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

208respectively. Figure 5.5 illustrates that the φ setup values reduce gradually with increasingQ D /Q L ratios from 0.52 to about 2.12, and the φ setup values reduce at a slower rate thereafter.Figure 5.5(a) indicates that the increase in Q D /Q L ratio by a factor of 6.8 from 0.52 to 3.53only reduces the φ setup values by a small factor of about 1.2. Hence, it can be generallyconcluded that the φ setup values are not sensitive to the Q D /Q L ratios. However, the sensitivityincreases at a larger α value of 1.5 as shown in Figure 5.5(b), indicated by the faster decreasein the φ setup values. In order to optimize the pile setup contribution by selecting an α value of1.0 during pile designs, φ setup values of 0.32 and 0.26 can be conservatively recommended forβ T values of 2.33 and 3.00, respectively.0.450.40Note: Based on φ EOD = 0.78and 0.65 for β T = 2.33 and3.00, respectively0.450.40Note: Based on φ EOD = 0.78 and 0.65for β T = 2.33 and 3.00, respectivelyResistance Factor for Setup, φ setup0.350.300.250.200.150.100.050.00β T = 2.33β T = 3.00(a)0 1 2 3 4Resistance Factor for Setup, φ setup0.350.300.250.200.150.100.050.00β T = 2.33β T = 3.00(b)0 1 2 3 4Ratio of Dead to Live Load, Q D /Q LRatio of Dead to Live Load, Q D /Q LFigure 5.5: Relationship between resistance factor for setup and dead to live load ratio for (a)α value = 1.0; and (b) α value = 1.55.7. DependabilityAlthough separate resistance factors have been developed to account for thedifference in uncertainties, it is important to demonstrate the dependability of the proposed