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

194C h = horizontal coefficient of consolidation determined from CPT pore waterpressure dissipation tests and strain path method, cm 2 /min. or in. 2 /minute,N a = average SPT N-value by weighting to cohesive soil thicknesses,r p = equivalent pile radius based on cross-sectional area, cm 2 or in. 2 ,f r = remolding recovery factor (use 0.149 for the WEAP-SA method),t = time elapsed after EOD, minute, andt EOD = time at the end of driving (assumes a value of 1 minute).Detailed derivation and validation of Eq. (5.1a) can be found in Chapter 4 as well asfor CAse Pile Wave Analysis Program (CAPWAP). However, Eq. (5.1a) for WEAP-SA wasselected throughout the paper based on a database of steel H-piles to illustrate the proposedprocedure of incorporating pile setup in accordance with LRFD. Nevertheless, the proposedprocedure can be generally and practically implemented based on any regional database thatreflects the local soil conditions, pile types, and setup quantification methods.According to Eq. (5.1b), the total nominal pile resistance (R t ) comprises both initialpile resistances at EOD (R EOD ) estimated using WEAP and pile setup resistance (R setup ) fromeither Eq. (5.1a) or any other existing empirical setup methods. Unlike the aforementionedsetup evaluation involving the pile tests, each of the pile resistance components has its ownsource of uncertainties, such as those resulting from the in-situ measurement of soilproperties and the semi-empirical approach adapted for Eq. (5.1a). To incorporate such apile setup estimate in LRFD satisfactorily, it should be realized that the impact of theuncertainties associated with the R EOD and the R setup components are different and they shouldbe accounted simultaneously to reach the same target reliability index. While ensuring thatthe reliability theory based LRFD framework is adequately followed in this process, itenables incorporation of two resistance factors: one for the setup and the other for the pileresistance at the EOD condition. The concept of separately addressing the differentuncertainties associated with R EOD and R setup has been recognized by Komurka et al. (2005),but this procedure was suggested using separate safety factors for both resistances.Furthermore, Yang and Liang (2006) used an intensive computational First Order Reliability