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Chapter 18 — SOILS AND FOUNDATIONS

Section 1811

California Building Code (Title 24, Part 2) · 2022 edition · updated 2026-09-12 · California

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

PRESTRESSED ROCK AND SOIL FOUNDATION

ANCHORS [OSHPD 1R, 2B & 5]

1811.1 General.

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

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. 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 perma- nent and extended temporary anchors in service more than 2 years. A minimum of Class II corrosion protec- tion 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

SOILS AND FOUNDATIONS

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 require- ments.

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 combina- tions in Section 2.4 of ASCE 7 and shall not exceed 60 percent of the specified 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 compat- ibility or building drift where it may be significant.

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▸Contents — California Building Code (Title 24, Part 2)
California Building Code (Title 24, Part 2)
  1. Chapter 2 — DEFINITIONS AND ABBREVIATIONS
  2. Appendix G — FLOOD-RESISTANT
  3. Appendix L — EARTHQUAKE RECORDING
  4. Appendix M — TSUNAMI-GENERATED
  5. Appendix N — REPLICABLE
  6. Appendix O — PERFORMANCE-BASED
  7. Chapter 1 — SCOPE AND ADMINISTRATION
  8. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  9. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
  10. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  11. Chapter 6 — TYPES OF CONSTRUCTION
  12. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  13. Chapter 7A — MATERIALS AND CONSTRUCTION
  14. Chapter 8 — INTERIOR FINISHES
  15. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  16. Chapter 10 — MEANS OF EGRESS
  17. Chapter 11A — HOUSING ACCESSIBILITY
  18. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  19. Chapter 12 — INTERIOR ENVIRONMENT
  20. Chapter 14 — EXTERIOR WALLS
  21. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  22. Chapter 16 — STRUCTURAL DESIGN
  23. Chapter 16A — STRUCTURAL DESIGN
  24. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  25. ▸Chapter 18 — SOILS AND FOUNDATIONS
    Overview
    1. Section 1801
    2. Section 1802
    3. Section 1803
    4. Section 1804
    5. Section 1805
    6. Section 1806
    7. Section 1807
    8. Section 1808
    9. Section 1809
    10. Section 1810
    11. Section 1811
    12. Section 1812
    13. Section 1813
    14. Section 1801A
    15. Section 1802A
    16. Section 1803A
    17. Section 1804A
    18. Section 1805A
    19. Section 1806A
    20. Section 1807A
    21. Section 1808A
    22. Section 1809A
    23. Section 1810A
    24. Section 1811A
    25. Section 1812A
    26. Section 1813A
  26. Chapter 19 — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. Chapter 22 — STEEL
  30. Chapter 23 — WOOD
  31. Chapter 24 — GLASS AND GLAZING
  32. Chapter 25 — GYPSUM BOARD, GYPSUM PANEL PRODUCTS AND PLASTER
  33. Chapter 26 — PLASTIC
  34. Chapter 27 — ELECTRICAL
  35. Chapter 28 — MECHANICAL SYSTEMS
  36. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  37. Chapter 31 — SPECIAL CONSTRUCTION
  38. Chapter 31B — PUBLIC POOLS
  39. Chapter 31C — RADIATION
  40. Chapter 31D — FOOD ESTABLISHMENTS
  41. Chapter 31F — MARINE OIL TERMINALS
  42. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  43. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  44. Chapter 35 — REFERENCED STANDARDS
  45. Appendix A — EMPLOYEE QUALIFICATIONS
  46. Appendix B — BOARD OF APPEALS
  47. Appendix C — GROUP U – AGRICULTURAL BUILDINGS
  48. Appendix D — FIRE DISTRICTS
  49. Appendix F — RODENTPROOFING
  50. Appendix H — SIGNS
  51. Appendix I — PATIO COVERS
  52. Appendix J — GRADING
  53. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES
  54. Appendix P — EMERGENCY HOUSING

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