Los Angeles County Municipal Code Ch. 95 Earthquake Hazard Reduction for Existing Concrete Tilt-Up Buildings

Title 26 of the Los Angeles County Code is amended by adding Chapter 95, entitled "EARTHQUAKE HAZARD REDUCTION FOR EXISTING CONCRETE TILT-UP BUILDINGS," to read as follows:

SECTION 9501 - PURPOSE

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 fire protection systems to be altered.

(Ord. 2013-0048 § 80, 2013; Ord. 99-0040 § 74 (part), 1999.)

SECTION 9502 - SCOPE

The provisions of this Chapter shall apply to all tilt-up concrete wall buildings with flexible diaphragms constructed, under construction, or for which a building permit was issued prior to April 13, 1975.

(Ord. 2016-0053 § 86, 2016; Ord. 2007-0108 § 30 (part), 2007; Ord. 99-0040 § 74 (part), 1999.)

SECTION 9503 - DEFINITIONS

For purposes of this Chapter, the applicable definitions contained in 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 Chapter 2.

FLEXIBLE DIAPHRAGMS is defined as roofs and floors such as those sheathed with plywood, wood decking (1-by or 2-by) or metal decks without concrete topping slabs.

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. 2016-0053 § 87, 2016; Ord. 2013-0048 § 81, 2013; Ord. 2007-0108 § 30 (part), 2007; Ord. 2002-0076 § 146, 2002; Ord. 99-0040 § 74 (part), 1999.)

SECTION 9504 - ADMINISTRATION

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.)

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.)

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.)

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.)

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.)

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.)

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.)

SECTION 9505 - GENERAL REQUIREMENTS

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.)

Alterations and repairs required to meet the provisions of this Chapter shall comply with applicable structural requirements of this Code unless specifically modified in this Chapter.

(Ord. 2016-0053 § 88, 2016.)

The plans shall accurately reflect the results of the engineered investigation and design and shall show all pertinent dimensions and sizes for plan review and construction. The following shall be provided:

Floor plans and roof plans shall show existing framing construction, diaphragm construction, proposed wall anchors, cross- ties and collectors. Existing nailing, anchors, cross-ties and collectors shall also be shown on the plans if they are considered part of the lateral force-resisting systems.

At elevations where there are alterations or damage, details shall show roof and floor heights, dimensions of openings, locations and extent of existing alterations or damage and proposed repairs.

Typical wall panel details and sections with panel thickness, height, pilasters and location of anchors shall be provided.

Details shall include existing and new anchors and the method of developing anchor forces into the diaphragm framing, existing and/or new cross-ties, and existing and/or new or improved support of roof and floor girders at pilasters or walls.

The basis for design and the applicable Building Code used for the design shall be stated on the plans.

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. 2016-0053 § 88, 2016.)

Structural observation, in accordance with Section 1704.6, shall be required for all structures in which seismic retrofit is being performed in accordance with this Chapter. Structural observation shall include visual observation of work for conformance to the approved construction documents and confirmation of existing conditions assumed during design.

Structural testing and inspection for new construction materials shall be in accordance with this Code, except as modified by this Chapter.

(Ord. 2016-0053 § 88, 2016.)

SECTION 9506 - ANALYSIS AND DESIGN

Concrete and masonry 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 75 percent of the horizontal forces specified in Section 1613 of this Code.

(Ord. 2016-0053 § 89, 2016; Ord. 2007-0108 § 30 (part), 2007; Ord. 99-0040 § 74 (part), 1999.)

The steel elements of the wall anchorage system shall be designed in accordance with this Code without the use of the 1.33 short duration allowable stress increase when using allowable stress design.

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 (including dead 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 only allowed with special inspection and approved testing for seismic loading.

Attaching the edge of plywood sheathing to steel ledgers does not comply with the positive anchoring requirements of this Chapter. Attaching the edge of steel decks to steel ledgers is not considered as providing the positive anchorage of this Chapter unless testing and/or analysis is performed to establish shear values for the attachment perpendicular to the edge of the deck. Where steel decking is used as a wall anchor system, the existing connections shall be subject to field verification and the new connections shall be subject to special inspection.

