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

70summarized in Table 2.11, Table 2.12, and Table 2.13 for PDA, CAPWAP, and WEAPrespectively. The piles tested included timber piles, screwed piles, steel H-piles, closed andopen ended steel pipe piles, precast concrete square piles, drilled shafts, prestressed concretecylinder spun piles, monotube piles, and composite steel, and concrete piles. The number oftest database (N) used in the analyses varied from one (1) to as large as two hundred and six(206). The average mean ratio values of PDA, CAPWAP, and the WEAP are 1.118, 0.979,and 1.008 respectively. The results depict that dynamic analysis methods using PDA andWEAP tend to over-predict the pile resistance and CAPWAP tends to give conservativeresults. By comparing the mean values, WEAP provides the best dynamic method inestimating pile resistance with the closest mean ratio to one; PDA gives the relative lessaccurate results, and CAPWAP in between. In fact, many of the WEAP analyses wererefined using CAPWAP soil parameters determined at BOR, and this could be the reason forgenerating good estimations from WEAP. Among the three methods, CAPWAP is the mostpopular dynamic analysis method in estimating the pile resistance and many studies werepublished to compare CAPWAP results with static load tests. Table 2.11 shows that theratios for PDA method vary from 0.734 to 2.132. In addition, the ratios for CAPWAP asshown in Table 2.12 vary from 0.725 to 1.457. As for WEAP shown in Table 2.13, the ratiosvary from 0.873 to 1.295. This study illustrates that PDA has a larger scatter prediction thanCAPWAP and WEAP.The average COV of all cases used in the PDA, CAPWAP, and the WEAP analysesare 0.200, 0.166, and 0.166 respectively. Generally, the average pile resistance estimationwithin each case is relatively more scatter for PDA than CAPWAP and WEAP. The range ofCOV for CAPWAP and WEAP are between 0.014 to 0.411 and 0.065 to 0.350, respectively,whereas the range for PDA is from 0.059 to 0.329. Furthermore, the COV for the PDAmethod increases from cases with single material piles such steel or concrete piles tocomposite piles as noticed by comparing Cases 4 and 11 with Cases 6 and 9. Similarobservations are noticed in the CAPWAP and WEAP.The relationship between soil profile and the mean ratios of the dynamic analysis