Loading...
ORD 157ORDINANCE NO. 157 AN ORDINANCE OF THE CITY COUNCIL OF THE CITY OF LA QUINTA, CALIFORNIA AMENDING TITLE 8 OF THE MUNICIPAL CODE BY ADDING A NEW CHAPTER 8.12 "EARTHQUAKE HAZARD REDUCTION IN EXISTING BUILDINGS". The City Council of the City of La Quinta does ordain as follows: SECTION 1. Title 8 of the Municipal Code is hereby amended by adding a new Chapter 8.12, the "Earthquake Hazard Reduction in Existing Buildings, attached hereto as Exhibit A. SECTION 2. EFFECTIVE DATE. This Ordinance shall be in full force and effective thirty (30) days after its adoption. SECTION 3. POSTING. The City Clerk shall, within 15 days after passage of this Ordinance, cause it to be posted in at least the three (3) public places designated by resolution of the City Council; shall certify to the adoption and posting of this Ordinance; and shall cause this Ordinance and it's certification, together with proof of posting, to be entered in the Book of Ordinances of this City. The foregoing ordinance was approved and adopted at a meeting of the City Council held on the 5th day of December, 1989, by the following vote: AYES: Council Members Bohnenberger, Bosworth, Rushworth, Sniff, Mayor Pena NOES: None ABSENT: None ABSTAIN: None JOHN J. *1PEJ,y City ofa, California ATTE AUNDRA JUHOLA, Ci&j Clerk City of La Quinta APPROVED AS TO FORM: DA N HONEYWELL, City Attorney City of La Quinta BJ/ORDDRFT.014 - 1 - STATE OF CALIFORNIA ) COUNTY OF RIVERSIDE ) ss. CITY OF LA QUINTA ) I, SAUNDRA L. JUHOLA, City Clerk of the City of La Quinta, California, do hereby certify the foregoing to be a full, true and correct copy of Ordinance No. 157 which was introduced on the 21st day of November, 1989 and was adopted at a regular meeting held on the 5th day of December, 1989, not being less than 5 days after date of introduction thereof. I further certify that the foregoing ordinance was posted in three (3) places with the City of La Quinta as specified in a reso tion of the City Council. zE34 SAUNDRA L. JUHOLA, ity Clerk City of La Quinta, California DECLARATION OF POSTING I, SAUNDRA L. JUHOLA, City Clerk of the City of La Quinta, Cali rnia, do hereby certify that the foregoing ordinance was pos a pursuant to City Council Resolution on December 7, 1989 SAUNDRA L. JUH City Clerk City of La Quinta, California CHAPTER 8.12 EARTHQUAKE HAZARD REDUCTION IN EXISTING BUILDINGS AUTHOR NOTE: Code Reference - 1985 Uniform Building Code is used because the model ordinance engineering standards are based upon the 1985 Uniform Building Codes. Only these types of buildings will be affected. SECTION 8.12.010 PURPOSE. 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 constructed prior to the adoption of earthquake design requirements. Such buildings have been widely recognized for sustaining life -hazardous damage, including partial or complete collapse during moderate to strong earthquakes. 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 alternation of existing electrical, plumbing, mechanical or fire safety systems unless they constitute a hazard to life or property. This Chapter provides systematic procedures and standards for identification and classification of unreinforced masonry bearing wall buildings based on their present use. Priorities, time periods and standards are also established under which these buildings are required to be structurally analyzed and anchored. Where the analysis finds deficiencies, this Chapter requires the building to be strengthened or demolished. Qualified Historical Buildings shall comply with the State Historical Building Code (SHBC) established under Part 8, Title 24, of the California Administrative Code. SECTION 8.12.020 SCOPE. The provisions of this Chapter shall apply to all buildings constructed which have unreinforced masonry bearing walls as defined herein. MR/ORDDRFT.024 -1- SECTION 8.12.030 DEFINITIONS. For purposes of this Chapter, the applicable definitions in Sections 2302 and 2312 of the Uniform Building Code shall apply: ESSENTIAL BUILDING: Any building housing a hospital or other medical facility having surgery or emergency treatment areas; fire or police stations; municipal government disaster operation and communication centers. HIGH RISK BUILDING: Any building, not classified an essential building, having an occupant load of 100 or more, as determined by Section 3302(a). EXCEPTION: A High Risk Building shall not include the following: 1. Any building having exterior walls braced with masonry crosswalls or wood frame crosswalls spaced less than 40 feet apart in each story. Crosswalls shall be full -story height with a minimum length of one -and -one-half times the story height. 