SEC. 91.9403. DEFINITIONS.
Los Angeles Building Code — LAMC Chapter IX · 2026-08 edition · updated 2026-09-09 · Los Angeles
(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.
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- Chapter IX
- Chapter IX — BUILDING REGULATIONS
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▸Division 94
- Division 95
- Division 96
- Division 5 — REGISTRATION
- Division 16A
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- Division 21
- Division 17
- Division 18
- Division C
- Division D