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

2263. RR for setup is a ratio of measured pile setup resistance and estimated pilesetup resistance as listed in Table 6.4. The measured pile setup resistance isthe difference between SLT measured pile resistance at any time (t) and thepile resistance at the EOD condition estimated, using either WEAP orCAPWAP. The estimated pile setup resistance was determined using theproposed SPT-based setup equation.Because the CDF plots shown in Figure 6.1, 6.2, 6.3, and 6.4 were lognormallydistributed, the mean and standard deviation were represented with ―Loc‖ and ―Scale‖,respectively. To implement Eqs. (6.4) and (6.6), the normally distributed resistance bias (λ R )was back-calculated using Eq. (6.8), and the normally distributed coefficient of variation(COV R ) was back-calculated using Eq. (6.9).[ ( )] (6.8)√( ) (6.9)Using these probabilistic characteristics of resistances (λ R and COV R ), the regionalresistance factors were calculated and are given in Table 6.6 and Table 6.7 for WEAP andCAPWAP, respectively. Table 6.6 shows that the resistance factors for the same soil profileand resistance condition (EOD, BOR, or setup) are similar, which concludes the insensitivityof different soil input procedures and the validity of the 70%-rule used in classifying the soilprofile. However, the soil input procedure with the highest resistance factor does notnecessarily provide the most efficient and economic pile design, since different proceduresprovide different nominal pile resistance estimations. For instance, in the clay profile and atthe EOD condition, the DRIVEN procedure has the highest φ value of 0.66 when comparedwith 0.65 for the Iowa Blue Book method. Using the estimated nominal pile resistances ofISU6 (601 kN for DRIVEN and 624 kN for the Iowa Blue Book) as listed in Table 6.2, thefactored pile resistance (φR EOD ) for DRIVEN becomes 397 kN, which is smaller than 405 kN