2. Any building used for its intended purpose, as determined by the Building Official, for less than 20 hours per week. LOW RISK BUILDING: Any building, not classified as an essential building, having an occupant load of less than 20 occupants as determined by Section 3302(a). MEDIUM RISK BUILDING: Any building, not classified as a High Risk Building or an Essential Building, having an occupant load of 20 occupants or more as determined by Section 3302(a). UNREINFORCED MASONRY BEARING WALL: A masonry wall having all of 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 is less than 50 percent of that required by Section 2407(h). (1) All Section number references in the model ordinance that are not in the 88 series, e.g., Section 2302, Section 2312, Section 3302(a), and so forth, indicate passages in the Uniform Building Code, 1985 edition. MR/ORDDRFT.024 -2- SECTION 8.12.040 RATING CLASSIFICATIONS The rating classifications shown in Table No. 8.12-A are hereby established and each building within the scope of this Chapter shall be placed in one such rating classification by the Building Official. The total occupant load of the entire building as determined by Section 3302(a) shall be used to determine the rating classification. EXEMPTION: For the purpose of this Chapter, portions of buildings constructed to act independently when resisting seismic forces may be placed in separate rating classifications. SECTION 8.12.050 GENERAL REQUIREMENTS The owner of each building within the scope of this Chapter shall cause a structural analysis of the building to be made by a civil or structural engineer or architect 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 cause the building to be demolished. The owner of a building within'the scope of this Chapter shall comply with the requirements set forth above by submitting to the Building Official for review within the stated time limits: (a) Within 270 days after the service of the order, a structural analysis, which is subject to approval by the Building Official, and which shall demonstrate that the building meets the minimum requirements of this Chapter; or (b) Within 270 days after the service of the order, the structural analysis and plans for the proposed structural alterations of the building necessary to comply with the minimum requirements of this Chapter; or (c) Within 120 days after service of the order, plans for the installation of wall anchors in accordance with the requirements specified in Section 8807(c); or (d) Within 270 days after the service of the order, plans for the demolition of the building. MR/ORDDRFT.024 -3- 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. 8.12-B. These time limits shall begin to run from the date the order is served in accordance with Section 8.12.060(a) and (b). Owners electing to comply with Subsection (c) of this Section are also required to comply with Subsections (b) or (d) of this Section provided, however, that the 270-day period provided for in such Subsections (b) and (d) and the time limits for obtaining a building permit, commencing construction and completing construction for complete structural alterations or building demolition set forth in Table No. 8.12-B shall be extended in accordance with Table No. 8.12-C. Each such extended time limit, except the time limit for commencing construction shall begin to run from the date the order is served in accordance with Section 8.12.060(b). The time limit for commencing construction shall commence from the date the building permit is issued. SECTION 8.12.060 ADMINISTRATION. (a) Service of Order. The Building Official shall issue an order, as provided in Section 8.12.060(b), to the owner of each building within the scope of this Chapter in accordance with the minimum time periods for service of such orders set forth in Table No. 8.12-C. The minimum time period for the service of such orders shall be measured from the effective date of Chapter 8.12. Upon receipt of a written request from the owner, the Building Official shall order a building to comply prior to the normal service date for such building set forth in this Section. (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 as shown on the last equalized assessment, and upon the person, if any, in apparent charge or control of the building. 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 seismic standards of this Chapter. The order shall specify the rating classification of the building and shall be accompanied by a copy of Section 8.12.050 which sets forth the owner's alternatives and time limits for compliance. MR/ORDDRFT.024 -4- (c) charge or of Appeals that the Such appeal Chapter. within 60 described be decided date that in writing clearly and Appeal Form Order. The owner or person in control of the building may appeal to the Board the Building Official's initial determination building is within the scope of this Chapter. shall be filed within the scope of this Such appeal shall be filed with the Board days from the service date of the order in Section 8.12.060(b). Any such appeal shall by the Board no later than 60 days after the the appeal is filed. Such appeal shall be made and the grounds thereof shall be stated concisely. Appeals or requests for slight modifications from any other determinations, orders or actions by the Building Official pursuant to this Chapter, shall be made in accordance with the normal appeal procedures established in 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 8.12 EARTHQUAKE HAZARD REDUCTION IN EXISTING 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 