The purpose of this Chapter is to promote public safety and welfare by reducing the risk of death or injury which might otherwise result from earthquake damage to concrete tilt-up buildings constructed, under construction, or for which a building permit was issued prior to April 13, 1975. Such buildings have been widely recognized as having a potentially significant risk of sustaining life-hazardous damage, including partial or complete collapse during moderate to strong earthquakes, due to inadequate wall anchorage to the horizontal diaphragm.
This Chapter provides systematic procedures and standards for identification of such concrete tilt-up wall buildings, and time periods under which these buildings are required to be structurally analyzed and anchored. Where analysis finds deficiencies, this Chapter requires the building to be strengthened or demolished.
This Chapter sets forth minimum standards for structural seismic resistance to reduce the risk of loss of life and injury by the installation of wall anchors and connections to the horizontal diaphragms. 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 existing electrical, plumbing, mechanical or firesafety systems to be altered. (Ord. 99-0040 § 74 (part), 1999.)

The provisions of this Chapter shall apply to all buildings constructed, under construction, or for which a building permit was issued prior to April 13, 1975, and which on the effective date of this ordinance have concrete tilt-up bearing walls as defined herein. (Ord. 2007-0108 § 30 (part), 2007: Ord. 99-0040 § 74 (part), 1999.)

For purposes of this Chapter, the applicable definitions in Chapter 16 of this Code and the following definitions shall apply.

ESSENTIAL FACILITIES is defined as any building conforming to the definition of essential facilities as set forth in Section 1602.1 of this Code.

TILT-UP CONCRETE WALL is a form of precast concrete panel construction, where the panel is either cast at the construction site in a horizontal position, or offsite and, after curing, incorporated into the structure of the building, in a vertical position. (Ord. 2007-0108 § 30 (part), 2007; Ord. 2002-0076 § 146, 2002: Ord. 99-0040 § 74 (part), 1999.)

9504.1 Service of Order. The Department of Public Works shall attempt to identify those buildings within the scope of this Chapter and shall take reasonable measures to issue an Earthquake Hazard Reduction Compliance Order as provided in this Section. (Ord. 99-0040 § 74 (part), 1999.)

9504.2 Contents of Order. The Earthquake Hazard Reduction Compliance Order shall be in writing and shall be served either personally or by mail, postage prepaid, upon the owner as shown on the last equalized assessment, or by posting on the building. The order shall specify that the building appears to be within the scope of this Chapter and, therefore, is required to meet the minimum seismic standards of this Chapter. The order shall also specify the time limits for appeal of and compliance with the order. (Ord. 2002-0076 § 147, 2002: Ord. 99-0040 § 74 (part), 1999.)

9504.3 Appeal from Order. The owner may appeal the Building Official’s initial determination that the building is within the scope of this Chapter to the Building Board of Appeals established by Section 105. Such appeal shall be filed with the Board within 60 days from the service date of the order described in Section 9504.2. Any such appeal shall be heard by the Board no later than 90 days after the date that the appeal is filed. Such appeal shall be made in writing and the grounds thereof shall be stated clearly and concisely. All materials which the appellant wishes considered by the Building Board of Appeals shall be submitted to the Board 14 calendar days before the hearing.
Appeals and requests for modifications from any other determinations, orders or actions of the Department of Public Works pursuant to this Chapter shall be made in accordance with the normal appeal procedures established in Sections 104.2.7 and 105. (Ord. 2002-0076 § 148, 2002: Ord. 99-0040 § 74 (part), 1999.)

9504.4 Recordation. At or about the time that the Earthquake Hazard Reduction Compliance Order is served, the Department of Public Works shall file with the Office of the County Recorder a certificate stating that the subject building appears to be within the scope of Chapter 95. The certificate shall state that the owner thereof has been ordered to structurally analyze the building and, if necessary, to structurally alter or demolish the building as set forth in Chapter 95. The certificate shall also state that the owner has 60 days from the date of the order to appeal the determination that the subject building is within the scope of Chapter 95 and that if such an appeal is not submitted, the determination will be final and binding.
If the building is subsequently determined by the Department of Public Works not to be within the scope of this Chapter, or is demolished, or is modified so as to meet the requirements of this Chapter, the Department of Public Works 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 95. (Ord. 2002-0076 § 149, 2002; Ord. 99-0040 § 74 (part), 1999.)

