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

207conditions and design practices, Figure 5.4 shows the variation of φ setup values based on aconstant Q D /Q L ratio of 2. Figure 5.4 shows that larger φ setup values will be recommended iflarger φ EOD values are calibrated for α values ranging between 0.2 and 1.2. The φ setup valuesbecome less sensitive to φ EOD values at α value of 1.4. However, if a local design methodyields conservative pile designs (i.e., α values larger than 1.5) and results in a φ EOD valuegreater than 0.75, pile setup resistance becomes dispensable for satisfying the total factoredload.Resistance Factor for Setup, φ setup0.600.500.400.300.200.10α = 0.2α = 0.4α = 0.6α = 0.8α = 1.0α = 1.2α = 1.4α = 1.5α = 1.6Note: Based on constant Q D /Q L = 2.00.000.60 0.65 0.70 0.75 0.80 0.85 0.90Resistance Factor for EOD, φ EODFigure 5.4: Relationship between resistance factors for setup and for EODThe aforementioned observations shown in Figure 5.2, 5.3 and 5.4 are based on afixed Q D /Q L of 2, and it is of interest to investigate the influence of this ratio, which is afunction of the span length of a bridge, on the φ setup values. Based on the AASHTO (2003)Specifications, the following dead to live load ratios 0.52, 1.06, 1.58, 2.12, 2.64, 3.00, and3.53 are suggested for span lengths of 9, 18, 27, 36, 45, 50, and 60 m. For an illustrationpurpose, α values of 1.0 and 1.5 were selected as shown in Figure 5.5(a) and (b),