Chapter 8.12. If the building is found not to 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 Chapter 8.12 - Earthquake Hazard Reduction in Existing Buildings. (e) Enforcement. If the owner or other person in charge or control of the subject building 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 8.12.050, the Building Official shall order the entire building vacated and 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 Appeals Board, the Building Official may order demolition of the building in accordance with the Abatement of Dangerous Buildings provisions of the Uniform Code for the Abatement of Dangerous Buildings. MR/ORDDRFT.024 -5- SECTION 8.12.070 ANALYSIS AND DESIGN. (a) General. Every structure within the scope of this Division 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 (8.12-1) The value of IKCS need not exceed the values set forth in Table 8.12-D based on the applicable rating classification of the building. (b) Lateral Forces on Elements of Structures. Parts or portions of structures shall be analyzed and designed for lateral loads in accordance with Subsections 8.12.070(a) and 2312(e) of the Uniform Building Code, but not less than the value from the following equation: Fp = ZICp SWp (8.12-2) For the provisions of this Subsection, the product of IS need not exceed the values as set forth in Table No. 8.12-F. EXCEPTION: Unreinforced masonry walls in buildings not having a rating classification of I may be analyzed in accordance with Section 8.12.080. The value of Cp need not exceed the values set forth in Table 8.12-F. (c) 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 Table No. 8.12-F of this Code and the equation Fp = ZICpSWp as modified by Table No. 8.12-E. Minimum anchorage of masonry walls to each floor or roof shall resist a minimum force of 200 pounds per linear foot acting normal to the wall at the level of the floor or roof. (d) Level of Required Repair. Alterations and repairs required to meet the provisions of this Chapter shall comply with all other applicable requirements of the Uniform Building Code unless otherwise specifically provided for in this Chapter. (e) Required Analysis. MR/ORDDRFT.024 -6- 1. General. Except as modified herein, the analysis and design relating to the structural alteration of existing structures within the scope of this Chapter shall be in accordance with the analysis specified in Chapter 23. 2. Continuous Stress Path. A complete, continuous stress path from every part or portion of the structure to the ground shall be provided for the required horizontal forces. 3. Positive Connections. All parts, portions or elements of the structure shall be interconnected by positive means. (f) Analysis Procedure. 1. General. Stresses in materials and existing construction utilized to transfer seismic forces from the ground to parts or portions of the structure shall conform' to those permitted by the Uniform Building Code and those materials and types of construction specified in Section 8.12.080. 2. Connections. Materials and connectors used for interconnection of parts and portions of the structure shall conform to the Uniform Building Code. Nails may be used as part of an approved connector. 3. Unreinforced Masonry Walls. Except as modified herein, unreinforced masonry walls shall be analyzed as specified in Section 2406, 2407 and 2408 to withstand all vertical loads as specified in Chapter 23 of the Uniform Building Code in addition to the seismic forces required by this Chapter. The 50 percent increase in the seismic force factor for shear walls as specified in Section 2407(h)4F of the Uniform Building Code may be omitted in the computation of seismic loads to existing shear walls. 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 a Rating Classification I pursuant to Table No. 8.12-A may be analyzed in accordance with Section 8.12.080. MR/ORDDRFT.024 -7- 2. An unreinforced masonry wall which carries no design loads other than its own weight may be considered as veneer if it is adequately anchored to new supporting elements. (g) Combination of Vertical and Seismic Forces. 1. New Materials. All new materials introduced into the structure to meet the requirements of this section which are subjected to combined vertical and horizontal forces sha:_ comply with Section 2303(f). 2. Existing Materials. When stresses in existing lateral force resisting elements are due to a combination of dead loads plus live loads plus seismic loads, the allowable working stress specified in the Uniform Building Code may be increased 100 percent. However, no increase will be permitted in the stresses allowed in Section 8.12.080, and the stresses in members due only to seismic and dead loads shall not exceed the values permitted by Section 2303(d) of the Uniform Building Code. 3. Allowable Reduction of Bending Stress by Vertical Load. In calculating tensile fiber stress due to seismic forces required by this chapter, the maximum tensile fiber stress may be reduced by the full direct stress due to vertical dead loads. SECTION 8.12.080 MATERIALS OF CONSTRUCTION (a) General. All materials permitted by the Uniform Building Code including their appropriate allowable stresses and those existing configurations of materials specified herein may be utilized to meet the requirements of this Chapter. (b) Existing Materials. 