Lindsay Municipal Code § 15.05 Unreinforced Masonry Buildings

1. The purpose of this chapter is to promote public safety, health and welfare by reducing the risk of death or injury that may result from the effects of earthquakes on unreinforced masonry buildings.
2. The provisions of this chapter establishes minimum standards for structural seismic resistance primarily to reduce the risk of death or injury, but cannot prevent loss of life or injury or prevent earthquake damage to an existing building even though it complies with these standards.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

1. The provisions of these requirements shall apply to all buildings having unreinforced masonry bearing walls as defined herein. It is recognized that strengthening was done to some unreinforced masonry buildings following the 1952 Kern County earthquake. The engineer or architect retained by the building owner and the city building official shall give full consideration to any strengthening done when analyzing the existing condition of the building as required by this chapter. Where strengthening was done which may not fully comply with the provisions of this chapter, approval may be granted by the city building official if the building's condition complies with the intent of this chapter.
2. Nothing in this chapter shall prevent the building owner, his architect or engineer from employing accepted alternative methods to prove the minimum seismic safety of a building. In the event an alternative method is employed by the building owner, his architect or engineer which is not accepted by the city building official, the building owner shall have the right to appeal that decision to the board of building appeals.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

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

"Architect or engineer" means a California licensed architect or California licensed civil or structural engineer in responsible charge of the structural design work for the project.

"Cross walls" means interior walls of masonry or wood stud construction. In order to be considered as a cross wall within the intent of this chapter, cross walls shall be not more than forty feet apart in each story, and shall be full story height between diaphragms. Existing cross walls shall be a minimum length of one and one-half times the story height. Existing wood frame cross walls shall be sheathed with one of the following: wood lath and plaster, one-half inch thick gypsum wallboard on two sides, or solid one inch nominal thickness straight or diagonal wood board sheathing. New cross walls shall have a rational shear path to the ground, and shear values in Chapter 25 of the California Building Code, and shall have a total shear capacity equivalent to that of a wall one and one-half times the story height that is sheathed with a material that has an allowable shear value of one hundred fifty pounds per foot.

"Unreinforced masonry bearing walls" means masonry walls having all of the following characteristics:

1. Provide the vertical support for a floor or roof.
2. The total superimposed load is over one hundred pounds per linear foot.
3. The area of reinforcing steel is less than twenty-five percent of the minimum steel ratios required by the Uniform Building Code for reinforced masonry.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

1. 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.
2. Existing Unreinforced Masonry.
3. 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 and anchored to supporting elements; design of anchorage shall comply with requirements for anchorage of masonry veneer of Section 15.05.070(G).
4. Lay-up of 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 twenty-four 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 bonded 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 city building official.
5. Mortar A. Tests. The quality of mortar in unreinforced masonry walls shall be determined by performing inplace shear tests in accordance with Uniform Building Code Standard (21-6). Alternate methods of testing to establish compliance with the minimum requirement of Section 15.05.040(E) may be approved by the city building official.
6. 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 architect or engineer. An accurate record of such tests and their location in the building shall be recorded and these results shall be submitted to the city building official for approval as part of the structural analysis.
7. 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 one thousand five hundred square feet of wall area, whichever results in the greater number of tests.
8. Minimum Quality Mortar.
9. 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 /Ab)- P D+L / A w ...........(A1-1) where V to = Mortar shear test value, in psi. V test = Shear stress at incipient cracking for each inplace test per Standard No. 21.6. P D+L = Actual dead+live load in place at the time of testing, in pounds. A w = Area of the wall supporting P D+L at each in-place shear test.
10. Individual unreinforced masonry wall with V to less than thirty psi shall be pointed prior to retesting.
11. The mortar shear strength, V t is the value in psi representing a minimum of eighty percent of all the mortar shear test values, V to .
12. Unreinforced masonry with mortar shear strength, V t less than thirty psi shall be removed or pointed and retested.
13. Pointing. All deteriorated mortar joints in unreinforced masonry walls shall be pointed according to Standard No. 21-8. Nothing shall prevent pointing with mortar of all masonry walls joints before the tests are made, except as required in Section A107.1.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

