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Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

Section A112 — ANALYSIS AND DESIGN

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] A112.1 General. The following requirements are applicable to both the general procedure and the special procedure for analyzing vertical elements of the lateral force-resisting system.

[BS] A112.2 In-plane shear of unreinforced masonry walls.

[BS] A112.2.1 Flexural rigidity. Flexural components of deflection need not be considered in determining the rigidity of an unreinforced masonry wall.

[BS] A112.2.2 Shear walls with openings. Wall piers shall be analyzed according to the following procedure, which is diagrammed in Figure A112.2.2.

  1. For any pier: 1.1. The pier shear capacity shall be calculated as:

Equation A1-18 v a = v m A n

where:

A n = area of net mortared or grouted section of a wall or wall pier. 1.2. The pier rocking shear capacity shall be calculated as:

Equation A1-19 V r = 0.9 P D D / H 2. The wall piers at any level are acceptable if they comply with one of the following modes of behavior: 2.1. Rocking controlled mode. Where the pier rocking shear capacity is less than the pier shear capacity, in other words, V r < v a, for each pier in a level, forces in the wall at that level, V wx, shall be distributed to each pier in proportion to P D D/H .

For the wall at that level:

Equation A1-20 0.7 V wx < SV r 2.2. Shear controlled mode. Where the pier shear capacity is less than the pier rocking capacity, in other words, v a < V r in one or more pier(s) in a level, forces in the wall at the level, V wx, shall be distributed to each pier in proportion to D/H .

For each pier at that level: Equation A1-21 V p < v a

and

Equation A1-22 V p < V r If V p < v a for each pier and V p - V r for one or more piers, such piers shall be omitted from the analysis, and the procedure shall be repeated for the remaining piers, unless the wall is strengthened and reanalyzed. 3. Masonry pier tension stress. Unreinforced masonry wall piers need not be analyzed for tension stress.

APPENDIX A-14 2025 CALIFORNIA EXISTING BUILDING CODE

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

APPENDIX A—GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

[BS] FIGURE A112.2.2—ANALYSIS OF URM WALL IN-PLANE SHEAR FORCES

PIER IS OVERSTRESSED IN SHEAR

V a = Allowable shear strength of a pier.

V p = Shear force assigned to a pier on the basis of a relative shear rigidity analysis.

RETURN

V r

V WX

∑ V r

= Rocking shear capacity of pier.

= Total shear force resisted by the wall.

= Rocking shear capacity of all piers in the wall.

[BS] A112.2.3 Shear walls without openings. Shear walls without openings shall be analyzed the same as for walls with openings, except that V r shall be calculated as follows: Equation A1-23 V r = 0.9( P D + 0.5 P w ) D / H

[BS] A112.3 Plywood-sheathed shear walls. Plywood-sheathed shear walls may be used to resist lateral forces for URM buildings with flexible diaphragms analyzed according to provisions of Section A111. Plywood-sheathed shear walls shall not be used to share lateral forces with other materials along the same line of resistance.

[BS] A112.4 Combinations of vertical elements.

[BS] A112.4.1 Seismic force distribution. Seismic forces shall be distributed among the vertical-resisting elements in proportion to their relative rigidities, except that moment-resisting frames shall comply with Section A112.4.2.

[BS] A112.4.2 Moment-resisting frames. Moment resisting frames shall not be used with an unreinforced masonry wall in a single line of resistance unless the wall has piers that have adequate shear capacity to sustain rocking in accordance with Section A112.2.2. The frames shall be designed in accordance with the building code to resist 100 percent of the seismic forces tributary to that line of resistance, as determined from Section A111.2. The story drift ratio shall be limited to 0.0075.

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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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