curvature at increasing loads. The curves calculated using this method were called

displacement in this chapter.

 The experimental curvature was also determined based on a numerical differential

method. With the numerical differential method the curvature is calculated based on

displacement values for adjacent points in contrast to the curvature based on the

displacement profile which the curvature is calculated based on a fitted line through all

displacement points that can neutralized localized effects. More details on the numerical

differential method can be found in chapter 5.

 The experimentally calculated M-0 curves from both methods (displacement

profile and numerical differential) for specimen SCC3 and SCG3 are presented in Figs 6-

44 and 6-45.

 140
 120
 100
 80
 60
 40
 -B-Disp. (SCC3)
 0
 20 /-A-Diff. (SCC3)

 0 0.0005 0.001 0.0015 0.002 0.0025
 Curvature (rads/in)

Figure 6-44. Experimental M-D curves for piles SCC3

 Typically the differential moment curvature curves were different than the

displacement moment curvature curves as is noted from Figs 6-44 and 6-45. The obvious

difference was the slope of the curve. The differential curves had larger slopes than the

displacement curves. For a given load the curvature calculated based on the differential