LONG TERM OVERTURNING LOADS ON DRILLED SHAFT FOOTINGS

ONE PART OF A THREE-YEAR STUDY IS SUMMARIZED TO DEVELOP A USABLE DESIGN PROCEDURE FOR DRILLED SHAFT FOOTINGS SUBJECTED TO ALL TYPES OF OVERTURNING LOADS. THE PURPOSE OF THE FIELD AND LABORATORY LONG-TERM LOADING TESTS WAS TO DETERMINE WHAT VALUES OF LONG-TERM LATERAL LOADS COULD BE SAFELY APPLIED TO DRILLED SHAFT FOOTINGS WITHOUT UNDUE ROTATION, AND ALSO TO DEVELOP A LABORATORY CREEP TEST WHICH WOULD AID IN THESE PREDICTIONS. BASED ON THE LIMITED NUMBER OF LABORATORY CREEP TESTS WHICH WERE PERFORMED, IT DOES NOT APPEAR THAT THESE TESTS CAN BE USED UNTIL ADDITIONAL INFORMATION IS OBTAINED ON SEVERAL SOIL TYPES. UNTIL THIS INFORMATION BECOMES AVAILABLE, IT IS SUGGESTED THAT THE FOLLOWING PERCENTAGES OF THE CALCULATED 5 DEGREE OVERTURNING LOAD BE USED FOR ADMISSIBLE LONG-TERM CREEP LOADS: SOFT CLAYS, 33 TO 50%; STIFF, NON-FISSURED CLAYS, 50%; SANDS, 50 TO 75%; AND STIFF, FISSURED CLAYS, 33%. ALTHOUGH THE USE OF THESE PERCENTAGES FOR ALLOWABLE LONG-TERM LOADS SHOULD RESULT IN A TERMINATING ROTATION, THIS ROTATION WILL PROBABLY BE SIGNIFICANT (ON THE ORDER OF ONE DEGREE). THE JUDGMENT OF THE ENGINEER IS NECESSARY TO DECIDE WHAT ROTATION IS ACCEPTABLE FOR A PARTICULAR FOOTING. IF THE ACCEPTABLE ROTATION IS SEVERELY LIMITED BY FUNCTIONAL OR AESTHETIC CONSIDERATIONS, THE USE OF SIGNIFICANTLY SMALLER PERCENTAGES OF THE 5 DEGREE LOAD MAY BE NECESSARY. /BPR/

• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas State Department of Highways & Public Transp

  11th and Brazos Streets
  Austin, TX  United States  78701

  Bureau of Public Roads /US

  400 7th Street, SW
  Washington, DC  United States  20590
• Authors:
  • Dunlap, W A
  • Ivey, D L
  • SMITH, H L
• Publication Date: 0

Subject/Index Terms

• TRT Terms: Creep; Drilling; Footings; Loads; Overturning; Properties of materials; Shafts (Machinery); Soils
• Uncontrolled Terms: Lateral loads; Soil properties
• Subject Areas: Bridges and other structures; Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00207951
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS, STATEDOT
• Created Date: Jul 27 1970 12:00AM