of wall area, whichever results in the greater number of tests.

d. Minimum Quality Mortar.

(i) Mortar shear test values, v to ' shall be obtained for each in-place shear test in accordance with the following equation:

v to = v test - PD+L lAW···················· (7-1)

WHERE:

V to = Mortar shear test value, in psi.

V test = Shear stress at incipient cracking for each in-place test per Standard to 15.42-1.

PD+L = Actual dead plus live load in place at the time of testing, pounds.

AW = Area of the wall supporting PD+L at each in-place shear test.

(ii) Individual unreinforced masonry walls with Vto less than 30 psi shall be pointed prior to retesting.

(iii) The mortar shear strength, Vto ' is the value in psi that is exceed by 80 percent of all of the mortar shear test values, Vto.

(iv) Unreinforced masonry with mortar shear strength, Vto ' less than 30 psi shall be removed or pointed and retested or treated as veneer.

C. Pointing. All deteriorated mortar joints in unreinforced masonry walls shall be pointed according to Standard No. 15.42-2. Nothing shall prevent pointing with mortar of all masonry wall joints before the tests are made.

(Ord. 695 §14, 1991)

A. Pointing. Special inspection shall be provided during preparation and mortar pointing.

B. Shear Tests. In-place shear tests shall comply with Section 15.42.070B and Standard 15.42-1.

C. Existing Floor Level Wall Anchors. If existing rod anchors are to be utilized as all or part of the required wall anchorage system at the floor level, not less than five percent of such existing rod anchors shall be tested by an approved testing laboratory. The minimum number of anchors tested shall be four per floor, with two tests at walls with joists framing into the wall and two tests at walls with joists parallel to the wall but not less than ten percent of the total number of existing tension anchors at each level. The test apparatus shall be supported on the masonry wall at a minimum distance of the wall thickness from the anchor tested. The rod anchor shall be given a preload of 300 pounds prior to establishing a datum for recording elongation. The tension test load reported shall be recorded at one-eighth inch relative movement of the anchor and the adjacent masonry surface. Results of all tests shall be reported. The report shall include the test results as related to the wall thickness and joint orientation. Ends of existing anchors shall be secured into the wood framing by an approved method.

D. Testing of Bolts. One-fourth of new embedded bolts in unreinforced masonry walls shall be tested by a special inspector using a torque calibrated wrench to the following minimum torques:

½" diameter bolts or dowels = 40 foot-lbs.

⅝" diameter bolts or dowels = 50 foot-lbs.

¾" diameter bolts or dowels = 60 foot-lbs.

No bolts exceeding ¾" diameter shall be used. Nuts shall be installed over malleable iron or cut plate washers when bearing on wood and heavy cut washers when bearing on steel.

(Ord. 695 §1, 1991)

A. Tension Anchors. Allowable values for tension anchors are given in Table No. 15.42-B. A one-third increase is not allowed for values listed in this Table.

B. Other Materials. Allowable values not specified in this Chapter shall be as specified elsewhere in the 1988 Uniform Building Code.

(Ord. 695 §1, 1991)

A. Lateral Force on Elements or Structures and Nonstructural Components. Parts or portions of structures, nonstructural components and their anchorage to the main structural system shall be designed for lateral forces in accordance with the following formula:

Fp = Cp Wp ···················· (10-1)

W shall be as defined in Section 2312(c) of the Uniform Building Code. The value of Cp need not exceed the values set forth in Table No. 15.42-C.

B. Height to Thickness Limitations. Unreinforced masonry wall height to thickness ratios shall not exceed the ratios set forth in Table No. 15.42-D. If a wall height to thickness ratio exceeds the specified limits, the wall shall be laterally supported by bracing members complying with Subsection C. 1 or with Subsection C.2 Bracing systems shall be designed in accordance with Section 15.42.100A.

C. Bracing Methods.

1. Vertical Bracing Members. vertical bracing members shall be attached to floor and roof construction for their design loads independent of required wall anchors. Horizontal spacing of vertical bracing members shall not exceed one-half the unsupported height of the wall nor ten feet. Deflection of such bracing members at design loads, as determined from Section 2312(g)2 (1988 Uniform building Code) and Formula (12-10), shall not exceed one-tenth of the wall thickness.

2. Wall Bracing. The wall height may be measured to bracing elements other than a floor or roof. Horizontal spacing of the bracing elements and wall anchors shall not exceed six feet on center nor six times the wall thickness, whichever is less. Bracing elements shall be detailed to minimize the horizontal displacement of the wall by the vertical displacement of the floor or roof.

D. Wall Anchorage.

1. Anchor Locations. Unreinforced masonry walls shall be anchored at the roof and floor levels and at vertical bracing members in order to resist the forces specified in this Section.

2. Wall Anchor Requirements. Wall anchors shall be tension bolts through the wall having a maximum spacing of six feet or six times the wall thickness, whichever is less. Alternate anchors shall be combination tension and shear bolts complying with the requirements set forth in Table No. 15.42-B. Tension bolts used to resist required forces may be assumed to develop the allowable values listed in Table No. 15.42-B. If access to the exterior face of a masonry wall is prevented by proximity of an existing building or when the appearance of 'through the wall tension anchors will affect the architectural appearance of the building, embedded bolts conforming to Table No. 15.42-B may be used. Wall anchors shall be secured to the rafters or joists to transfer the required forces into roof or floor sheathing.

3. Minimum Wall Anchorage Force. Anchorage of masonry walls to each floor or roof shall resist a minimum force determined by Formula (10-1) or 200 pounds per linear foot, whichever is greater, acting normal to the wall at the level of the floor or roof. Existing wall anchors installed under previous permits must meet or must be upgraded to meet the requirements of this Chapter.

