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

1303.4.7. Static load testsFollowing completion of all restrikes, vertical SLTs were performed on test pilesfollowing the ―Quick Test‖ procedure of ASTM D 1143 according to the schedule indicatedin Table 3.3. In addition to recording the strain data along the pile shaft, four 250 mm (0.8ft)-stroke displacement transducers installed at the four extreme edges of the test pile flangesrecorded the pile vertical movement during each loading and unloading step. For each pile,the pile resistance (or the total nominal resistance) was calculated using the measured loaddisplacementcurve and the Davisson’s criterion (Davisson, 1972), whereas the variation inpile force along the depth was estimated using the measured strain data at every load step asshown in Figure 3.9. By extending the slope of the pile force resistance along the pile lengthover the bottom two pairs of strain data, the end bearing contribution was also estimated atthe toe of each pile. The nominal pile resistance of ISU 5 was found to be 1081 kN (243kip), and its distribution along the pile length is shown in Figure 3.9 (by the solid linewithout markers) as established from interpolation of the force distribution curvescorresponding to 1051 kN (236 kip) and 1114 kN (250 kip). In this case, the end bearingcomponent was 247 kN (56 kip) or 23% of the total pile resistance of 1081 kN.Subtracting the end bearing resistance from the total nominal pile resistance, the shaftresistance for ISU5 was determined to be 834 kN (188 kip). Table 3.3 lists the shaftresistance and end bearing for all test piles except ISU4 and ISU6, for which large number ofstrain gauges failed during the test and thus this information could not be extracted withsufficient accuracy.3.5. Results3.5.1. Observed pile setupIn addition to the increase in hammer blow counts observed Figure 3.7 between theEOD condition and BOR6 for ISU5, Table 3.4 summarizes the percent of pile resistanceincrease at different times (∆R t ) with reference to the calculated pile resistance at EOD