Los Angeles Municipal Code § 91.9401 Purpose

(Division 94 Added by Ord. No. 171,258, Eff. 8/30/96.)

Section

• 91.9401 Purpose.

• 91.9402 Scope.

• 91.9403 Definitions.

• 91.9404 General Requirements.

• 91.9405 Pre-design Investigation.

• 91.9406 Analysis and Design.

• 91.9407 Historical Buildings.

• 91.9408 Quality Control.

• 91.9409 Information Required on Plans.

(Amended by Ord. No. 172,592, Eff. 6/28/99, Oper. 7/1/99.)

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 existing hillside buildings constructed on or into slopes in excess of one unit vertical in three units horizontal (33.3% slope). Such buildings have been recognized as life hazardous as a result of partial or complete collapse that occurred during the Northridge Earthquake.

The provisions of this division are minimum standards for structural systems established primarily to reduce the risk of loss of life or injury resulting from earthquakes and will not necessarily prevent loss of life or injury or prevent earthquake damage to an existing building which complies with these standards.

This division provides voluntary retrofit standards under which buildings shall be permitted to be structurally analyzed and retrofitted. When fully followed, these standards will strengthen the portion of the structure that is most vulnerable to earthquake damage.

(Added by Ord. No. 171,258, Eff. 8/30/96.)

The provisions of this division may be applied to all existing hillside buildings designed under building codes effective prior to June 19, 1995. If only a portion of the building is supported on or into the slope, these regulations may be applied to the entire building.

Seismic retrofit work as described in this division may be applied to the portion of the structure defined as the base-level-diaphragm and below. Non-habitable accessory buildings, decks not supporting the main building, and existing conditions above the base-level-diaphragm are exempt from these regulations.

Seismic strengthening constructed prior to the effective date of the ordinance may be evaluated in accordance with the provisions of this division.

(Amended by Ord. No. 182,850, Eff. 1/3/14.)

For the purpose of this division, in addition to the applicable definitions, symbols and notations in this Code, certain additional terms are defined as follows:

BASE (BASE LEVEL) is the level at which the earthquake motions are considered to be imparted to the structure or the level at which the structure as a dynamic vibrator is supported.

BASE-LEVEL-DIAPHRAGM is the floor at, or closest to, the top of the highest level of the foundation.

DIAPHRAGM ANCHORS are assemblies that connect a diaphragm to the adjacent foundation at the uphill diaphragm edge.

DIAPHRAGM BACKSPAN is the horizontal cantilevered distance parallel to the direction of the lateral force, between the outermost vertical lateral force resisting elements and the edge of the diaphragm.

DOWNHILL-DIRECTION. The descending direction of the slope approximately perpendicular to the slope approximately perpendicular to the slope contours. (Amended by Ord. No. 186,488, Eff. 12/27/19.)

FOUNDATION is the concrete or masonry which supports a building, including footings, stem walls, retaining walls, and grade beams.

FOUNDATION EXTENDING IN THE DOWNHILL-DIRECTION. A foundation running downhill and approximately perpendicular to the uphill foundation. (Amended by Ord. No. 186,488, Eff. 12/27/19.)

FOUNDATION, UPHILL is a foundation parallel and closest to the uphill diaphragm edge, as defined herein.

HILLSIDE BUILDING. Any building or portion thereof constructed on or into a slope steeper than one-unit vertical in three-units horizontal (33.3% slope). If only a portion of the building is supported on or into the slope, these regulations apply to the entire building. (Amended by Ord. No. 186,488, Eff. 12/27/19.)

PRIMARY ANCHORS are diaphragm anchors designed for and providing direct connection as described in LAMC Subsections 91.9406.2 and 91.9406.3 between the diaphragm and the uphill foundation. (Amended by Ord. No. 185,587, Eff. 7/16/18.)

RETROFIT is an improvement of the lateral force resisting system of the structure by an alteration of existing or addition of new structural elements.

SECONDARY ANCHORS are diaphragm anchors designed for and providing a redundant diaphragm to foundation connection, as described in LAMC Subsection 91.9406.4. (Amended by Ord. No. 185,587, Eff. 7/16/18.)

UPHILL DIAPHRAGM EDGE is the edge of the diaphragm adjacent to or closest to the highest ground level at the perimeter of the diaphragm.

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

Except as modified herein, the analysis and design of the work within the scope of this division shall be in accordance with Division 16, Article 1, Chapter IX of the LAMC.

(Added by Ord. No. 171,258, Eff. 8/30/96.)

The engineer or architect shall prepare a pre-design field investigation report in accordance with Department guidelines and shall file the report when the plans are filed for permit. The plans shall include a description of the existing lateral force resisting system at and below the base.

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

Qualified Historical Buildings shall be allowed to use alternate building regulations or deviations from this division in order to preserve their original or restored architectural elements and features. See LAMC Section 91.8119 for these standards.