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Chapter 18 — SOILS AND FOUNDATIONS

Section 1811 — PRESTRESSED ROCK AND SOIL FOUNDATION ANCHORS [OSHPD 1R, 2 & 5]

2025 California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-07-29 · California

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

1811.1 General.

The requirements of this section address the use of vertical rock and soil anchors in resisting seismic or wind overturn- ing forces, resulting in tension on shallow foundations.

1811.2 Adoption.

Except for the modifications as set forth in Sections 1811.3 and 1811.4, all prestressed rock and soil foundation anchors shall comply with PTI Recommendations for Prestressed Rock and Soil Anchors.

1811.3 Geotechnical requirements .

The geotechnical report for the Prestressed Rock & Soil Foundation Anchors shall address the_ following: 1. Minimum diameter and minimum spacing for the anchors including consideration of group effects. 2. Maximum unbonded length and minimum bonded length of the tendon.

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

SOILS AND FOUNDATIONS

3. Maximum recommended anchor tension capacity based upon the soil or rock strength/grout bond and anchor depth/spacing. 4. Allowable bond stress at the ground/grout interface and applicable factor of safety for ultimate bond stress. 5. Anchor axial tension stiffness recommendations at the anticipated anchor axial tension displacements, when required for structural analysis. 6. Minimum grout pressure for installation and post-grout pressure. 7. Class I corrosion protection is required for all permanent and extended temporary anchors in service more than 2 years. A mini- mum of Class II corrosion protection is required for temporary anchors in service less than or equal to 2 years. 8. Performance test shall be at a minimum of 1.6 times the design loads, but shall not exceed 80 percent of the specified minimum tensile strength of the tendons. There shall be a minimum of two preproduction test anchors. Preproduction test anchors shall be tested to ultimate load or a maximum of 0.80 times the specified minimum tensile strength of the tendon. A creep test is required for all prestressed anchors with greater than 10 kips of lock-off prestressing load. 9. Lock-off prestressing load requirements. 10. Acceptable drilling methods. 11. Geotechnical observation and monitoring requirements.

1811.4 Structural Requirements .

1. Tendons shall be thread-bar anchors conforming to ASTM A722. 2. The anchors shall be placed vertical. 3. Design loads shall be based upon the load combinations in Section 2.4 of ASCE 7 and shall not exceed 60 percent of the speci- fied minimum tensile strength of the tendons. 4. Ultimate load shall be based upon the lesser of the strength of the superstructure elements, the maximum forces from a fully yielded structural system and forces from the load combinations with overstrength factor in accordance with ASCE 7, Section 12.4.3 and shall not exceed 80 percent of the specified minimum tensile strength of the tendons. 5. The anchor shall be designed to fail in grout bond to the soil or rock before pullout of the soil wedge by group effect. 6. Foundation design shall incorporate the effect of lock-off loads. 7. Design shall account for as-built locations of soil anchors considering all the acceptable construction tolerances. 8. Design shall account for both short- and long-term deformation. 9. Enforcement agency may require consideration of anchor deformation in evaluating deformation compatibility or building drift where it may be significant.

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▸ Contents — 2025 California Building Code (Title 24, Part 2)
2025 California Building Code (Title 24, Part 2)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  4. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
  5. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  6. Chapter 6 — TYPES OF CONSTRUCTION
  7. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  8. Chapter 7A — MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR W…
  9. Chapter 8 — INTERIOR FINISHES
  10. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  11. Chapter 10 — MEANS OF EGRESS
  12. Chapter 11 — RESERVED
  13. Chapter 11A — HOUSING ACCESSIBILITY
  14. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  15. Chapter 12 — INTERIOR ENVIRONMENT
  16. Chapter 13 — ENERGY EFFICIENCY
  17. Chapter 14 — EXTERIOR WALLS
  18. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  19. Chapter 16 — STRUCTURAL DESIGN
  20. Chapter 16A — STRUCTURAL DESIGN
  21. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  22. Chapter 17A — SPECIAL INSPECTIONS AND TESTS
  23. ▸ Chapter 18 — SOILS AND FOUNDATIONS
    Overview
    1. Section 1801 — GENERAL
    2. Section 1802 — DESIGN BASIS
    3. Section 1803 — GEOTECHNICAL INVESTIGATIONS
    4. Section 1804 — EXCAVATION, GRADING AND FILL
    5. Section 1805 — DAMPPROOFING AND WATERPROOFING
    6. Section 1806 — PRESUMPTIVE LOAD-BEARING VALUES OF SOILS
    7. Section 1807 — FOUNDATION WALLS, RETAINING WALLS AND EMBEDDED …
    8. Section 1808 — FOUNDATIONS
    9. Section 1809 — SHALLOW FOUNDATIONS
    10. Section 1810 — DEEP FOUNDATIONS
    11. Section 1811 — PRESTRESSED ROCK AND SOIL FOUNDATION ANCHORS [O…
    12. Section 1812 — EARTH RETAINING SHORING [OSHPD 1R, 2 & 5]
    13. Section 1813 — VIBRO STONE COLUMNS FOR GROUND IMPROVEMENT [OSH…
  24. Chapter 18A — SOILS AND FOUNDATIONS
  25. Chapter 19 — CONCRETE
  26. Chapter 19A — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. Chapter 21A — MASONRY
  30. Chapter 22 — STEEL
  31. Chapter 22A — STEEL
  32. Chapter 23 — WOOD
  33. Chapter 24 — GLASS AND GLAZING
  34. Chapter 25 — GYPSUM PANEL PRODUCTS AND PLASTER
  35. Chapter 26 — PLASTIC
  36. Chapter 27 — ELECTRICAL
  37. Chapter 28 — MECHANICAL SYSTEMS
  38. Chapter 29 — PLUMBING SYSTEMS
  39. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  40. Chapter 31 — SPECIAL CONSTRUCTION
  41. Chapter 31A — SYSTEMS FOR WINDOW CLEANING OR EXTERIOR BUILDING…
  42. Chapter 31B — PUBLIC POOLS
  43. Chapter 31C — RADIATION
  44. Chapter 31D — FOOD ESTABLISHMENTS
  45. Chapter 31F — MARINE OIL TERMINALS
  46. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  47. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  48. Chapter 34 — RESERVED
  49. Chapter 35 — REFERENCED STANDARDS
  50. Appendix A — EMPLOYEE QUALIFICATIONS
  51. Appendix B — BOARD OF APPEALS
  52. Appendix C — GROUP U—AGRICULTURAL BUILDINGS
  53. Appendix D — FIRE DISTRICTS
  54. Appendix E — RESERVED
  55. Appendix F — RODENTPROOFING
  56. Appendix G — FLOOD-RESISTANT CONSTRUCTION
  57. Appendix H — SIGNS
  58. Appendix I — PATIO COVERS
  59. Appendix J — GRADING
  60. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES PROTECTED B…
  61. Appendix L — EARTHQUAKE RECORDING INSTRUMENTATION
  62. Appendix M — TSUNAMI-GENERATED FLOOD HAZARDS
  63. Appendix N — REPLICABLE BUILDINGS
  64. Appendix O — PERFORMANCE-BASED APPLICATION
  65. Appendix P — SLEEPING LOFTS
  66. Appendix Q — EMERGENCY HOUSING

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