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Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

Section A104 — SYMBOLS AND NOTATIONS

2025 California Existing Building Code (Title 24, Part 10) · 2025 edition · updated 2026-07-27 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

[BS] A104.1 Symbols and notations. For the purpose of this chapter, the following notations supplement the applicable symbols and notations in the building code.

a n = Diameter of core multiplied by its length or the area of the side of a square prism. A = Cross-sectional area of unreinforced masonry pier or wall, square inches (10 [-6] m [2] ). A b = Total area of the bed joints above and below the test specimen for each in-place shear test, square inches (10 [-6] m [2] ). A n = Area of net mortared or grouted section of a wall or wall pier. D = In-plane width dimension of pier, inches (10 [-3] m), or depth of diaphragm, feet (m).

DCR = Demand-capacity ratio specified in Section A111.4.2.

f ′ m = Lower bound masonry compressive strength. f sp = Splitting-tensile strength of masonry. F wx = Force applied to a wall at level x, pounds (N). H = Least clear height of opening on either side of a pier, inches (10 [-3] m).

h/t = Height-to-thickness ratio of URM wall. Height, h, is measured between wall anchorage levels and/or slab-on-grade.

L = Span of diaphragm between shear walls, or span between shear wall and open front, feet (m). L c = Length of crosswall, feet (m). L i = Effective diaphragm span for an open-front building specified in Section A111.8, feet (m). P = Applied force as determined by standard test method of ASTM C496 or ASTM E519, pounds (N).

P D = Superimposed dead load at the location under consideration, pounds (N). For determination of the rocking shear capacity, dead load at the top of the pier under consideration shall be used.

P D+L = Stress resulting from the dead plus actual live load in place at the time of testing, pounds per square inch (kPa). P test = Splitting tensile test load determined by standard test method ASTM C496, pounds (N). P w = Weight of wall, pounds (N). R = Response modification factor for Ordinary plain masonry shear walls in Bearing Wall System from Table 12.2-1 of ASCE 7, where R = 1.5.

S DS = Design spectral acceleration at short period, in g units. S D1 = Design spectral acceleration at 1-second period, in g units. v a = The shear strength of any URM pier, v m A/1.5 pounds (N). v c = Unit shear strength for a crosswall sheathed with any of the materials given in Table A108.1(1) or Table A108.1(2), pounds per foot (N/m).

v mL = Shear strength of unreinforced masonry, pounds per square inch (kPa). V aa = The shear strength of any URM pier or wall, pounds (N). V ca = Total shear capacity of crosswalls in the direction of analysis immediately above the diaphragm level being investigated, v c L c , pounds (N).

V cb = Total shear capacity of crosswalls in the direction of analysis immediately below the diaphragm level being investigated, v c L c, pounds (N). V p = Shear force assigned to a pier on the basis of its relative shear rigidity, pounds (N). V r = Pier rocking shear capacity of any URM wall or wall pier, pounds (N). v test = Load at incipient cracking for each in-place shear test performed in accordance with Section A106.2.3.6, pounds (N). v tl = Lower bound mortar shear strength, pounds per square inch (kPa). v to = Mortar shear test values as specified in Section A106.2.3.6, pounds per square inch (kPa). v u = Unit shear capacity value for a diaphragm sheathed with any of the materials given in Table A108.1(1) or A108.1(2), pounds per foot (N/m).

V wx = Total shear force resisted by a shear wall at the level under consideration, pounds (N). W = Total seismic dead load as defined in the building code, pounds (N). W d = Total dead load tributary to a diaphragm level, pounds (N). W w = Total dead load of a URM wall above the level under consideration or above an open-front building, pounds (N). W wx = Dead load of a URM wall assigned to level x halfway above and below the level under consideration, pounds (N). Σ v u D = Sum of diaphragm shear capacities of both ends of the diaphragm, pounds (N). ΣΣ v u D = For diaphragms coupled with crosswalls, v u D includes the sum of shear capacities of both ends of diaphragms coupled at and above the level under consideration, pounds (N).

