S - Kam Ng PhD Dissertation Final.pdf - Digital Repository of CCEE ...

293improved. The regionally-calibrated resistance factors are summarized as below:1. For the WEAP approach considering the EOD condition, the regionally-calibratedresistance factors were 0.55, 0.65, and 0.83 for the sand, clay, and mixed soilprofile, respectively, which were higher than the AASHTO’s recommended valueof 0.50.2. For the CAPWAP approach considering the BOR condition, the regionallycalibratedresistance factors were 0.77, 0.80, and 0.93 for the sand, clay, andmixed soil profile, respectively, which were all higher than the ASSHTO’srecommended value of 0.75.Using the procedure developed in Chapter 5, the effect of pile setup in a clay profilewas incorporated as part of the LRFD recommendations to elevate the efficiency of bridgefoundations, so the economic advantages of pile setup can be attained. Due to a higheruncertainty involved in estimating the pile setup resistance (higher COV R ) and the selectionof a conservative α value of 1.60, smaller φ setup values (0.21 for WEAP-Iowa Blue Book,0.26 for WEAP-Iowa DOT, and 0.37 for CAPWAP based on β T =2.33) were determined8.2.4. Construction controlTo minimize the discrepancy between design and field pile resistances and toassimilate the construction control capability of dynamic analysis methods during the designstage, a construction control procedure was established in Chapter 6 using a probabilisticapproach. This was achieved by integrating WEAP and CAPWAP as construction controlmethods as part of the design process. Construction control was accounted for bydetermining a construction control factor corresponding to the 50% cumulative densityfunction of the resistance ratio of the construction control method and the Iowa Blue Bookmethod. These construction control factors were calculated according to the selection ofconstruction control method (WEAP or CAPWAP) during pile driving and the presence ofsoil type surrounding the pile. A minimum construction control factor of 1.0 was suggestedto maintain the economic advantages and the original efficiency of the Iowa Blue Bookmethod. The corrected resistance factor, after considering construction control, was limited