1. Unreinforced Masonry Walls. Unreinforced masonry walls analyzed in accordance with this Section may provide vertical support for roof and floor construction and resistance to lateral loads. The facing and backing of such walls shall be bonded so that not less than four percent of the exposed face area is composed of solid headers extended not less than four inches into the backing. The distance between adjacent full-length headers shall not exceed 24 inches vertically or horizontally. where the backing consists of two or more wythes, the header shall MR/ORDDRFT.024 extend not less than four inches into the most distant wythe, or the backing wythes shall be bonded together with separate headers whose area and spacing conform to the foregoing. Tension stresses due to seismic forces normal to the wall may be neglected if the walls do not exceed the height to thickness ratio in Table No. 8.12-G and the in -plane shear stresses due to seismic loads as set forth in Table No. 8.12-J. If the wall height -thickness ratio exceeds the specified limits, the wall may be supported by vertical bracing members designed in accordance with Section 8.12.070. The deflection of such bracing member at design loads shall not exceed one -tenth of the wall thickness. EXCEPTION: The wall may be supported by flexible vertical bracing members designed in accordance with Section 8.12.070(b) if the deflection at design loads is not less than one -quarter nor more that one-third of the wall thickness. 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. The wall height may be measured vertically to bracing elements other than a floor or roof. Spacing of the 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. Existing Roof, Floors, Walls, Footings, and Wood Framing. Existing materials including wood shear walls utilized in the described configuration may be used as part of the lateral load resisting system, provided that the stresses in these materials do not exceed the values shown in Table No. 8.12-H. (c) Strengthening of Existing Materials. New materials including wood shear walls may be utilized to strengthen portions of the existing seismic resisting system in the described configurations provided that the stresses do not exceed the values shown in Table No. 8.12-I. MR/ORDDRFT.024 -9- (d) Alternate Materials. Alternate materials, designs and methods of construction may be approved by the building official in accordance with the provisions of the Uniform Building Code. (e) 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. Alternate methods of testing may be approved by the Building Official. The quality of mortar in all masonry walls shall be determined by performing in -place shear tests or by testing eight inch diameter cores. Alternative methods of testing may be approved by the Building Official. Nothing shall prevent 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 that masonry cements shall not be used. All preparation and mortar pointing shall be done under the continuous inspection of a Registered Deputy Building Inspector. At the conclusion of the inspection, the inspector shall submit a written report to the licensed engineer or architect responsible for the seismic analysis of the building, setting forth the result 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 performed in accordance with the requirements specified in this subsection by a testing agency approved by the Building Official. An accurate record shall be kept of all such tests and of their locations in the building, and these results shall be submitted to the Building Official for approval as part of the structural analysis. 2. Number and Location of Tests. The minimum number of tests shall be two per wall or line of wall elements resisting a common force, or 1 per 1500 square feet of wall surface, with a minimum of eight tests in any case. The exact test or core location shall be determined at the building site by the licensed engineer or architect responsible for the seismic analysis of the subject building. MR/ORDDRFT.024 -10- 3. In -Place 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 wythe. The opposite head joint of the brick to be tested shall be removed and cleaned prior to testing. The minimum quality mortar in 80 percent of the shear tests shall not be less than the total of 30 psi plus the axial stress shall be based on the gross area of both bed joints and shall be that at which movement of the brick is first observed. 