Development of preliminary load and resistance factor design of drilled shafts in Iowa.

Details

• Creators:
  Ng, Kam W. ; Sritharan, Sri ; Ashlock, Jeramy C.
• Corporate Creators:
  Iowa State University. Bridge Engineering Center
• Corporate Contributors:
  Iowa. Dept. of Transportation ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Load factor
  • Databases
  • Bridge design
  • Resistance (Mechanics)
  • End bearing piles
  • Case studies
  • Bridge foundations
• Publication/ Report Number:
  InTrans Project 11-410
• Resource Type:
  Tech Report
• Geographical Coverage:
  Iowa
• Corporate Publisher:
  Iowa State University. Institute for Transportation
• Abstract:
  The Federal Highway Administration (FHWA) mandated utilizing the Load and Resistance Factor Design (LRFD) approach for all new ; bridges initiated in the United States after October 1, 2007. To achieve part of this goal, a database for Drilled SHAft Foundation ; Testing (DSHAFT) was developed and reported on by Garder, Ng, Sritharan, and Roling in 2012. DSHAFT is aimed at assimilating ; high-quality drilled shaft test data from Iowa and the surrounding regions. DSHAFT is currently housed on a project website ; (http://srg.cce.iastate.edu/dshaft) and contains data for 41 drilled shaft tests. ; The objective of this research was to utilize the DSHAFT database and develop a regional LRFD procedure for drilled shafts in Iowa ; with preliminary resistance factors using a probability-based reliability theory. This was done by examining current design and ; construction practices used by the Iowa Department of Transportation (DOT) as well as recommendations given in the American ; Association of State Highway and Transportation Officials (AASHTO) LRFD Bridge Design Specifications and the FHWA drilled shaft ; guidelines. ; Various analytical methods were used to estimate side resistance and end bearing of drilled shafts in clay, sand, intermediate ; geomaterial (IGM), and rock. Since most of the load test results obtained from O-cell do not pass the 1-in. top displacement criterion ; used by the Iowa DOT and the 5% of shaft diameter for top displacement criterion recommended by AASHTO, three improved ; procedures are proposed to generate and extend equivalent top load-displacement curves that enable the quantification of measured ; resistances corresponding to the displacement criteria. ; Using the estimated and measured resistances, regional resistance factors were calibrated following the AASHTO LRFD framework and ; adjusted to resolve any anomalies observed among the factors. To illustrate the potential and successful use of drilled shafts in Iowa, the ; design procedures of drilled shaft foundations were demonstrated and the advantages of drilled shafts over driven piles were addressed ; in two case studies
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28539/dot_28539_DS1.pdf
• File Type:
  [PDF - 4.96 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:074388113f29cc8c0f6657f93d5799cb07bb9f8cd1c61b2c49c11b0606ea55bc4ae5904cb822fb1a8a976141d68fa7fa4679550032424a77519ff39a34bc119b