1. Pointing. Special inspection shall be provided during preparation and mortar pointing. Exception: Incidental pointing may be performed without special inspection, at the discretion of the building official, and has been approved by the architect or engineer.
2. Existing Floor or Roof Level Wall Anchors.
3. Floor Level Tension Anchors Embedded in Brick. If existing rod anchors embedded in brick 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 or under the supervision of the architect or engineer. 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 five 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 three hundred 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 joist orientation. Ends of existing anchors shall be secured into the wood framing by a positive mechanical attachment.
4. Floor or Roof Level Anchors Embedded in Concrete. Existing rod anchors at floor or roof levels that are embedded in existing concrete or gunite applied to the opposite side of the wall need not be tested provided such embedment is verified by observation and report by an approved testing agency or the architect or engineer for at least one anchor, and all anchors observed, in each wall at each level for which such the anchors are to be utilized as all or part of the required wall anchorage system. Other evidence of such embedment may be approved by the city building official.
5. Testing of Bolts. One-fourth of new embedded bolts in unreinforced masonry walls shall be tested by a testing laboratory or architect or engineer using the procedure of U.B.C. Standard No 21-7 and 2001 California Standards Appendix Chapter 1. Exception: Special inspection in accordance with the building code or continuous observation by the architect or engineer may be provided during installation in lieu of testing.
6. Required Reports. The architect or engineer or testing agency shall submit a signed report to the city building official for each test, observation or inspection required by this section and Section 15.05.070(G). The report shall state the test, observation, or inspection performed, the date, the results of each individual test, observation or inspection, (including those that fail to satisfy the intent of this chapter) and whether to the best of the knowledge of the preparer of the report, the results indicate compliance with this chapter.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

1. Tension Anchors. Allowable values for tension anchors are given in Table A-1-E. A one-third increase is not allowed for values listed in this table.
2. Other Materials. Allowable values not specified in this chapter shall be as specified elsewhere in the 2001 California Building Code.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

1. Lateral Force on Elements of 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:

W p shall be as defined in Section 2332. The value of C p need not exceed the values set forth in Table No. 1C. 2. Height to Thickness Limitations. Unreinforced masonry wall height to thickness ratios shall not exceed ratios set forth in Table No. A-1-B. If a wall height to thickness ratio exceeds the specified limits, the wall shall be laterally supported by bracing members complying with Section 113.5.2 or with Section A113.5.3. Bracing systems shall be designed in accordance with Section 15.05.070(A). The wall thickness may include the thickness of plaster, stucco or concrete that is determined by the architect or engineer to be bonded to the full height of the wall between wall anchors. 3. 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, 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.
3. Wall Anchorage.
4. Anchor Locations. Unreinforced masonry walls shall be anchored at roof and floor levels in order to resist the forces specified in this section.
5. Tension Anchor Requirements. Tension anchors shall have a maximum spacing of six feet or six times the wall thickness, whichever is less, and shall comply with the requirements set forth in Table A-1-E. Tension anchors used to resist required forces may be assumed to develop the allowable values listed in Table No. A-1-E. Tension anchors shall be secured to the rafters or joists to transfer the required forces into the roof or floor sheathing.
6. New Tension Anchors. New tension anchors installed to meet the requirements of this section shall be combination tension and shear bolts, and shall be secured to the roof or floor framing to develop tension and shear forces into the diaphragm.
7. Minimum Wall Anchorage Forces. New or existing tension anchors shall anchor masonry walls to each floor or roof with a capacity to resist a minimum tension force determined in accordance with Chapter 16 of the Building Code or two hundred pounds per linear foot whichever is greater, acting normal to the wall at the level of the floor or roof. In addition, new combination tension and shear bolts shall be connected to the framing to resist a shear force of two hundred pounds per foot acting parallel to the wall at the level of the floor or roof.