4. Core Tests. A minimum number of mortar test specimens equal to the number of required cores shall be prepared from the cores and tested as specified herein. The mortar joint of the outer wythe of the masonry core shall be tested in shear by placing the circular core section in a compression testing machine with the mortar bed joint rotated 15 degrees from the axis of the applied load. The mortar joint tested in shear shall have an average ultimate stress of 20 psi based on the gross area. The average shall be obtained from the total number of cores made. If test specimens cannot be made from cores taken, then the shear value shall be reported as zero. (f ) Testing of Shear- Bolts. One-fourth of all new shear bolts and dowels embedded in unreinforced masonry walls shall be tested by a Special Inspector using a torque calibrated wrench to the following minimum torques: 1/2" diameter bolts or dowels = 40 foot-lbs. 5/8" diameter bolts or dowels = 50 foot-lbs. 3/4" diameter bolts or dowels = 60 foot-lbs. No bolts exceeding three-quarters inch shall be used. All nuts shall be installed over malleable iron or plate washers when bearing on wood and heavy cut washers when bearing on steel. (g) 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 Section 8.12.080(e) 3 and 4. Design stresses shall be related to test results obtained in accordance with Table No. 8.12-J. Intermediate values between 3 and 10 psi may be interpolated. MR/ORDDRFT.024 -11- 2. Design Compression and Tension Values. Compression stresses for unreinforced masonry having a minimum design shear value of 3 psi shall not exceed 100 psi. Design tension values for unreinforced masonry shall not be permitted. (h) Five percent of the existing rod anchors utilized as all or part of the required wall anchors shall be tested in pullout by an approved testing laboratory. The minimum number 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. 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 lbs. 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. The allowable resistance value of the existing anchors shall be 40 percent of the average of those tested anchors having the same wall thickness and joist orientation. (i) Qualification tests for devices used for wall anchorage shall be tested with the entire tension load carried on the enlarged head at the exterior face of the wall. Bond on the part of the device between the enlarged head and the interior wall face shall be eliminated for the qualification tests. The resistance value assigned the device shall be 20 percent of the average of the ultimate loads. SECTION 8.12.090 INFORMATION REQUIRED ON PLANS (a) General. In addition to the seismic analysis required elsewhere in this Chapter, the licensed engineer or architect responsible for the seismic analysis of the building shall determine and record the information required by this Section on the approved plans. (b) Construction Details. The following requirements with appropriate construction details shall be made part of the approved plans. 1. All unreinforced masonry walls shall be anchored at the roof level by tension bolts through the wall as specified in Table No. 8.12-I, or by approved equivalent at a maximum anchor spacing of six feet. MR/ORDDRFT.024 -12- All unreinforced masonry walls shall be anchored at all floors with tension bolts through the wall or by existing rod anchors at the maximum anchor spacing of six feet. All existing rod anchors shall be secured to the joists to develop the required forces. The Building Official may require testing to verify the adequacy of the embedded ends of existing rod anchors. Tests, when required, shall conform to Section 8.12.080(h). When access to the exterior face of the masonry wall is prevented by proximity of an existing building, wall anchors conforming to Items 5 and 6 in Table No. 8.12-I may be used. Alternative devices to be used in lieu of tension bolts for masonry wall anchorage shall be tested as specified in Section 8.12.080(i). 2. Diaphragm chord stresses of horizontal diaphragms shall be developed in existing materials or by addition of new materials. 3. Where trusses and beams other than rafters or joists are supported on masonry, ledgers or columns shall be installed to support vertical loads of the roof or floor members. 4. Parapets and exterior wall appendages not capable of resisting the forces specified in this chapter shall be removed, stabilized or braced to insure that the parapets and appendages remain in their original position. 5. 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 the continuous inspection of a special inspector certified to inspect masonry or concrete. At the conclusion of the project, the inspector shall submit a written report to the building official setting forth the portion of work inspected. 6. Repair details shall be prepared 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: MR/ORDDRFT.024 -13- 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 parapet corrections, if any, which were performed in accordance with the Uniform Building Code. 4. Accurately dimensioned floor plans and masonry wall elevations showing dimensioned openings, piers, wall thickness and heights. 5. The location of cracks or damaged portions of unreinforced masonry walls requiring repairs. 6. The type of interior wall surfaces and whether reinstalling or anchoring of ceiling plaster is necessary. 7. The general condition of the mortar joints and whether the joints need pointing. MR/ORDDRFT.024 -14- i