9504.5 Enforcement. If the owner of the subject building fails to comply with any order issued by the Department of Public Works pursuant to this Chapter, the Department of Public Works may order the entire building vacated and maintained vacated until such compliance has been accomplished. If, within 90 days after the date the building has been ordered vacated, or within such additional time as may have been granted by the Building Board of Appeals, the owner or other person in charge or control of the subject building has still not complied with any order issued pursuant to this Chapter, the Department of Public Works may order demolition of the building in accordance with the provisions of Section 102 of this Code. (Ord. 2002-0076 § 150, 2002: Ord. 99-0040 § 74 (part), 1999.)

9504.6 Prosecution. In case the owner shall fail, neglect or refuse to comply with the directions in the Earthquake Hazard Reduction Compliance Order (if neither the owner nor any other person requests a hearing) or with any order of the Building Board of Appeals, the owner shall be guilty of a misdemeanor and the building official may cause such owner of the building or property to be prosecuted as a violator of this Code. (Ord. 2002-0076 § 151 (part), 2002.)

9504.7 Other Abatement Procedures. The provisions of this Chapter shall not in any manner limit or restrict the County or the District Attorney from enforcing County Ordinances or abating public nuisances in any other manner provided by law. (Ord. 2002-0076 § 151 (part), 2002.)

The owner of each building within the scope of this Chapter shall, upon service of an Earthquake Hazard Reduction Compliance Order, cause a structural analysis of the building to be made by a civil or structural engineer or architect licensed by the State of California to conduct structural analysis and shall submit such analysis to the Department of Public Works for review. The structural analysis shall state whether or not the building meets the requirements of this Chapter. If such a structural analysis indicates that the building does not meet the requirements of this Chapter, the owner shall either obtain a demolition permit and demolish the building or submit plans for structural alterations of the building so that it will comply with the provisions of this Chapter together with a structural analysis so indicating, and perform the work.
The owner shall submit the required structural analysis, obtain any necessary permits and commence and complete the required alteration or demolition within the time limits set forth in Table 95-A. These time limits shall run from the date the Earthquake Hazard Reduction Compliance Order is served.
Once an Earthquake Hazard Reduction Compliance Order has been served, buildings within the scope of this Chapter may not be structurally altered, remodeled or added to without first complying with the provisions of this Chapter unless the Building Official determines that the alteration is minor in nature. (Ord. 2002-0076 § 152, 2002: Ord. 99-0040 § 74 (part), 1999.)

9506.1 Wall Panel Anchorage. Concrete walls shall be anchored to all floors and roofs which provide lateral support for the wall. The anchorage shall provide a positive direct connection between the wall and floor or roof construction capable of resisting a horizontal force equal to 45 percent of the tributary wall weight for essential facilities, and 30 percent of the tributary wall weight for all other buildings, or a minimum force of 250 pounds per linear foot (3.65 kN/m) of wall, whichever is greater. The required anchorage shall be based on the tributary wall panel assuming simple supports at floors and roof. (Ord. 2007-0108 § 30 (part), 2007: Ord. 99-0040 § 74 (part), 1999.)

9506.2 Special Requirements for Wall Anchors and Continuity Ties. The steel elements of the wall anchorage systems and continuity ties shall be designed by the allowable stress design method using a load factor of 1.7. The one-third stress increase permitted by Section 1605.3.2 shall not be permitted for materials using allowable stress design methods.
The strength design specified in Section 1912, using a load factor of 2.0 in lieu of 1.4 for earthquake loading, shall be used for design of embedments in concrete.
Wall anchors shall be provided to resist out-of-plane forces, independent of existing shear anchors.