Exception: Where the roof or floor sheathing consists only of one inch nominal thickness single board sheathing, new combination tension and shear bolts may be connected to the framing to resist a shear force of one hundred pounds per foot acting parallel to the wall.

The city building official may approve an analysis by the architect or engineer that demonstrates that the required shear capacity is less than required by this section. 5. Anchors at Corners. New combination tension and shear bolts at the roof and floor levels, if required by this section, shall be provided within two feet horizontally from the inside of the corners of the walls. 5. Parapets. Parapets and exterior wall appendages not capable of resisting the forces specified in this section 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 level of tension anchors shall not exceed the height to thickness ratio shown in Table A-1-F. If the required parapet height exceeds this maximum height, a bracing system designed for the force determined in accordance with Chapter 16 of the Building Code shall be installed to support the parapet. Parapet corrective work shall be performed in conjunction with the installation of tension roof anchors.

The minimum height of a parapet above the wall anchor shall be twelve 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. 6. Mortar Joints. All deteriorated mortar joints in unreinforced masonry walls shall be pointed according to U.B.C. Standard 21-8. 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 for pointing shall be inspected by the architect or engineer or their representative. 7. Masonry Veneer.

1. Veneer shall be anchored to the structures of the building with approved anchor ties conforming to the required design capacity specified in the Building Code and placed at a maximum spacing of twenty-four inches with a maximum supported area of two square feet.

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

Existing masonry veneer anchors ties shall be corrugated galvanized iron strips not less than one inch in width, eight inches in length and one-sixteenth 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 seventeen inches on center horizontally. As an alternate, such ties may be laid in every fourth course vertically at a spacing not to exceed nine inches on center horizontally.

Exception II: Masonry veneer, no portion of which six feet is above grade need not be anchored. 2. The location and condition of existing veneer anchor ties shall be verified as follows:

1. The architect or engineer shall determine the location and spacing of the ties.
2. The veneer shall be removed from not less than four locations designated by the architect or engineer for the architect or engineer's evaluation.
3. The architect or engineer shall report to the city building official the veneer anchor tie locations and spacings, their evaluation of the condition and effectiveness of the veneer anchor ties, and their recommendations whether or not the existing veneer anchor ties need to be supplemented with new veneer anchor ties.
4. Unreinforced masonry walls which carry no loads other than their own weight may be considered as veneer if they are adequately anchored to new supporting elements.

(Ord. 508 § 1 (part), 2003: Ord. 463 § 1 (part), 1995)

For time limits and technical specifications see Table Nos. 1-A, A-1-E, A-1-C and A-1-B; Standard Nos. 24-7 and 24-9.

Table No. 1-A Time Limits for Proceedings Following December 31, 1998 Deadline

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 one hundred or more.

Table No. A-1-E Allowable Values for Tension Anchors

Footnotes for Table A-1-E

1. A one-third increase in allowable stresses is not allowed, except as noted.
2. Values and limitations are for nailed plywood. Higher values may be used for other fastening systems such as wood screws or staples when approved by the building official.
3. In addition to existing sheathing value.
4. Bolts to be one-half inch (12.7 mm) minimum in diameter.
5. Drilling for bolts and dowels shall be done with an electric rotary drill. Impact tools shall not be used for drilling holes or tightening anchors and shear bolt nuts.
6. Other bolt sizes, values and installation methods may be used provided a testing program is conducted in accordance with U.B.C. Standard 21-7. Bolt spacing shall not exceed six feet (1830 mm) on center and shall not be less than twelve inches (305 mm) on center.
7. Embedded bolts to be tested as specified in Section A107.
8. Stresses given may be increased for combinations of loads as specified in the building code.

Table No. A-1-C****Horizontal Force Factor "C p " for Parts or Portions of Buildings or Other Structures

Table No. A-1-B Allowable Value of Height-Thickness Ratio or Unreinforced Masonry Walls with Minimum Quality Mortar

(Ord. 508 § 1 (part), 2003)