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:
  Bridge Design Bridge Foundations Case Studies Databases End Bearing Piles Load Factor Resistance (Mechanics)
• 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
  
  
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:074388113f29cc8c0f6657f93d5799cb07bb9f8cd1c61b2c49c11b0606ea55bc4ae5904cb822fb1a8a976141d68fa7fa4679550032424a77519ff39a34bc119b
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/28539/dot_28539_DS1.pdf
• File Type:
  [PDF - 4.96 MB ]