EXCEPTION: Existing cast-in-place shear anchors may be used as wall anchors if the tie element can be readily attached to the anchors and if the engineer or architect can establish tension values for the existing anchors through the use of approved as-built plans or testing, and thorough analysis showing that the bolts are capable of resisting the total shear load while being acted upon by the maximum tension force due to earthquake. Criteria for analysis and testing shall be determined by the Building Official.

Expansion anchors are not allowed without specific approval of the Building Official. Attaching the edge of steel decks or plywood sheathing to steel ledgers does not comply with the positive anchoring requirements of the Code. (Ord. 2007-0108 § 30 (part), 2007; Ord. 99-0040 § 74 (part), 1999.)

9506.3 Development of Anchor Loads into the Diaphragm. Development of anchor loads into roof and floor diaphragms shall comply with Section 9506.10 of this Code.

EXCEPTION: If continuously tied girders are present, then the maximum allowable spacing between the continuity ties is 36 feet (10 973 mm).

In wood diaphragms, anchorage shall not be accomplished by use of toenails or nails subject to withdrawal, nor shall wood ledgers, top plates, or framing be used in cross-grain bending or cross-grain tension. The continuous ties required by Section 9506.10 shall be in addition to the diaphragm sheathing.
Lengths of development of anchor loads in wood diaphragms shall be based on existing field nailing of the sheathing unless existing edge nailing is positively identified on the original construction plans or at the site.
At re-entrant corners, continuity collectors may be required for existing return walls not designed as shear walls, to develop into the diaphragm a force equal to the lesser of the rocking or shear capacity of the return wall, or the tributary shear, but not exceeding the capacity of the diaphragm. Shear anchors for the return wall shall be commensurate with the collector force. If a truss or beam other than rafters or purlins is supported by the return wall or by a column integral with the return wall, an independent secondary column is required to support the roof or floor members.
Seismic design of return walls and fins/canopies at entrances shall ensure deflection compatibility with the diaphragm by either seismically isolating the element or attaching the element and integrating its load into the diaphragm. (Ord. 2010-0053 § 81, 2010; Ord. 99-0040 § 74 (part), 1999.)

9506.4 Anchorage at Pilasters. Anchorage of pilasters shall be designed for the tributary wall anchoring load per Section 9506.1 of this Code, considering the wall as a two-way slab. The pilasters or the walls immediately adjacent to the pilasters shall be anchored directly to the roof framing such that the existing vertical anchor bolts at the top of the pilasters are by-passed without causing tension or shear failure at the top of the pilasters.

EXCEPTION: If existing vertical anchor bolts at the top of the pilasters are used for the anchorage, then additional exterior confinement shall be provided.

The minimum anchorage at a floor or roof between the pilasters shall be that specified in Section 9506.1 of this Code. (Ord. 99-0040 § 74 (part), 1999.)

9506.5 Evaluation of Existing Structural Conditions. If the structural analysis submitted pursuant to Section 9505 indicates that the building does not meet the requirements of this Chapter, the engineer or architect shall include in said analysis a report of any observed structural conditions, including, but not limited to, cracks, structural damage or alterations, that may have a substantial effect on the seismic integrity of the building and shall include provisions for the repair of these conditions in the plans submitted to the department for review and approval. (Ord. 99-0040 § 74 (part), 1999.)

9506.6 Miscellaneous. Existing mezzanines relying on the tilt-up walls for vertical and/or lateral support shall be anchored to the walls for the tributary mezzanine load. Walls depending on the mezzanine for lateral support shall be anchored per Sections 9506.1, 9506.2 and 9506.3.

EXCEPTION: Existing mezzanines that have independent lateral and vertical support need not be anchored to the walls.

