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

58the spring stiffness develops only when it has extended beyond the slack distance (d sl ), andthe spring force is always zero within the slack distance. Normally, a splice model isrequired when some forceless deformation is desired such as the mechanical splices ofconcrete piles.CompressiveForceNominal Stiffness, kF limk/c a2CompressiveDeformationk/c a2d scd sld sckFigure 2.13: Force deformation curve for slack model (after Pile Dynamic Inc., 2005)2.5.6. Soil modelWEAP used the Smith’s approach to model the surrounding soil with springs anddashpots as shown in Figure 2.12. Quake and the damping factor are the two soil parametersthat describe the soil model, and their estimates have been recommended by Hannigan et al.(1998) as listed in Table 2.5 for WEAP analysis.Five soil damping models are available in WEAP. The standard Smith and Smithviscous damping models are the most common in practices. The remaining models are theCase non-dimensionalized viscous damping, Coyle and Gibson damping, and Rauschedamping, and they are mainly used for research applications. The standard Smith damping