Los Angeles Municipal Code § 91.9603 Definitions

(Division 96 Added by Ord. No. 171,261, Eff. 8/30/96.)

Section

• 91.9601 Purpose.

• 91.9602 Scope.

• 91.9603 Definitions.

• 91.9604 Analysis and Design.

• 91.9605 Materials of Construction.

• 91.9606 Information Required on Plans.

(Added by Ord. No. 171,261, Eff. 8/30/96.)

The purpose of this division is to promote public safety and welfare by reducing the risk of death or injury that may result from the effects of earthquakes on reinforced concrete and masonry wall buildings with flexible diaphragms designed under the building codes in effect prior to January 1, 1995. These buildings are potentially hazardous and prone to significant damage, including possible collapse, in a moderate to major earthquake. These structures typically shelter large numbers of persons and property for retail, food markets, food distribution centers, warehousing, aerospace, industrial/manufacturing and general business and office use. Their continued use after an earthquake is also essential to the local economy and its post-earthquake recovery.

The provisions of this division are minimum standards for structural seismic resistance established primarily to reduce the risk of loss of life or injury on both subject and adjacent properties and will not necessarily prevent all earthquake damage to an existing building which complies with these standards. This division shall not require existing electrical, plumbing, mechanical or fire-safety systems to be altered unless they constitute a hazard to life or property.

This division provides voluntary retrofit standards for deficient wall anchorage systems on structures that are not subject to the mandatory provisions of Division 91, Article 1, Chapter IX of the LAMC. When fully followed, these standards will strengthen the portion of the structure that is most vulnerable to earthquake damage. (Amended by Ord. No. 185,587, Eff. 7/16/18.)

(Added by Ord. No. 171,261, Eff. 8/30/96.)

The voluntary provisions of this division shall apply to existing buildings of the following types:

1. Cast-in-place reinforced concrete or masonry wall buildings with flexible diaphragms designed under building codes in effect prior to January 1, 1995.

2. Tilt-up concrete wall buildings with flexible diaphragms designed under the building codes in effect prior to January 1, 1995, but after January 1, 1976.

All tilt-up concrete wall buildings designed under the Building Code in effect prior to January 1, 1976, are subject to the mandatory provisions of Division 91, Article 1, Chapter IX of the LAMC. All existing reinforced masonry or concrete buildings with flexible diaphragms, including tilt-up concrete wall buildings, designed under the Building Code in effect on or after January 1, 1995, shall be designed in conformance with Division 16, Article 1, Chapter IX of the LAMC. (Amended by Ord. No. 185,587, Eff. 7/16/18.)

(Amended by Ord. No. 185,587, Eff. 7/16/18.)

For the purposes of this division, the applicable definitions in CBC Sections 1602, 1613.2, 1902 and 2302; ASCE 7 Sections 1.2, 3.1, 4.1 and 11.2; and the following shall apply:

ANCHORAGE SYSTEM is the system of all structural elements and connections, which support the concrete or masonry wall in the lateral direction, including diaphragms and subdiaphragms, wall anchorage and continuity or cross tie connectors in subdiaphragms and main diaphragms.

COMMENCED CONSTRUCTION is construction pursuant to a valid building permit that has progressed to the point that one of the called inspections as required by the Department has been made and the work for which the inspection has been called has been judged by the Department to be substantial and has been approved by the Department.

EXISTING BUILDING is an erected building for which a legal building permit and a certificate of occupancy have been issued.

FLEXIBLE DIAPHRAGM is any diaphragm constructed of wood structural panel, diagonal or straight wood sheathing, metal decking without a structural concrete topping, or horizontal rod bracing.

HISTORICAL BUILDING is any building designated or currently in the process of being designated as a historical building by an appropriate federal, state or City jurisdiction.

REINFORCED CONCRETE WALL. A concrete wall that has 50% or more of the reinforcing steel required for reinforced concrete in Division 19, Article 1, Chapter IX of the LAMC.

REINFORCED MASONRY WALL. A masonry wall that has 50 percent or more of the reinforcing steel required by Section 2.3 or Section 3.3 of ACI 530-05/ASCE 5-05/TMS 402/602-16 (MSJC). (Amended by Ord. No. 186,488, Eff. 12/27/19.)

RETROFIT is strengthening or structurally improving the lateral force resisting system of an existing building by alteration of existing or addition of new structural elements.

TILT-UP CONCRETE WALL is a form of precast concrete panel construction either cast in the horizontal position at the site and after curing, lifted and moved into place in a vertical position, or cast off-site in a fabricator’s shop.

(Amended by Ord. No. 185,587, Eff. 7/16/18.)

All materials permitted by this Code, including their appropriate allowable stresses and those existing configurations of materials specified in Division 88, Article 1, Chapter IX of the LAMC, may be utilized to meet the requirements of this division.