Existing interior masonry or concrete walls, not designed as shear walls, which extend to the floor above or to the roof diaphragm shall also be anchored for out-of-plane forces per Sections 9506.1, 9506.2 and 9506.3 of this Code. In the in-plane direction, the walls shall be isolated or developed into the diaphragm to resist a lateral force equal to the lesser of the rocking or shear capacity of the wall, or the tributary shear, but in no event to exceed the diaphragm capacity. (Ord. 2002-0076 § 153, 2002: Ord. 99-0040 § 74 (part), 1999.)

9506.7 Symmetry. Symmetry of anchorage systems is required. Non-symmetrical anchorage systems may be allowed when it can be shown that all components of forces are positively resisted as determined by calculations or tests. (Ord. 99-0040 § 74 (part), 1999.)

9506.8 Minimum Roof Member Size. Wood members used to develop anchorage forces to the diaphragm shall not be less than 3-inch (76mm) nominal thickness when damaged members are replaced. All such members must be checked for earthquake loads as part of the wall anchorage system in addition to dead and live loads. For existing buildings, the member check shall be without the one-third stress increase per Section 1605.3.2. (Ord. 2007-0108 § 30 (part), 2007: Ord. 99-0040 § 74 (part), 1999.)

9506.9 Combination of Anchor Types. The maximum allowable combined load resisted by a combination of different types of anchors that exhibit different behavior or stiffness is not the sum of the allowable load for each anchor. The combined capacity of the new and existing connectors shall be taken as the allowable load of the stiffest anchor.

EXCEPTION: Existing anchors may be combined with new anchors for retrofit projects where existing anchors are undamaged and will resist loads equally with a new anchor of identical manufacture, type and installation. The combined allowable load shall be twice the allowable load of a single anchor.

(Ord. 99-0040 § 74 (part), 1999.)

9506.10 Diaphragms. Diaphragms supporting concrete walls shall have continuous ties or struts between diaphragm chords to distribute the anchorage forces specified in Section 12.11 of ASCE 7. The spacing of continuous ties shall not exceed 25 feet (7620 mm). Added chords of subdiaphragms may be used to form subdiaphragms to transmit the anchorage forces to the main continuous crossties. The maximum diaphragm shear used to determine the depth of the subdiaphragms shall not exceed 300 pounds per foot (4.38 kN/m). The maximum length-to-width ratio of the wood structural subdiaphragm shall be 2 ½:1. (Ord. 2010-0053 § 82, 2010.)

All materials permitted by this Code may be utilized to meet the requirements of this Chapter. (Ord. 99-0040 § 74 (part), 1999.)

9508.1 General. Plans submitted pursuant to the provisions of this Chapter shall be signed by the licensed civil or structural engineer or architect responsible for the seismic analysis of the building and shall comply with the requirements of this Code and this Section. (Ord. 99-0040 § 74 (part), 1999.)

9508.2 Plans and Specifications. Plans, engineering calculations, diagrams and other data shall be submitted in two or more sets with each application for a building permit. (Ord. 99-0040 § 74 (part), 1999.)

9508.3 Information on Plans and Specifications. Plans and specifications shall be drawn to scale upon substantial medium and shall be of sufficient clarity to indicate the location, nature and extent of the work proposed and show in detail that the proposed work will conform to the provisions of this Chapter and all relevant Codes, laws, ordinances, rules and regulations. (Ord. 99-0040 § 74 (part), 1999.)

9508.4 Existing Construction. The following information shall be made part of the approved plans:
1. The type and dimensions of existing walls and the size and spacing of existing floor and roof members.
2. The extent and type of existing wall anchorage of floors and roof members.
3. Accurately dimensioned plans and/or elevations of existing floors and concrete walls showing dimensioned openings, piers, wall thicknesses and heights.
4. The location and extent of any structural conditions as specified in Section 9506.5. (Ord. 99-0040 § 74 (part), 1999.)

¹ All dates are measured from the date the Earthquake Hazard Reduction Compliance Order is served pursuant to Section 9504.

² For any work required by this Chapter, the time limits shown herein shall supersede the time limits specified in Section 106.5.4.

(Ord. 2002-0076 § 154, 2002: Ord. 99-0040 § 74 (part), 1999.)