Σ W d = Total dead load of all the diaphragms at and above the level under consideration, pounds (N).

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

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▸ Contents — 2025 California Existing Building Code (Title 24, Part 10)
2025 California Existing Building Code (Title 24, Part 10)
  1. 104.11 for consideration of alternative means of compliance.
  2. Chapter 1 — ADMINISTRATION
  3. Chapter 2 — DEFINITIONS
  4. Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS
  5. Chapter 3A — PROVISIONS FOR ALL COMPLIANCE METHODS
  6. Chapter 4 — REPAIRS
  7. Chapter 4A — REPAIRS
  8. Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD
  9. Chapter 5A — PRESCRIPTIVE COMPLIANCE METHOD
  10. Chapter 6 — CLASSIFICATION OF WORK
  11. Chapter 7 — ALTERATIONS—LEVEL 1
  12. Chapter 8 — ALTERATIONS—LEVEL 2
  13. Chapter 9 — ALTERATIONS—LEVEL 3
  14. Chapter 10 — CHANGE OF OCCUPANCY
  15. Chapter 11 — ADDITIONS
  16. Chapter 12 — HISTORIC BUILDINGS
  17. Chapter 13 — PERFORMANCE COMPLIANCE METHODS
  18. Chapter 14 — RELOCATED OR MOVED BUILDINGS
  19. Chapter 15 — CONSTRUCTION SAFEGUARDS
  20. Chapter 16 — REFERENCED STANDARDS
  21. ▸ Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING B…
    Overview
    1. Section A100 — APPLICATION
    2. Section A101 — PURPOSE
    3. Section A102 — SCOPE
    4. Section A103 — DEFINITIONS
    5. Section A104 — SYMBOLS AND NOTATIONS
    6. Section A105 — GENERAL REQUIREMENTS
    7. Section A106 — MATERIALS REQUIREMENTS
    8. Section A107 — QUALITY CONTROL
    9. Section A108 — DESIGN STRENGTHS
    10. Section A109 — ANALYSIS AND DESIGN PROCEDURE
    11. Section A110 — GENERAL PROCEDURE
    12. Section A111 — SPECIAL PROCEDURE
    13. Section A112 — ANALYSIS AND DESIGN
    14. Section A113 — DETAILED BUILDING SYSTEM DESIGN REQUIREMENTS
    15. Section A114 — WALLS OF UNBURNED CLAY, ADOBE OR STONE MASONRY
    16. Section A201 — PURPOSE
    17. Section A202 — SCOPE
    18. Section A203 — DEFINITIONS
    19. Section A204 — SYMBOLS AND NOTATIONS
    20. Section A205 — GENERAL REQUIREMENTS
    21. Section A206 — ANALYSIS AND DESIGN
    22. Section A207 — MATERIALS OF CONSTRUCTION
    23. Section A301 — GENERAL
    24. Section A302 — DEFINITIONS
    25. Section A303 — STRUCTURAL WEAKNESSES
    26. Section A304 — STRENGTHENING REQUIREMENTS
    27. Section A401 — GENERAL
    28. Section A402 — DEFINITIONS
    29. Section A403 — ANALYSIS AND DESIGN
    30. Section A404 — PRESCRIPTIVE MEASURES FOR WEAK STORY
    31. Section A405 — MATERIALS OF CONSTRUCTION
    32. Section A406 — CONSTRUCTION DOCUMENTS
    33. Section A407 — QUALITY CONTROL
    34. Section A501 — REFERENCED STANDARDS
  22. Appendix B — SUPPLEMENTARY ACCESSIBILITY REQUIREMENTS FOR EXIS…
  23. Appendix C — GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUIL…
  24. Appendix D — BOARD OF APPEALS
  25. Appendix E — TEMPORARY EMERGENCY USES
  26. Appendix A — GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS A…

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