4. Anchors at Corners. At the roof and floor levels, combination tension and shear anchors shall be provided within two feet horizontally from the inside of the corners of the walls.

E. Parapets. Parapets and exterior wall appendages not capable of resisting the forces specified in this Section shall be removed, stabilized or braced to insure that the parapets and appendages remain in their original position. The maximum height of an un-braced unreinforced masonry parapet above the level of tension anchors 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 determined by formula (10-1) shall be installed to support the parapet. Parapet corrective work shall be performed in conjunction with the installation of tension roof anchors. The maximum height of a parapet above the horizontal supports shall be 12 inches.

F. Veneer.

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

2. Veneer shall be anchored with approved anchor ties, conforming to the required design capacity specified in this Code and placed at a maximum spacing of 24 inches with a maximum supported area of two square feet.

Exception: Existing veneer anchor ties may be acceptable provided the ties are in good condition and conform to the following minimum size, maximum spacing and material requirements.

Existing 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 or equal and shall be located in every alternate course in the height of the wall at a spacing not to exceed 18 inches on centers horizontally. As a result, such ties may be laid in every fourth course vertically at a spacing not to exceed nine inches on centers horizontally.

3. The location and condition of existing veneer ties shall be verified as follows:

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

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

G. Mortar Joints. All deteriorated mortar joints in unreinforced masonry walls shall be pointed with Type S or N mortar. Masonry cements shall not be used. 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 continuous inspection by a special inspector certified to inspect masonry or concrete. At the conclusion of the project, the special inspector shall submit a written report to the Building Official setting forth the portion of the work inspected.

(Ord. 695 §1, 1991)

For Time Limits and Technical Specifications see Table Nos. 15.42-A, 15.42-B, 15.42-C, and 15.42-D; Standard Nos. 15.42-1 and 15.42-2:

TABLE NO. 15.42-A TIME LIMITS FOR COMPLIANCE (3)

(1) Measured from the date of the order.

(2) Measured from the date of building permit issuance.

(3) These time limits shall not apply to a change of occupancy involving a Group A Occupancy having an occupant load of 100 or more. See Section 15.42.060B2.

TABLE NO. 15.42-B ALLOWABLE VALUES FOR TENSION ANCHORS

(1) A one-third increase in allowable stresses is not allowed.

(2) Bolts to be ½-inch minimum in diameter.

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

TABLE NO. 15.42-C HORIZONTAL FORCE FACTOR "Cp" FOR PARTS OF PORTIONS OF BUILDINGS OR OTHER STRUCTURES

TABLE NO. 15.42-D ALLOWABLE VALUE OF HEIGHT-THICKNESS RATIO OF UNREINFORCED MASONRY WALLS WITH MINIMUM QUALITY MORTAR (1)

(1) Minimum quality mortar shall be determined by laboratory testing in accordance with Section 15.42.070B3.

STANDARD NO. 15.42-1 IN-PLACE MASONRY SHEAR TESTS

The bed joints of the outer wythe of the masonry shall be tested in shear by laterally displacing a single brick relative to the adjacent bricks in the same wythe. The head joint opposite the loaded end of the test brick shall be carefully excavated and cleared. 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 brick, shall be used on each end of the ram to distribute the load to the brick. The blocks shall not contact the mortar joints. The load shall be applied horizontally, in the plane of the wythe, until either a crack can be seen or slip occurs. The strength of the mortar shall be calculated by dividing the load at the first crack or movement of the test brick by the nominal gross area of the sum of the two bed joints.

STANDARD NO. 15.42-2 POINTING OF UNREINFORCED MASONRY WALLS

POINTING

The old mortar should be cut out, by means of a toothing chisel or a special painter's grinder, to a uniform depth of three-quarters inch (¾"), or until sound mortar is reached. Care must be taken not to damage the brick edges. All dust and debris must be removed from the joint by brushing, blowing air or rinsing with water.

Mortar mix shall be Type "5" or "N" proportions as called for in the construction specification. The tuck-pointing mortar should be pre-hydrated to reduce excessive shrinkage. The proper pre-hydration process is as follows:

All dry ingredients should be thoroughly mixed. Only enough clean water should be added to the dry mix to produce a damp, workable consistency which will retain its shape when formed into a ball. The mortar should stand in this dampened condition for one (1) to one and one-half (1½) hours.

The joints to be tuck-pointed should be dampened, but to ensure a good bond, the brickwork must absorb all surface water. Add water to the pre-hydrated mortar to bring it to a workable consistency which is somewhat drier than conventional mortar. The mortar should be packed tightly into the joints in thin layers not to exceed one-quarter inch (¼"). Each layer should become "thumbprint hard" before applying the next layer. The joints should be tooled to match the original profile after the last layer of mortar is "thumbprint hard".

RELAYING OF BRICK

Replacement bricks must match the originals with respect to size, color, and texture where exposed. A tuck-pointing toothing chisel should be used to cut out the mortar which surrounds the affected units. Power driven impact tools are not allowed. Once the units are removed, all of the old mortar shall be carefully chiseled out and all dust and debris shall be swept out with a brush. If used brick is to be relayed, it shall be cleaned of all old mortar. The brick surfaces in the wall shall be dampened before new units are placed, but the masonry should absorb all surface moisture to ensure a good bond. The appropriate surfaces of the surrounding brickwork and the replacement brick should be buttered with mortar. The replacement brick should be centered in the opening and pressed into position. The excess mortar should be removed with a trowel. Pointing around the replacement brick will help to ensure full head and bed joints. When the mortar becomes "thumbprint hard", the joints shall be tooled to match the original profile.

(Ord. 695 §1, 1991)