(Ord. 2016-0053 § 89, 2016; Ord. 2013-0048 § 82, 2013; Ord. 2007-0108 § 30 (part), 2007; Ord. 99-0040 § 74 (part), 1999.)

Development of anchor loads into roof and floor diaphragms shall comply with Section 1613 of this Code, using horizontal forces that are 75 percent of those used for new construction.

Exception: If continuously tied girders are present, then the maximum allowable spacing between the continuity ties is the greater of the girder spacing or 24 feet (7314 mm). Added chords of diaphragms may be used to form subdiaphragms to transmit the anchorage forces to the main continuous cross-ties. The maximum shear used to determine the depth of the subdiaphragm shall not exceed 75 percent of the maximum diaphragm shear.

In wood diaphragms, anchorage shall not be accomplished by use of toenails or nails subject to withdrawal. Wood ledgers, top plates or framing shall not be used in cross-grain bending or cross-grain tension. The continuous ties required by Section 1613 of this Code 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.

(Ord. 2016-0053 § 89, 2016; Ord. 2010-0053 § 81, 2010; Ord. 99-0040 § 74 (part), 1999.)

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 edges of the two-way slab shall be considered fixed when there is continuity at pilasters and shall be considered pinned at roof and floor. 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 permitting 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 as required to resist the total anchorage force.

The minimum anchorage force at a floor or roof between the pilasters shall be that specified in Section 9506.1 of this Code.

(Ord. 2016-0053 § 89, 2016; Ord. 99-0040 § 74 (part), 1999.)

Symmetry of wall anchorage and continuity connectors about the minor axis of the framing member is required.

Exception: Eccentricity may be allowed when it can be shown that all components of forces are positively resisted. The resistance must be supported by calculations or tests.

(Ord. 2016-0053 § 89, 2016.)

New anchors used in combination on a single framing member shall be of compatible behavior and stiffness.

(Ord. 2016-0053 § 89, 2016.)

Existing interior reinforced concrete or reinforced masonry walls that extend to the floor above or to the roof diaphragm shall be anchored for out-of-plane forces per Sections 9506.1 and 9506.3. Walls extending through the roof diaphragm shall be anchored for out-of-plane forces on both sides, and continuity ties shall be spliced across or continuous through the interior wall to provide diaphragm continuity.

(Ord. 2016-0053 § 89, 2016.)

If collectors are not present at reentrant corners or interior shear walls, they shall be provided. Existing or new collectors shall be designed for the capacity required to develop into the diaphragm a force equal to the lesser of the rocking or shear capacity of the reentrant wall or the tributary shear based on 75 percent of the horizontal forces specified in Chapter 16 of this Code. The capacity of the collector need not exceed the capacity of the diaphragm to deliver loads to the collector. A connection shall be provided from the collector to the reentrant wall to transfer the full collector force (load). If a truss or beam other than a rafter or purlin is supported by the reentrant wall or by a column integral with the reentrant wall, then an independent secondary column is required to support the roof or floor members whenever rocking or shear capacity of the reentrant wall is less than the tributary shear.

(Ord. 2016-0053 § 89, 2016.)

Existing mezzanines relying on reinforced concrete or reinforced masonry 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.

(Ord. 2016-0053 § 89, 2016.)

SECTION 9507 - MATERIALS OF CONSTRUCTION

All materials permitted by this Code, including their appropriate strength or allowable stresses, may be used to meet the requirements of this Chapter.

(Ord. 2016-0053 § 90, 2016; Ord. 99-0040 § 74 (part), 1999.)

TABLE 95-A

TIME LIMITS FOR COMPLIANCE WITH EARTHQUAKE HAZARD REDUCTION COMPLIANCE ORDER1, 2

SUBMIT PLANS WITHIN OBTAIN PERMIT WITHIN COMMENCE COMPLETE ALTERATION ALTERATION

OR DEMOLITION OR DEMOLITION WITHIN WITHIN

12 months 18 months 24 months 36 months

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. 2013-0048 § 84, 2013; Ord. 2002-0076 § 154, 2002; Ord. 99-0040 § 74 (part), 1999.)